Readiness of the ATLAS Tile Calorimeter for LHC collisions
EEUROPEAN ORGANIZATION FOR NUCLEAR RESEARCH
CERN-PH-EP-2010-02429 July 2010
Readiness of the ATLAS Tile Calorimeter for LHC collisions
The ATLAS Collaboration ∗ Abstract
The Tile hadronic calorimeter of the ATLAS detector has undergone extensive testing in the experi-mental hall since its installation in late 2005. The readout, control and calibration systems have beenfully operational since 2007 and the detector has successfully collected data from the LHC singlebeams in 2008 and first collisions in 2009. This paper gives an overview of the Tile Calorimeterperformance as measured using random triggers, calibration data, data from cosmic ray muons andsingle beam data. The detector operation status, noise characteristics and performance of the calibra-tion systems are presented, as well as the validation of the timing and energy calibration carried outwith minimum ionising cosmic ray muons data. The calibration systems’ precision is well below thedesign value of 1 %. The determination of the global energy scale was performed with an uncertaintyof 4 %. ∗ See Appendix A for the list of collaboration members a r X i v : . [ phy s i c s . i n s - d e t ] N ov eadiness of the ATLAS Tile Calorimeter for LHC collisions 1 The ATLAS Tile Calorimeter (TileCal) [1] is the barrel hadronic calorimeter of the ATLAS experi-ment [2] at the CERN Large Hadron Collider [3]. Calorimeters have a primary role in a general-purposehadron collider detector. The ATLAS calorimeter system provides accurate energy and position measure-ments of electrons, photons, isolated hadrons, taus and jets. It also contributes in particle identificationand in muon momentum reconstruction. In the barrel part of ATLAS, together with the electromag-netic barrel calorimeter, TileCal focuses on precise measurements of hadrons, jets, taus and the missingtransverse energy ( E miss T ). The performance requirements are driven by the ATLAS physics programme:– The energy resolution for jets of σ / E =
50 % / (cid:112) E ( GeV ) ⊕ E miss T is important for many physics signatures, in particular for SUSYparticle searches and new physics. In addition to sufficient total calorimeter thickness and a largecoverage in pseudorapidity, this very sensitive measurement requires also a small fraction of deaddetector regions which create fake E miss T . The requirement depends on the signal to backgroundratio of the search.The Tile Calorimeter has been installed in the experimental hall since 2005 and since then has undergonethrough several phases of commissioning and integration in the ATLAS detector system. The main goalof this paper is to present the outcome of this commissioning phase, at the start of the LHC collisionsdata-taking. The paper is organised as follows: Section 2 gives a brief description of the Tile Calorimeterand discusses the overall detector status and the data-taking conditions after the commissioning wascarried out. Section 3 presents the method for the channel signal reconstruction, the overall quality ofthe detector in coverage, noise characteristics and conditions stability. Section 4 shows the details on thethree calibration systems used to set and maintain the cell energy scale and set the timing offsets, as wellas results on the precision and stability of each system. The related energy scale uncertainties and theinter-calibration issues are also discussed. The last section (Section 5) is devoted to the validation of theperformance using data from cosmic muons produced in cosmic ray showers in the atmosphere, referredto in short form throughout this paper as “cosmic muons” or “cosmic ray muons”. Results are presentedon energy and time reconstruction, uniformity across the calorimeter and comparison with Monte Carlosimulations. A subsection is devoted to the intercalibration of the scintillators that are located in the gapbetween barrel and extended barrels. The ATLAS Collaboration Fig. 1:
A cut-away drawing of the ATLAS inner detector and calorimeters. The Tile Calorimeter consists ofone barrel and two extended barrel sections and surrounds the Liquid Argon barrel electromagnetic and endcaphadronic calorimeters. In the innermost radii of ATLAS, the inner detector (shown in grey) is used for precisiontracking of charged particles.
500 1000 1500 mm0 A3 A4 A5 A6 A7 A8 A9 A10A1 A2BC1 BC2 BC3 BC5 BC6 BC7 BC8BC4D0 D1 D2 D3 A13 A14 A15 A16B9 B12 B14 B15D5 D6D4C10
B11 B13A12E4E3E2E1 beam axis =0,0 h ~~ Fig. 2:
Segmentation in depth and η of the Tile Calorimeter modules in the barrel (left) and extended barrel (right).The bottom of the picture corresponds to the inner radius of the cylinder. The Tile Calorimeter is symmetricwith respect to the interaction point. The cells between two consecutive dashed lines form the first level triggercalorimeter tower. TileCal is a large hadronic sampling calorimeter using plastic scintillator as the active material and low-carbon steel (iron) as the absorber. Spanning the pseudorapidity region − . < η < .
7, the calorimeteris sub-divided into the barrel, also called long barrel (LB), in the central region ( − . < η < .
0) and thetwo extended barrels (EB) that flank it on both sides (0 . < | η | < . The pseudorapidity η is defined as η = − ln (cid:16) tan θ (cid:17) , where θ is the polar angle measured from the beam axis. Theazimuthal angle φ is measured around the beam axis, with positive (negative) values corresponding to the top (bottom) part ofthe detector. eadiness of the ATLAS Tile Calorimeter for LHC collisions 3barrel and extended barrel cylinders are segmented into 64 wedges (modules) in φ , corresponding to a ∆ φ granularity of ∼ . λ (nuclear interaction length for protons) thick for the barrel and 1.5, 2.6and 3.3 for the extended barrel. The ∆ η segmentation for each module is 0.1 in the first two radial layersand 0.2 in the third layer (Figure 2). The φ , η and radial segmentation define the three dimensionalTileCal cells. Each cell volume is made of dozens of iron plates and scintillating tiles. Wavelengthshifting fibres coupled to the tiles on either φ edge of the cells, as shown in figure 3, collect the producedlight and are read out via square light guides by two different photomultiplier tubes (PMTs), each linkedto one readout channel. Light attenuation in the scintillating tiles themselves would cause a responsenon-uniformity of up to 40 % in the case of a single readout, for particles entering at different impactpositions across φ . The double readout improves the response uniformity to within a few percent, inaddition to providing redundancy. Photomultiplier
Wavelength-shifting fibreScintillator SteelSourcetubes
Fig. 3:
Schematic showing the mechanical assembly and the optical readout of the Tile Calorimeter, correspondingto a φ wedge. The various components of the optical readout, namely the tiles, the fibres and the photomultipliers,are shown. The trapezoidal scintillating tiles are oriented radially and normal to the beam line and are read out byfibres coupled to their non-parallel sides. In addition to the standard cells, the Intermediate Tile Calorimeter (ITC) covers the region 0 . < η < . . < η < . . < η < . η range of 2 . < | η | < .
85 and arereadout by the TileCal EB electronics. They are used mainly for triggering on collisions in the very early The ATLAS CollaborationChannels Cells Trigger OutputsLong barrel 5760 2880 1152Extended barrel 3564 1790 768Gap and crack 480 480 128MBTS 32 32 32Total 9836 5182 2080
Table 1:
Number of channels, cells and trigger outputs of the Tile Calorimeter. The gap and crack and MBTSchannels are readout in the extended barrel drawers. stage of LHC operation and for rate measurements of halo muons, beam-gas and minimum bias eventsduring the low-luminosity running.The Tile Calorimeter readout architecture divides the detector in four partitions, a definition that is widelyused in this paper. The barrel is divided in two partitions (LBA and LBC) by the plane perpendicularto the beam line and crossing the interaction point, and each of the two extended barrels is a separatepartition (EBA and EBC).The TileCal readout electronics is contained in “drawers” which slide into the structural girders at theouter radius of the calorimeter. Barrel modules are read out by two drawers (one inserted from each face)and extended barrel modules are read out by one drawer each. Each drawer typically contains 45 (32)readout channels in the barrel (extended barrel) and a summary of the channels, cells and trigger outputsin TileCal is shown in Table 1. The front-end electronics as well as the drawers’ Low Voltage Power Supplies (LVPS) are located onthe calorimeter itself and are designed to operate under the conditions of magnetic fields and radiation.One drawer with its LVPS reads out a region of ∆ η × ∆ φ = . × . . × . µ s. The pipeline memory can be adjusted in coarse timing steps of 25 ns.The digitisation timing of the ADCs can be adjusted in multiples of ∼ . Cs cal-ibrations (see Section 4) and also to measure the current from minimum bias proton-proton interactionsat the LHC. The integration period is approximately 14 ms and a 12-bit ADC is used for the readout.Adder boards are distributed along the drawer. Each adder board receives the analogue signals from up to The 16 reduced thickness extended barrel C10 cells are readout by only one PMT. Two extended barrel D4 cells are mergedwith the corresponding D5 cells and have a common readout. eadiness of the ATLAS Tile Calorimeter for LHC collisions 5six 3-in-1 cards corresponding to cells of the same η . The trigger signal corresponding to a “tower” (seeFig. 2) of cells with ∆ η × ∆ φ = . × . E miss T signatures. The signal from allfour gap and crack scintillators is also summed by the adder board and passed to the L1 calorimetertrigger. A second output of the adder boards (so-called muon output), that can be used at a later stageto reduce the muon background rates, contains only the signal from cells of the outermost calorimeterlayer. Presently a fraction of the muon outputs is used for carrying the MBTS signals to the L1 triggersystem. The detector performance and stability results exposed in this paper are based on calibration systems’data and random triggered events which cover extended periods from mid-2008 up to the end of 2009excluding the maintenance period between December 2008 and May 2009. The results from cosmicmuons and single beam are from the autumn 2008 data-taking period, with the exception of the singlebeam data for timing studies, for which the winter 2009 and spring 2010 data is also used.The Tile Calorimeter at the end of 2008 data-taking period was fully operational with approximately1.5 % dead cells. The majority of the dead cells were due to three drawers that were non-operationalbecause of power supply problems or data corruption, amounting to 60 cells or 1.2 %. The remainingdead cells were randomly distributed throughout TileCal. During the 2009 data-taking period there were48 unusable cells, fewer than 1 %. The number of dead L1 trigger towers is less than 0.5 % and they areuniformly distributed throughout the detector. For details on how non-operational cells are defined andthe breakdown of their problems for the 2009 data-taking, see Section 3.1.The cosmic data used for performance validation was collected mainly between September and Octo-ber 2008 using the full ATLAS detector, including the inner detector and muon systems, with aroundone million events used for the present paper. The cosmic trigger configuration during this run periodconsisted of L1 triggers from the muon spectrometer (both the Resistive Plate Chamber (RPC) and theThin Gap Chambers (TGC)), the L1 calorimeter trigger and the MBTS. For much of the cosmic rayanalysis discussed in Section 5, the data sample was selected by requiring a L1 trigger and at least onetrack reconstructed in the inner detector, from the Pixel, SemiConductor Tracker (SCT) and TransitionRadiation Tracker (TRT). The majority of the events came from the L1 muon spectrometer triggers.During this running period, the ATLAS magnets were run in four different configurations; no magneticfield, solenoid magnet on only, toroid magnet on only and both solenoid and toroid magnets on. Theresults exposed here were obtained with the full ATLAS fields on.From the single beam data used in this paper the ”splash” events and ”scraping” events are used fortime and energy studies. The former term is used for events occurring when the LHC beam hits theclosed tertiary collimators positioned 140 m up-stream of the detector and are characterised by millionsof high-energy particles arriving simultaneously in the ATLAS detector. The latter occur when the opencollimators are scraping the LHC beam, allowing a moderate number of particles to the detector.
The TileCal detector operated at the end of 2009 with 99.1 % of cells functional for the digital readoutand 99.7 % of trigger towers functional for the L1. The numbers and fractions of non-operational cells, See Ref. [2], Fig. 1.4, for details on the layout. See Ref. [2], Fig. 1.1, for details on the layout.
The ATLAS CollaborationPartition Masked Channels Masked Cells Dead Trigger TowersBarrel A-side 59 (2.05%) 23 (1.60%) 2 (0.3%)Barrel C-side 58 (2.01%) 25 (1.74%) 0 (0.0%)Ext. barrel A-side 6 (0.29%) 0 (0.00%) 2 (0.5%)Ext. barrel C-side 1 (0.05%) 0 (0.00%) 1 (0.3%)Total 124 (1.26%) 48 (0.93%) 5 (0.3%)
Table 2:
Summary of the number of masked channels and cells in TileCal as of November 9th, 2009. The numberof dead trigger towers quoted is towers that are non-operational due to problems in TileCal’s front-end electronics,not counting those related to LVPS (18 towers). h -1.5 -1 -0.5 0 0.5 1 1.5 f -3-2-10123 00.511.522.53 ATLAS
Fig. 4:
Position in η and φ of the masked cells representing the status on November 9th, 2009. The colourscorresponding to numbers 1,2,3 show the number of layers masked for this ( η , φ ) region. The non-integer numbersindicate that one readout channel of the cell is masked. channels and trigger towers in the four calorimeter partitions are shown in Table 2.The problematic channels belong to two categories: channels with fatal problems and channels with dataquality problems. The so-called fatal problems are channels deemed unusable and are masked for theoffline reconstruction and at the High Level Trigger (HLT). These channels include:1. 44 cells (88 channels) due to two drawers with non-functional LVPS.2. 10 channels with no response due to failures of one or more components in the readout chain, suchas 3-in-1 cards, PMTs or ADCs.3. 24 channels with digital data errors (17 channels with a high occurrence rate of corrupted data and7 with gain switching problems).4. 2 channels with high noiseThe position in ( η , φ ) as of November 2009 of the unusable masked cells as described above, are shownin Figure 4 and are summarised in Table 2. One can notice the majority of the masked cells concentratedin two non-functional front-end drawers.eadiness of the ATLAS Tile Calorimeter for LHC collisions 7Channels with data quality problems are flagged as such for the reconstruction, but they are not masked.These channels include:1. Channels with occasional data-corruption problems, mainly due to front-end electronics malfunc-tion or bad configuration. These are excluded from the reconstruction by checking a quality frag-ment in the data record on an event by event basis. A fraction of the channels can be recovered byresetting the front-end between LHC fills.2. Channels which cannot be calibrated with one of the calibration systems (see Section 4). Theseare flagged as poorly calibrated channels.3. Noisy channels, which are treated by describing appropriately in the database their higher-than-average noise level to take into account while reconstructing their energy.4. Channels where the response varies significantly over time. These are also flagged for the offlineuse as poor quality channels but their response can be corrected over time if the source of variationis understood. Typical cases include channels with varying response due to changes over time ofthe high voltage applied to the photomultipliers.The parameters that directly affect the measured response of a channel are the temperature in the drawerand the applied high voltage because the PMT gain depends on them. The PMT gain G is proportionalto V , where V is the applied high voltage (HV), and decreases with temperature by 0.2 % per ◦ C. Theoperating conditions of the detector have been constantly monitored online and recorded by the DetectorControl System (DCS). The operating values of voltages, currents, temperatures at the LVPS and at thefront-end have been very stable. Figure 5 gives a measure of the long term evolution of the high voltageapplied on the PMTs for two periods of 3 and 6 months separated by the maintenance period. The HVvalues, which are typically close to ∼
670 V, have shown on average a difference of 0.17 V with respectto the value set during intercalibration with an RMS of 0.37 V during the considered period. This averagestability within 0.4 V for the whole calorimeter represents a 0.4 % reproducibility in the gain of the PMTsdue to this factor alone. Figure 6 shows the stability of the temperature measured by a probe installed inone PMT block for the same period as for the HV measurements. The average over all the calorimeterPMT probes is 24 . ◦ C with an RMS of 0 . ◦ C for a period of 9 months interleaved by the maintenanceperiod.
The channel signal properties – pulse amplitude, time and pedestal – for all TileCal channels are recon-structed with the Optimal Filtering (OF) method [8], which makes use of weighted linear combinationsof the digitised signal samples (spaced by 25 ns). Due to the simplicity of its mathematical formulation,OF is implemented in the Digital Signal Processors (DSPs) of the ReadOut Driver boards (RODs) [9] andtherefore provides energy and time information to the HLT of ATLAS during the online data-taking. Atpresent, since the data-taking rate allows it, the seven digitised samples are also available offline for allthe events together with the results of the OF reconstruction from the RODs. The procedure to computethe energy (given by the amplitude A ) and time ( τ ) are given by the equations: A = n = ∑ i = a i S i τ = A n = ∑ i = b i S i (1)where S i is the sample taken at time t i ( i = . . . n ). The coefficients of these combinations, a i and b i ,known as the OF weights, are obtained from knowledge of the pulse shape and noise autocorrelation ma-trix, and are chosen in such a way that the impact of the noise to the calorimeter resolution is minimised.Figure 7 shows the pulse shape extracted from data taken at the testbeam, selecting a channel with a The ATLAS Collaboration Jul 08 Oct 08 Jan 09 Apr 09 Jul 09 Oct 09 Jan 10 H V m ea s u r ed - H V s e t [ V ] -0.4-0.3-0.2-0.100.10.20.30.40.50.6 ATLAS
Maintenanceperiod
EBAEBCLBALBC
HV [V]-2 -1 0 1 2 E v en t s / . V ATLAS
Mean 0.17RMS 0.37
Fig. 5:
Stability of the PMT high voltage with respect to its set value, averaging over all PMTs for two periods of3 and 6 months (left) separated by the maintenance period. The distribution of the differences of the measured andthe set HV values for all PMTs over the period considered is also shown (right).
Jul 08 Oct 08 Jan 09 Apr 09 Jul 09 Oct 09 Jan 10 T e m pe r a t u r e [ C ] Maintenanceperiod
ATLAS
EBAEBCLBALBC
Temperatures [C]22 22.5 23 23.5 24 24.5 25 25.5 26 N b m ea s u r e s / . C · Mean 24.1RMS 0.2
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Fig. 6:
Stability of the temperature, as measured at one PMT in each drawer, averaging over all drawers andpresented for two periods of 3 and 6 months separated by the maintenance period (left). The distribution of thevalues for individual drawers over the whole period is also shown (right). given value of deposited energy for each gain. This pulse shape is the reference used in the estimation ofthe OF weights.The reconstructed channel energy used by the HLT and offline is: E channel = A · C ADC → pC · C pC → GeV · C Cs · C Laser (2)The signal amplitude A , described in more detail above, represents the measured energy in ADC countsas in Eq. (1). The factor C ADC → pC is the conversion factor of ADC counts to charge and it is determinedfor each channel using a well defined injected charge with the CIS (Charge Injection System) calibrationsystem. The factor C pC → GeV is the conversion factor of charge to energy in GeV and it has been definedeadiness of the ATLAS Tile Calorimeter for LHC collisions 9at testbeam for a subset of modules via the response to electron beams of known momentum in the firstradial layer. This factor is globally applied to all cells after being adjusted for a dependence on the radiallayer (see Section 4.4). The factor C Cs corrects for residual non-uniformities after the gain equalisationof all channels has been performed by the Cs radioactive source system. The factor C Laser , not currentlyimplemented, corrects for non-linearities of the PMT response measured by the Laser calibration system.The derived time dependence of the last two factors will be applied to preserve the energy scale ofTileCal. The details of the calibration procedures are discussed in Section 4.The channel time, τ in equation (1), is the time difference between the peak of the reconstructed pulseand the peak of the reference pulse. The OF weights used in the reconstruction were calculated based onthis reference pulse shifted by a time phase that depends on each channel’s timing offsets measured withthe calibration systems (and single-beam data), the time-of-flight from the interaction point to that celland the hardware time adjustments mentioned in Section 2.1. Thus the reconstructed time τ should becompatible with zero for energy depositions coming from the interaction point. If the time residual is notwell known, for small deviations ( | τ | <
15 ns) the uncertainty of the reconstructed amplitude depends on τ through a well-defined parabolic function, that can be used for an energy correction at the level of theHLT or offline reconstruction.The OF results rely on having, for each channel, a fixed and known time phase between the pulse peak andthe 40 MHz LHC clock signal. This is not the case during the commissioning phase of the detector, wheresignals caused by cosmic rays are completely asynchronous with respect to the LHC clock. NeverthelessOF can still be applied in this case and an accurate reconstruction may be obtained by applying theproper weights for each event according to the time position of the signal. The estimation of the signaltime is achieved through an iterative procedure provided by a set of OF weights calculated at differentphases from −
75 ns to +
75 ns in steps of 1 ns. Figure 8 presents the relative difference between thereconstructed offline energy and the energy calculated in the DSPs for cosmic muon data and shows theeffect of the limited numerical precision of the DSPs. The results in the following sections are based onchannel energies reconstructed offline with the iterative procedure to define the phase.The Fit method is another signal reconstruction algorithm. It is based on a three parameter fit to theknown pulse shape function g ( t ) , as expressed by: S i = Ag ( t i − τ ) + ped (3)The meaning of the variables S i and t i and the parameters A and τ is the same as for the OF method,while ped is a free parameter that defines the baseline of the pulse. The Fit method is mathematicallyequivalent to OF in the absence of pile-up and noise, but it is not suitable for fast online signal processingin DSPs. Results from the Fit and OF methods were compared with testbeam data and were found to beequivalent [10]. Since the autumn of 2008 data-taking, the Fit method is used only for CIS calibrationdata, where the pulse is a superposition of charge-proportional and charge-independent components [10].The cell energy is the sum, and the cell time the average, of the respective measurements by the twocorresponding readout channels. In cases of single readout cells, or if one of the channels is masked out,the cell energy is twice the energy measured in the single available channel. The measurement of thecell’s energy is thus robust to failures in a single readout channel. The noise in TileCal was measured in dedicated bi-gain standalone runs with empty events (often calledpedestal runs) and in random triggered events within ATLAS physics runs (often called random triggers).The noise of each channel was derived from the seven digitised samples using the same method that wasused for signal reconstruction in cosmic and single beam events, i.e. using the OF with iterations. In Note that the level of noise depends on the OF method used. The non-iterative OF method results in lower noise than theOF with iterations by ∼ Time [ns]-60 -40 -20 0 20 40 60 80 100 120 [ N o r m a li z ed A DC c oun t s ] Low gainHigh gain
ATLAS
Fig. 7:
Pulse shape for high and low gain from testbeam data, used as reference for the OF weights calculation. [GeV] offl
E0 2 4 6 8 10 12 14 o ff l ) / E d s p - E o ff l ( E -0.006-0.004-0.00200.0020.0040.006 050100150200250 ATLAS
Fig. 8:
Difference between the reconstructed offline energy, E o f f l , and the energy given by the DSP E DSP relativeto E o f f l and as a function of E o f f l (in GeV), extracted from cosmic muon runs. eadiness of the ATLAS Tile Calorimeter for LHC collisions 11 A u g s t O c t s t D e c s t F e b s t A p r s t J u n s t A u g s t O c t s t D e c s t A u g s t O c t s t D e c s t F e b s t A p r s t J u n s t A u g s t O c t s t D e c s t D i g i t i s ed s a m p l e no i s e [ A DC c oun t s ] TileCal averageIndividual channel
ATLAS – Maintenance Period
Fig. 9:
Stability of average noise (RMS of the single digitised samples averaged over events and channels), inADC counts, for all channels and for an individual channel.
Figure 9 the evolution during the running periods of 2008 and 2009 of the average noise, in ADC counts,is shown for all channels and for an individual channel. The channel noise is estimated as the RMS of thesingle digitised samples averaged over the events in dedicated TileCal pedestal runs. The overall stabilityis better than 1 %.The cell noise in MeV as a function of η is shown in Figure 10 averaged over all modules in φ for cellsin a given η position. The cell noise is estimated as the RMS of the cell’s energy distribution using theiterative OF signal reconstruction in random triggered events during a physics run with LHC single beamin 2008. Different colours are used to indicate cells in different longitudinal layers. The noise valuesvary between 30 and 60 MeV. The channels with higher noise are principally at the proximity of theLVPS which are located at the outer boundaries of the TileCal barrel and extended barrel modules.The cell noise probability distribution is an important component in the ATLAS calorimeter’s energyclustering algorithm. It is determined from the cell energy in empty events recorded through the standardATLAS data acquisition chain within physics runs and it is characterised by the σ of a fitted singleGaussian to the energy ( E ) distribution. The ratio E / σ is used to judge if a cell has a noise-like or asignal-like energy deposition. Figure 11 shows the ratio E / σ for all TileCal cells (squares). One canobserve the existence of non-Gaussian tails that could lead to fake signal cells if a criterion of E / σ > σ ’s and the relative amplitudes are used to construct a probability density function on the basisof which a new “effective σ ” ( σ eff ) for every cell is defined at the significance level of 68.3 %. Theimprovement is shown in Figure 11 where the triangles represent the ratio E / σ eff for all the calorimetercells. One can observe that there are no tails when compared to a Gaussian fit (line) or to a toy MonteCarlo noise generator, that randomly attributes to cells energies from a single Gaussian model (circles).Thus the ratio E / σ eff can be safely used to distinguish signal from noise in a TileCal cell. This Section describes the calibration procedures and data sets used in TileCal to establish the referencedetector response. Furthermore, the calibration results obtained in the years 2008 and 2009, during the since the timing will be fixed by the LHC 40 MHz clock frequency. h -1.5 -1 -0.5 0 0.5 1 1.5 N o i s e pe r La y e r [ M e V ] ATLAS
Noise per LayerLayer ALayer BCLayer D
Fig. 10:
Average cell noise in random triggered events as a function of the cell η and radial layer. The noise isrepresented by the RMS of the cell’s energy distribution and the error bar shows its spread over all cells in the samepseudorapidity bin. eff s E/ -10 -8 -6 -4 -2 0 2 4 6 8 10 E v en t s ATLAS
Random triggered events, 2008
Data: 2 Gaussian modelData: 1 Gaussian modelSingle Gaussian modelFit: Gaussian
Mean 0.000463 – – Fig. 11:
Significance level of the cell energy as compared to noise (Energy/Gaussian σ ) using the single and thedouble Gaussian descriptions of noise in random triggered events. eadiness of the ATLAS Tile Calorimeter for LHC collisions 13 Fig. 12:
Flow diagram of the readout signal paths of the different TileCal calibration tools. The paths are partiallyoverlapping, allowing for cross-checks and an easier identification of component failures. commissioning of the Tile Calorimeter in the ATLAS cavern, and the cross-checks related to the currentunderstanding of its calibration are also discussed. The main objectives of the calibration procedures inTileCal are to:– Establish the global electro-magnetic (EM) scale and the uncertainty associated with it. The EMscale calibration factor converts the calorimeter signals, measured as electric charge in pC, to theenergy deposited by electrons, which would produce these signals.– Minimise, measure and correct the cell-to-cell variations at the EM scale.– Measure and correct the non-linearity of the calorimeter response.– Measure the average time offset between the signal detection and the collision time for everyreadout channel.– Monitor the stability of these quantities in time.The Tile Calorimeter calibrations systems treat different sections of the readout chain as illustrated inFigure 12. They provide:– Calibration of the initial part of the signal readout path (including the optics elements and thePMTs) with movable radioactive Cs γ -sources [11], hereafter to be called simply Cs.– Monitoring of the gains of the photomultipliers by illuminating all of them with a laser system [4,12].– Calibration of the front-end electronic gains with a charge injection system (CIS) [6].In order to detect non-uniformities or degradation in the detector elements (optical and otherwise), thecalibration systems are specified to meet a precision of 1 % on the measurement of the response of a cell.The number of channels that cannot be calibrated by each individual calibration system is well below1 %. This is additional to the number of channels that are unusable due to LVPS problems or otherissues not related to the given calibration system. In the following sections the performance distributionsappear sometimes with fewer channels due to the fact that not all could be available for all the calibrationperiods.The current calibration protocol includes a number of dedicated calibration runs performed with a fre-quency derived from experience gained during the detector commissioning. The CIS constants are very4 The ATLAS Collaboration High-gain Calibration [ADC counts / pC]76 78 80 82 84 86 88 N u m be r o f A DC C hanne l s Entries 9346Mean 81.36RMS 1.229
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Low-gain Calibration [ADC counts / pC]1.2 1.25 1.3 1.35 1.4 N u m be r o f A DC C hanne l s Entries 9468Mean 1.294RMS 0.01953
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Fig. 13:
Channel-to-channel variation of the high gain (left) and of the low gain (right) readout calibration constantsas measured by the CIS, prior to any correction. The measured HG/LG gain ratio of 62.9 corresponds to thenominal of 64 (see Section 2.1) within tolerances of individual electronics components. stable in time and are only updated twice per year. For monitoring and identification of bad channels,CIS runs are performed between physics runs twice per week. For monitoring, laser runs are also per-formed twice per week. The resulting laser constants will be used only for monitoring purposes until thestability of this calibration system is fully understood. The Cs scans are performed outside beam periods,with a periodicity of weeks or months, depending on the machine schedule since a full scan takes 6 to 8hours. Starting from 2010, every Cs run is expected to result in new constants that adjust the global EMenergy scale which will be updated accordingly. Laser runs accompany Cs runs in order to disentanglebetween changes related to the optical system and PMTs. Since the laser runs are more frequent than theCs scans, the former provide information on the PMT gain changes between two Cs scans.A dedicated monitoring system based on slow integrators [6] records signals in the Tile readout channelsover thousands of bunch crossings during the physics runs and is also a part of the Tile calibrationframework. As this measurement requires experience with collisions it is still being commissioned.
The circuitry for the Charge Injection system is a permanent part of each front-end electronics channel [6]and it is used to measure the pC/ADC conversion factor for the digital readout of the laser calibration andphysics data and to determine the conversion factor for the slow integrator readout, measured in ohms.To reconstruct the amplitude for each injected charge, a three-parameter fit is performed as described atthe end of Section 3, with the amplitude being one of the parameters of the fit [10]. To determine thevalues of the gains for each channel, dedicated CIS calibration runs are taken frequently, in which a scanis performed over the full range of charges for both gains. The typical channel-to-channel variation ofthese constants is measured to be approximately 1.5 %, as shown in Figure 13. This spread indicates thelevel of corrections for which the CIS constants are applied.The stability in time of the average high gain and low gain readout calibration constants from August2008 to October 2009 is shown in Figure 14 for 99.4 % of the total number of ADCs. The time stabilityof a typical channel is also shown for each gain. Over this period, the RMS variation for the high andlow gain detector-wide averages and for the single channels shown, is less than 0.1 %. The superimposedbands of ± . Time [months]14054.5 14220.5 14386.5 14552.5 H i gh ga i n C I S C a li b r a t i on [ A DC c oun t s / p C ] A u g O c t D e c F e b A p r J u n e A u g O c t H i gh ga i n C I S C a li b r a t i on [ A DC c oun t s / p C ] Maintenance Period
TileCal averageTypical channel 0.7% channel systematic uncertainty – ATLAS
Time [months]14054.5 14220.5 14386.5 14552.5 Lo w ga i n C I S C a li b r a t i on [ A DC c oun t s / p C ] A u g O c t D e c F e b A p r J u n e A u g O c t Lo w ga i n C I S C a li b r a t i on [ A DC c oun t s / p C ] Maintenance Period
TileCal averageTypical channel 0.7% channel systematic uncertainty – ATLAS
Fig. 14:
Stability in time of the average high gain (left) and low gain (right) readout calibration constants fromAugust 2008 to October 2009. mainly due to the uncertainty on the injected charge.The distributions of high gain and low gain readout calibration constants for individual ADC channelswere compared for the sample of channels calibrated during the TileCal standalone testbeam period of2002 to 2003 and for the full detector in the cavern in 2009. No significant change in the calibration con-stants was observed, thus limiting the contribution from the CIS calibration to the systematic uncertaintyon transferring the EM scale from testbeam to ATLAS to below 0.1 %.To determine the values of the gains for each channel for the current integrator readout, dedicated cal-ibration runs are periodically taken, in which a scan is performed over the full range of currents for allsix integrator gains. The channel gain is extracted as a slope from a 2-parameter fit performed on themeasured channel response in voltage to each applied current. The typical channel-to-channel variationof these integrator gain constants is measured to be approximately 0.9 %, as shown in Figure 15 (left)for the gain used during calorimeter calibration with the Cs radioactive source. The 12-bit ADCs used todigitise the PMT currents were produced in two unequal batches with about 2% difference in amplifiergains, which can be clearly seen in the distribution of the integrator gains in Figure 15 (left).The relative variation of the integrator gains used by the Cs calibration system is shown in the right partof Figure 15. The measurements in 95.9 % of the integrators performed at different dates are comparedto the reference measurements of January 2008. The error bars represent the dispersion of the individualchannel measurements relative to their reference values in the first run. The stability of individual chan-nels is better than 0.05 % while the stability of the average integrator gain is better than 0.01 % over theconsidered period of time of 26 months.The variation of the integrator gains for individual channels used in the Cs calibration system readoutfrom 2001 to 2009 was studied on the sample of channels calibrated in both instances. No significantchange in the calibration constants was observed over eight years. The contribution from the integratorgain calibration to the systematic uncertainty on setting the EM scale of TileCal in ATLAS as comparedto the testbeam was found to be below 0.2 %.6 The ATLAS Collaboration ] W Integrator gain used by Cs [M27.5 28 28.5 29 29.5 N u m be r o f c hanne l s ATLAS ] W Integrator gain used by Cs [M27.5 28 28.5 29 29.5 N u m be r o f c hanne l s R e l a t i v e I n t eg r a t o r ga i n v a r i a t i on [ % ] -0.25-0.2-0.15-0.1-0.05-00.050.10.150.20.25 J an M a r M a y J u l S ep N o v J an M a r M a y J u l S ep N o v J an M a r ATLAS
Gains variationReference data set R e l a t i v e I n t eg r a t o r ga i n v a r i a t i on [ % ] -0.25-0.2-0.15-0.1-0.05-00.050.10.150.20.25 Fig. 15:
Distribution of the integrator gain used by the Cesium calibration system is shown on the left. Relativestability over twenty-two months of the same integrator gain is shown on the right.
The Tile Calorimeter is equipped with a custom-made laser calibration system [12] dedicated to themonitoring and calibration of the Tile photomultiplier properties, including the gain and linearity of eachPMT. The frequency doubled infrared laser providing a 532 nm green light beam is located in the ATLASUSA15 electronics room, 100 m from the detector. The laser emits short pulses, which reasonablyresemble those from the physics signals, with a nominal energy of a few mJ. This power is sufficient tosimultaneously saturate all Tile readout channels, and thus to probe their linearity over the full readoutdynamic range. A dedicated set of optical elements insures proper attenuation, partial de-coherence andpropagation of the original light beam to every photomultiplier used in the Tile Calorimeter readout.This calibration system was commissioned until September 2009 and since then it is operating in a stableconfiguration. By varying the voltages applied to the photomultipliers it was shown that the systemsensitivity to the relative gain variations is of 0.3 % on data sets recorded over few hours. The long termstability of the laser calibration system is under study.The time stability of the PMT gains was evaluated using dedicated laser runs and averaging over 98.8 %of the TileCal channels. An estimation of the relative gain variation in time was based on the analysisof the shape of the distribution of the PMT responses to the signal induced by the laser system at manyinstances. The average gain variation as a function of time over 40 days is shown on Figure 16. Thisvariation is found to be within 1.0 % over the considered period of time. The displayed error bars of0.5 % account for both the statistical uncertainty and the systematic effects and are entirely dominatedby the latter. The systematic uncertainty comes from the limited reproducibility of the light intensityon the photomultipliers downstream of the full optical chain through which the laser beam propagatesto the detector. The design goal of the laser system is to monitor the relative gain stability with 0.5%accuracy for time periods of months to years. The results mentioned above set the precision with whichthe PMT response stability can be monitored by the laser system between two Cs scans that are typicallyone month apart and monitor the combined response of the optics elements and PMTs.Once the global variation of the laser signal is accounted for, the gain stability per individual channelcan be studied. A typical channel to channel variation for HG and LG is shown in Figure 17, where therelative gain variations for two laser calibration runs separated by 50 days are presented. The shadedsidebands represent channels with relative variation above 1 %. The observed RMS of 0.3 % (0.2 %)eadiness of the ATLAS Tile Calorimeter for LHC collisions 17
Time [day/month] P M T g l oba l ga i n v a r i a t i on [ % ] -1.5-1-0.500.511.522.53 LBALBCEBAEBC
ATLAS
Fig. 16:
Average PMT gain variation measured by the laser calibration system as a function of time over forty daysin 2009.
Channel variation [ % ]−4 −2 0 2 4 N u m be r o f c hanne l s pe r . % (cid:0)(cid:0)(cid:0)(cid:0)(cid:0)(cid:0)(cid:0)(cid:0)(cid:0)(cid:0)(cid:0)(cid:0)(cid:0)(cid:0)(cid:0)(cid:0)(cid:0)(cid:0)(cid:0)(cid:0)(cid:0)(cid:0)(cid:0)(cid:0)(cid:0)(cid:0)(cid:0)(cid:0)(cid:0)(cid:0)(cid:0)(cid:0)(cid:0) High gain = 0.28% s RMS = 0.31%
ATLAS
Channel variation [ % ]−4 −2 0 2 4 N u m be r o f c hanne l s pe r . % (cid:0)(cid:0)(cid:0)(cid:0)(cid:0)(cid:0)(cid:0)(cid:0)(cid:0)(cid:0)(cid:0)(cid:0)(cid:0)(cid:0)(cid:0)(cid:0)(cid:0)(cid:0)(cid:0)(cid:0)(cid:0)(cid:0)(cid:0)(cid:0)(cid:0)(cid:0)(cid:0)(cid:0)(cid:0) Low gain = 0.14% s RMS = 0.21%
ATLAS
Fig. 17:
Channel-to-channel variation of the relative gain of the photomultipliers for two Laser calibration runstaken in HG (LG) mode, shown on the left (right). in the HG (LG) is a convolution of residual fluctuations of the laser system and variations of the PMTresponse. Therefore, this RMS can be considered as an upper limit on possible stochastic variations inphotomultiplier gains.Once the intrinsic stability of the laser calibration system is understood, this system will be used tocalibrate the gain and linearity of each PMT. All the photomultipliers used in TileCal were characterised on their arrival from Hamamatsu at dedicated test benches withLED light sources. No PMT was found with non-linearity worse than 3 % up to 800 pC of collected charge.
Cs radioactive γ -source The Tile Calorimeter includes the capability of moving through each scintillator tile a Cs radioactive γ -source along the Z -direction of the ATLAS detector. Capsules containing the Cs sources with activitiesof about 330 MBq emitting 0.662 MeV γ -rays are hydraulically driven through a system of 10 km ofsteel tubes that traverses every scintillating tile in every module [13]. Three sources of similar intensityare deployed in the three cylinders of the Tile Calorimeter. When a capsule traverses a given cell, theintegrator circuit located on the 3-in-1 cards (Section 2.1), reads out the current signal in the PMTs. Thetotal area under the integrator current vs capsule position curve corresponding to the source path lengthin a cell, is calculated and normalised to the cell size. This estimator of the cell response to Cs is usedthroughout this Section.Source scans provide the means to diagnose optical instrumentation defects [14] and to measure theresponse of each individual cell. The precision of the Cs based calibration was evaluated from thereproducibility of multiple measurements under the same conditions and was found to be about 0.3 %for a typical cell [11]. The precision is 0.5 % for the cells on the edge of the TileCal cylinders and a fewpercent for the narrow cells C10 and D4 in the gap region (see Figure 3). As discussed in Section 5.4,cosmic ray muons are used to cross-check the calibration factors for the cells of this type. The Cs calibration has proceeded in two distinct phases.– Photomultiplier gain equalisation to a chosen level of Cs response was performed for every individ-ual channel on the 11 % of production TileCal modules that were tested with particle beams during2001-2004 [10]. The next step was to measure the numerical value for the fixed EM scale withelectron beams. With the electrons entering the calorimeter modules at an incidence angle of 20 ◦ ,the average cell response normalised to beam energy was measured to be ( . ± . ) pC/GeV,defining the TileCal EM scale factor. This factor was determined for the cells of the first layer andpropagated via the gain equalisation to all the other cells. The RMS spread of ( . ± . ) % wasfound to be due to local variations in individual tile responses and tile-fibre optical couplings. Theabove two steps effectively resulted in setting the cell EM scale in the subset of TileCal modulesexposed to electron beams.– The second phase in the calibration was to reproduce the above PMT gain equalisation on the fullset of the Tile Calorimeter modules in the ATLAS environment and to transfer via the Cs responsethe EM scale factor as defined in the testbeam. This took place in the second half of 2008. In somecases the PMT gain is intentionally higher by 20 % (D0, D1, D2, D3, D4 and C10 cells) in order toimprove on signal to noise ratio for the detection of muons (see also Section 5.1). For the centralbarrel cells of the third radial layer this improvement will facilitate their possible usage in the L1muon trigger. The EM scale for these cells is recovered by applying appropriate corrections to thecell energy reconstruction.To set the EM scale as defined at the testbeam, the target response to Cs for 2008 and 2009 was definedas the response measured at the testbeam scaled by the ratio of the activities of the testbeam source tothe sources used in the cavern. These ratios were measured by intercalibrating the sources using twoTileCal modules that are kept outside the experimental hall. The source activity decay time between thetestbeam and the ATLAS scans was taken into account. By adjusting PMT gains in order to have equalresponse to Cs between the testbeam and the ATLAS setup, the numerical factor that converts charge toGeV is preserved. It is evident that the comparison of the source activities is of utmost importance inorder to preserve the absolute energy scale as set with electrons.eadiness of the ATLAS Tile Calorimeter for LHC collisions 19Source Location in 2009 Activity in Measured activity,April 2009 ( ± . ± . . ± . . ± . . ± . Table 3:
Activity of five
Cs radioactive sources as of April 2009, and ratios with respect to the reference sourceRP3713 of the measured activities averaged over all data sets collected in the spring of 2009. Source RP3713 wasused in calibrations during the test beam period. Source RP3712, kept in Building 175, is used for ageing tests.
Five
Cs radioactive sources of different ages and activities were used over the last years. Threesources are currently used in the ATLAS cavern and two different sources were used for checks oninstrumentation quality and for the calibration at the testbeam. In spring of 2009, one long barrel andone extended barrel module were scanned sixty times under the same conditions with all five radioactivesources. With the reproducibility of a single measurement better than 0.1 %, a full set of ratios of thesource activities was evaluated with the precision of 0.05 %. The results for these ratios after averagingover all data sets available are shown in the last column of Table 3. It should be noted that the thirdcolumn of the table gives an initial estimation of the activities as measured by the manufacturer witha ±
15% uncertainty. We plan to exchange the sources between the Tile Calorimeter cylinders in thecavern for future checks on reproducibility of the responses and also to monitor the ratios of the sourceactivity in time.
Comparing the EM scale response between the testbeam and full detector, the magnetic field configura-tion has to be considered. During the testbeam no magnetic field was present while during data-takingin ATLAS, TileCal operates in the presence of magnetic field. The calorimeter iron, mainly the girdervolume at the outer radius, serves as the flux return of the solenoid field. The general behaviour of iron-scintillator calorimeters in magnetic field is known from other experiments [15–17]. A small increase inthe scintillator light yield, which also varies modestly over a broad range of the applied field is expected.The impact of the full ATLAS magnetic field on the Tile Calorimeter response was studied using the Cscalibration system. The ratio of the TileCal cell response to a radioactive Cs source in the full ATLASmagnetic field to its response to the Cs source without the field is given in Figure 18 (left) as a functionof η for two consecutive Cs runs. The cells in individual radial layers are shown with different symbols.The error bars represent the RMS of the above ratio over the sample of the sixty four identical cells inthe full φ range.As expected, the effect of magnetic field is stronger in the barrel partitions, where the flux of the solenoidfield return is the most intense, and where the increase in calorimeter response is on average ∼ . ∼ . response to radioactive Cs source with and without the full ATLAS magnetic field is shownin the right part of Figure 18 as function of φ . The vertical lines illustrate the positions of the Toroid coils.No clear structure in φ is observed, indicating that in the final ATLAS configuration the full magneticfield does not significantly affect the Tile Calorimeter response uniformity in φ . Starting from 2010, Cscalibrations will be exclusively based on the data taken with the full magnetic field. A cell through which the Toroid field return is the strongest. h -1.5 -1 -0.5 0 0.5 1 1.5 / I M F I ATLAS
Module number0 10 20 30 40 50 60 / I M F I MF I - run taken 10/06/09 I ATLAS
Fig. 18:
Ratio of the TileCal cell response to the radioactive Cs source in full ATLAS magnetic field to the TileCalcell response to the Cs source without the field, shown as function of η (left). Ratio of the TileCal D3 cell responseto radioactive Cs source in full ATLAS magnetic field over its response to the Cs source without the field, shownas function of φ (right). The vertical lines indicate the position of the ATLAS toroid coils. Once the EM scale was established and reproduced in ATLAS, periodic scans are performed to monitorthe stability of the detector response to the radioactive source in time. This is the final step that insuresthe monitoring of the known EM scale in time.The Tile Calorimeter response to the Cs source as a function of time is shown in Figure 19. The firstscan was taken approximately two weeks after the original PMT gain equalisation in July 2008. Around55 calibration runs with the radioactive source are considered for the time period from August 2008 toFebruary 2010. The maintenance period of six months is indicated by the vertical lines on Figure 19 andis excluded from the studies. The very first points after the maintenance period correspond to the secondgain equalisation to the same target value, corrected for the expected decrease in the source activity intime, as indicated on the Figure. The average response to the radioactive sources in the four calorimeterpartitions is shown by the points of different colours. Since three sources with about 3 % difference intheir activity are used in the barrel and two extended barrel cylinders, the data points follow three distinctpaths in time. The error bars, which are always below 0.4 %, represent the RMS spread in responses overthe full set of channels in a given partition. The number of cells with unreliable Cs calibration or withunstable HV level is below 0.2 % of the total and they are excluded from the present study. The shadedbands along the lines indicate the level of reproducibility of the Cs measurements. The “MF” labelindicates that the corresponding Cs calibration run was taken with both the ATLAS toroid and solenoidfields on. The response increase due to magnetic field is larger in the barrel partitions. Details on themagnetic field effects were already discussed in Section 4.3.2.The relative deviation of the measured Cs response from the expected values due to the decrease inthe source activity is shown in Figure 20 (left) for the same set of the calibration runs reported above.Similarly, the maintenance period is excluded and the “MF” marks are used when the magnetic fieldwas present during the calibration. The overall TileCal response to the radioactive sources follows theexpected Cs decay within 1 % when no magnetic field is applied. Within this 1 %, there is a visibledeviation from the expected decay line with increasing average response over time. A study of the Cscalibration procedure has been unable to attribute this increase to any subtle systematic effect, thereforeeadiness of the ATLAS Tile Calorimeter for LHC collisions 21 R es pon se [ a . u . ] LBA LBC EBA EBC
ATLAS
Maintenance period S e p N o v Ja n M a r M ay J u l S e p N o v Ja n C s d ecay c u r ve ( . % / yea r ) M F M F M F M F M F M F M F M F M F M F M F M F M F M F M F M F M F M F Fig. 19:
TileCal response to radioactive Cs sources in all four calorimeter partitions not corrected for the differencein the source activities as a function of time, averaging over all channels in a partition. The error bars represent theRMS spread in the responses of the sample of channels used. The “MF” symbol stands for the Cs calibration datataken with magnetic field on. ( M eas u r e d - E x p ec t e d ) / E x p ec t e d [ % ] -0.500.511.52 LBA LBC EBA EBC
ATLAS
Maintenance period S e p N o v Ja n M a r M ay J u l S e p N o v Ja n M F M F M F M F M F M F M F M F M F M F M F M F R M S / m ea n [ % ] LBA LBC EBA EBC
ATLAS
Maintenance period S e p N o v Ja n M a r M ay J u l S e p N o v Ja n M F M F M F M F M F M F Fig. 20:
Relative deviations of the TileCal response to Cs sources from the expected value for all four calorimeterpartitions, shown as a function of time (left). The ratio of RMS/mean of the TileCal response to radioactive Cssource in all four calorimeter partitions is shown as function of time (right). The “MF” symbol stands for the Cscalibration data taken in the magnetic field. The response is averaged over the channels of each partition. it is attributed to an increase in the detector response and it is under investigation. A conservative timedependent systematic uncertainty on the calibration of the EM scale of about 0.1 % per month is adoptedto account for this effect. It is estimated from the Cs data with no magnetic field within two periods of3 and 7 months in 2008, 2009 and 2010. The ratio of RMS/mean of the TileCal response to radioactiveCs sources in all four calorimeter partitions is shown as function of time in Figure 20 (right). The spreadin the measured Cs responses stays within 0.4 % over seventeen months indicating that the cell-to-cellintercalibration does not significantly change over this period of time. A small effect of the magneticfield on the Cs response spread is also clearly seen.
In this Section the understanding of the cell and layer intercalibration acquired from the testbeam andfrom calibration and single beam data is exposed. The intercalibration as validated by cosmic muons isexposed later in Section 5.3.1.The intercalibration with Cs sources in the ATLAS cavern reports channel response non-uniformities atthe level of ∼ . .
05 %, which is negligible. Altogether, the non-uniformities are given mostlyby the Cs system. The Cs scans of the whole Tile Calorimeter revealed the same level of uniformityamong individual optical elements in a cell as was measured during the optics instrumentation period.In the testbeam, a difference in the response to the Cs source and to particles was observed, increasing forlayers at larger radius [10]. This is due to the increasing size of the scintillator tiles for the external layers,and the resulting few percent layer miscalibration is accounted for by applying radial depth weights in theenergy scale calibration. The details of this procedure are described in Ref. [18]. Figure 21 (left) showsthe d E / d x for muons crossing the calorimeter parallel to the beam axis along its whole length fromeadiness of the ATLAS Tile Calorimeter for LHC collisions 23 Layer
A BC DA BC D M O P o f d E / d x [ M e V / mm ] ATLAS
Partition
EBC LBC LBA EBAEBC LBC LBA EBA M O P o f d E / d x [ M e V / mm ] ATLAS
Fig. 21:
The average energy measured in the single beam events recorded in September 2008. Left: averageenergy measured in individual radial layers after the radial layer corrections were applied (A is the inner radiuslayer). Right: the average energy measured in individual partitions, demonstrating good intercalibration betweenthem. scraping events in 2008. The d E / d x response for the muons from single beam events was estimated asthe peak of the fit to the convolution of a Landau function with a Gaussian (most probable value, referredthroughout the paper as MOP). Within a large statistical uncertainty, the response vs radial layer is flat.Given the fact that if the radial depth weights had not been applied the ratio of responses between layersA and D would be 1 . ∼ ∼ The EM scale of TileCal in ATLAS is set by adjusting the PMT HV to reproduce the calorimeter responseto the Cs radioactive source to the level it had during the tests with electron beams, where the EM scalewas determined and measured. After correcting for the expected decrease in the Cs source intensity, theHV levels currently set in ATLAS are expected to reproduce those used at the testbeam. Any differencein the detector parameters from that observed at the testbeam, if not fully understood or disproved andif it affects the EM scale setting, should be considered as the systematic uncertainty on the EM scaledetermination.The following sources of systematic uncertainties on the EM scale, as discussed in the previous Sections,are only related to the transfer of the EM calibration factor from the testbeam to ATLAS because theyoriginate from differences between the two setups:– 0.1 % from the calibration of the digital readout (HG, LG) by CIS.– 0.2 % from the calibration of the Cs readout gains. Events produced by the proton beam hitting the edge of the collimators located at about 140 m upstream ATLAS. The modules that were calibrated with the beams were carefully chosen to give a representative sample of the full TileCalmodule population. Thus no significant uncertainty on the EM scale is expected to result from data obtained with the electronbeams. ± . − − . − . ( . ± . ) V compared to those used during testbeam calibrations.This was due to the fact that the Cs system measured an increased response in June 2008 for the beamcalibrated modules with respect to their response in testbeams. If this response increase had not been adetector effect but an artifact of the Cs calibration system, a corresponding bias of -5.3 % (the true energybeing higher than the measured one) would have to be considered as an uncertainty for the cosmic datataken in autumn 2008. This would be added to the uncertainty from the observed increase of roughly0.1 % per month since June 2008, as mentioned above.The energy response from muons is a handle to assess this uncertainty or bias. A full description on theenergy scale analysis with cosmic and testbeam is given in Section 5.3. The comparison between thetestbeam and ATLAS EM scale is performed via the double ratio of d E / d x Data/MC ratios of cosmicover testbeam muons for LB modules. In other words, the agreement of data to the MC energy scalebetween testbeam and ATLAS is compared. Table 6 presents the values and the uncertainties of theabove mentioned double ratio per layer. Among the calibration related uncertainties, the contributionsfrom the non-reproducibility of the response increase due to magnetic field and from the unexplainedresponse increase measured by the Cs during 2008 are comprised. The reported ratios show an agreementof the EM scale set in 2008 and the expected scale as it was transported from the testbeam within theuncertainty range. However, the possible calibration bias mentioned in the previous paragraph, thatwould be represented by a double ratio of 0 .
95, can be excluded only at a (cid:46) σ level.If the uncertainty coming from the reduced high voltage settings with respect to the testbeam is nottaken into account, the overall estimate of the EM scale systematic uncertainty from the calibrations is ( − . , + . ) in early 2010. This uncertainty is ( − . , + . ) for October 2008, the period in which the cosmic muon data of this paper werecollected. eadiness of the ATLAS Tile Calorimeter for LHC collisions 25 To allow for optimal reconstruction of the energy deposited in the calorimeter by the OF signal recon-struction method (see Section 3), the time difference between the digitising sampling clock and the peakof the PMT pulses must be minimised and measured with a precision of 1 ns. To achieve this, the clockphases in the DMUs in the front-end hardware (see Section 2.1) are adjusted in multiples of 0.1 ns. Ide-ally all PMT signals would be sampled at the peak but several factors limit the ability to do this. First,the clock phase is defined per digitiser board which corresponds to six readout channels. Second, onlyone clock phase can be defined for both gains and there is a 2.3 ns difference between the HG and LGpulse peaks. Therefore in the front-end hardware, the accuracy of phase synchronisation for individualchannels is limited to be within 3 ns. Any residual time differences between the clock phase and thepulse peak are measured for each channel and accounted for in the OF signal reconstruction algorithm.The time phase and the residual offsets for all channels can be measured using the laser calibrationsystem, cosmic-ray events, beam splash and collision events. What is exposed in this Section is theprocedure to only pre-set the timing in order to synchronise the detector with the trigger signals and withthe other detectors prior to the final detailed adjustments, to be carried out with collisions data.Prior to beam, the laser was the primary source used to measure the channel timing. Since the laserlight is asynchronous with respect to the clock, a single reference channel in each partition was selectedand all other channels’ timing was defined with respect to that reference [19]. The timing precision forchannels in the same module is 0.6 ns for 99 % of the Tile Calorimeter readout channels. In addition, themean time difference between the HG and the LG was measured to be ( . ± . ) ns. One limitation inthe laser system for timing calibration is understanding the propagation time in the laser fibres from thelaser source to the PMTs. For this reason, the inter-partition timing and global timing with respect to therest of ATLAS were coarsely set using cosmic-ray data and more accurately using 2008 beam data.The timing calibration based on laser data was validated using beam splash events. These events con-tain millions of high-energy particles arriving simultaneously in the ATLAS detector. Since the totaldeposited energy is large, it is only possible to study the timing response in the LG. Using these events,the time intercalibration of individual channels in the same module was confirmed to be 0.6 ns.Figure 22 shows the cell time measured in beam splash events, averaged over the full range of theazimuthal angle φ for all cells with the same z -coordinate of ATLAS (along the beam axis). The visiblediscontinuities at Z = Z = ± . The calorimeter response to muons is an important issue since isolated muons will provide a signatureof interesting physics events in the LHC collisions phase. For example, semileptonic t ¯ t decays, theso-called “gold-plated” Higgs decay channel H → Z + Z and some SUSY processes involve high- p T This value takes into account 97 % of the TileCal channels. The timing for the remaining outliers was adjusted offline.
Z[mm]-6000 -4000 -2000 0 2000 4000 6000 T il e C e ll T i m e [ n s ] -40-30-20-1001020 Layer ALayer BCLayer D
ATLAS (a) 2008
Z[mm]-6000 -4000 -2000 0 2000 4000 6000 T il e C e ll T i m e [ n s ] -40-30-20-1001020 Layer ALayer BCLayer D
ATLAS (b) 2008
Z[mm]-6000 -4000 -2000 0 2000 4000 6000 T il e C e ll T i m e [ n s ] -10-8-6-4-20246810 Layer ALayer BCLayer D
ATLAS (c) 2009
Z[mm]-6000 -4000 -2000 0 2000 4000 6000 T il e C e ll T i m e [ n s ] -10-8-6-4-20246810 Layer ALayer BCLayer D
ATLAS (d) 2010
Fig. 22:
Timing of TileCal signals recorded with single beam data in September 2008 (a and b), November 2009(c) and February 2010 (d). The time is averaged over the full range of the azimuthal angle φ for all cells withthe same Z -coordinate (along beam axis), shown separately for the three radial layers. Corrections for the muontime-of-flight along the z axis are applied in the b), c) and d) figures, but not on the top left (a). eadiness of the ATLAS Tile Calorimeter for LHC collisions 27muons in their final states, while low- p T muons originate from B -meson decays [20]. In addition, sincethe interaction of muons with matter is well understood, the prediction of this response is reliable, andits investigation with data can provide information on the detector performance and intercalibration.The TileCal energy response performance was studied using cosmic muon data collected in 2008, withthe goal of verifying the calibration in terms of EM scale and its uniformity over the whole calorimeter.After an initial comparison of the muon energy signal and the corresponding noise in the same set of cells(in Section 5.1), the methods and results of the studies of muon response versus path length are described.These studies were based on the extrapolation into TileCal of cosmic muon tracks reconstructed by theInner Detector, which is described in Section 5.2.2. The performance of the energy response to testbeammuons was also checked at low energy, for comparison.Muon response results and comparison to Monte Carlo simulations are presented in Section 5.3. ThisSection focuses on several key issues: the response uniformity versus radial layer, η and φ , the prop-agation of the EM scale from testbeam to the full detector configuration in the ATLAS cavern, and adiscussion on the systematic uncertainties, such as the ones arising from possible biases of the muonresponse estimation with the muon momentum and path length. A separate Section 5.4 is devoted tocalibration of special TileCal cells (ITC, gap and crack scintillators).The measurement of the time-of-flight of particles in TileCal can be used either for background removal(cosmic and non-collision events) or physics analyses [21]. A good synchronisation of the TileCal cellsis important for that, and its validation with cosmic ray muons is described in Section 5.5. The TileCal readout system is designed so that even small signals induced by muons are well separatedfrom the noise. This feature has been demonstrated with testbeam data [10]. Nevertheless the perfor-mance has to be confirmed with data taken with the full ATLAS detector, since the environment is morenoisy and changes to the powering system have been made.This exercise was performed on a large statistics run, with the data sample described in Section 2.2:events from various first level triggers were required to have at least one reconstructed Inner Detectortrack. However, these tracks were not used in any further event or cell selection, for this study. Instead, adifferent method was used, based on track reconstruction using only TileCal data. This algorithm, namedTileMuonFitter, was developed for the data analysis and monitoring of TileCal in the cosmic muoncommissioning phase [22, 23]. It uses no external tracking information and uses the set of TileCal cellswith energy above a 250 MeV threshold to fit a straight line from the top to the bottom cells (it thereforealso ignores the track curvature inside the solenoid magnetic field). In order to reproduce as closelyas possible the signal from muons originating in physics collisions, a loose projectivity requirement wasimposed. Tracks were selected according to the coordinates of their intersection with the horizontal plane(within ±
400 mm) and to their angle with respect to the vertical, corresponding to a pseudorapidity rangeof 0 . < | η | < . . < | η | < .
4. Top andbottom module responses are considered as two independent entries, so the signal corresponds to that ofone module. The signal and noise distributions are well separated for both the total calorimeter responseand the last radial layer signal.In order to estimate the signal-to-noise ratio, the energy distribution is fit to the convolution of a Landaufunction with a Gaussian. Considering the peak of that convolution fit as the signal, and the RMS of therandom trigger distribution as the noise, the signal-to-noise ratio is then S / N =
29 for the total response8 The ATLAS Collaboration tower energy [GeV]−1 0 1 2 3 4 5 6 7 d E d N N ATLAS
D cell energy [GeV]−1 −0.5 0 0.5 1 1.5 2 2.5 3 d E d N N ATLAS
Fig. 23:
Example of the muon signal and corresponding noise for projective cosmic muons entering the barrelmodules at 0 . < | η | < .
4. Top and bottom modules are treated separately and the momentum range of the cosmicmuons was restricted to be between 10 and 30 GeV/ c . Left: the total energy summed up over selected cells. Right:the similar distribution of last radial compartments that can be eventually used to assist in muon identification. Thesignal (red) comes from the cosmic muon data sample (see text), the corresponding noise (black) is obtained withthe random trigger sample. and S / N =
16 for D cells. Since muons are the smallest energy signals that TileCal will measure, thesevalues show a good performance of the calorimeter. The obtained values are lower than for testbeam ,but the difference is consistent with a higher noise level in the ATLAS cavern and with a higher numberof cells being summed. A brief overview of the analysis methods applied to investigated data samples is provided in this Section.First, we briefly describe the dedicated testbeam (TB) studies with low-energy muons (Section 5.2.1).The algorithms and event selection used in the cosmic data analysis are then reported in Section 5.2.2.
The TB setup, operating conditions and results are summarised in Ref. [10]. Since most of the previousmuon TB results were obtained with 180 GeV beams and this energy is too high for the comparison withcosmic ray data, a dedicated study was performed with low-energy muons selected from a pion beam ata nominal energy of 20 GeV. These muons originate from pion decay, the distribution of their momentais calculated to range from 11.5 GeV/ c to 20 GeV/ c , peaking at around 17 GeV/ c . Data was collectedfrom ten runs with pion beams impinging on one barrel module at different projective incidences, from − . ≤ η ≤ − .
15 and 0 . ≤ η ≤ . In testbeam [10], muon beams at a nominal energy of 180 GeV were used for this study. Taking into account the 20 GeVto 180 GeV response ratio, the testbeam S / N ratios at 20 GeV for the tower and the D cells should amount to 42 and 17respectively. eadiness of the ATLAS Tile Calorimeter for LHC collisions 29– Contrary to muons, pions produce hadronic showers that leave signal also in towers surroundingthe one hit by the beam. This feature is exploited in the muon/pion selection – events with signalabove noise ( E (cid:38) σ noise ) in neighbouring towers were considered pions and were removed fromfurther analysis. Moreover, an upper limit on the response in the impact cell in the first calori-meter radial layer was imposed, in order to avoid pion showers with large electromagnetic showerfraction, whose typical lateral (in η × φ ) size is smaller than that of a cell.As the projective beams hit the centre of the given calorimeter tower, the muon response was summed uponly from cells in the impact tower. The selection criteria mentioned above guarantee a muon to impingeon the selected tower, therefore no further cut to reject noise events was needed.The muon track length in the given cell was considered as the radial size of that cell divided by the cosineof the beam incident angle. This approach is fully adequate for projective muons entering the calorimeterat a cell’s centre in both η and φ direction, see also Fig. 2.The Monte Carlo simulation of the TB setup takes into account the detailed detector and beam geometryas well as the momentum distribution of the incident muons. The performance of the calorimeter was analysed by taking advantage of the information provided bythe central tracking. This is an important handle for the study of the calorimeter cell response which issensitive to the muon path length and momentum.
Track extrapolation and event selection
Events were triggered at the first level trigger by RPC and TGC. The tracking information is ob-tained from the Inner Detector reconstruction, without further contribution from the Muon Spectrometer.Selected events are required to have one reconstructed track in the SCT volume. Events with recon-structed multiple tracks are rejected. Tracks in the TRT do not have η information and are not used inthe study. The quality of the tracks is enhanced by requiring at least eight hits in the silicon detectors(Pixel and SCT). The tracking requirements introduce some cut-off in the distributions of transverse andlongitudinal impact parameters. These are | d | ≤
380 mm and | z | ≤
800 mm, respectively. The tracks are extrapolated through the volume of the calorimeters using the tool described in Ref. [24],which uses propagation of the track parameters and covariances that take into account material andmagnetic field. Extrapolation is performed in both directions, along the muon momentum and oppositeto it. This allows to study the response of modules in the top and bottom part of the detector. Sincethe track parameters are measured in the centre the method could be sensitive to systematic differencestop/bottom.Figure 24 demonstrates the correct TileCal cell geometry description. It shows the response of cells inthe second layer as a function of the φ -coordinate measured at the inner-radius impact point in the givencell. The cells’ response average is computed over tracks along the η directions in the central barrelregion. The responses corresponding to cells of individual modules (width of ∆ φ ≈ .
1) are shown withsymbols of different colours/styles. The match with the nominal position of the cell edges, displayed byvertical lines, is evident. The total response summed over all modules is superimposed as well and it isreasonably uniform across φ .The alignment between Tracker and Calorimeter was investigated using tracks with a limited transverseimpact parameter ( | d | <
100 mm). The alignment between tracks and nominal cell edges in the second The transverse impact parameter is defined as the distance to the beam axis of the point of the closest approach of the trackto the coordinate origin. The longitudinal impact parameter is the z -coordinate (along the beam axis) of the same point. [rad] f Track -1.9 -1.85 -1.8 -1.75 -1.7 -1.65 -1.6 -1.55 C e ll R e s pon s e [ M e V ] ATLAS
Fig. 24:
Mean response of cells in the second layer as a function of track φ -coordinate for the bottom central regionof the calorimeter. Tracks with 10 < p <
30 GeV/ c were selected. The average response over all central regioncells in the given module is shown by symbols of different colours/styles, whereas the total response summed overall modules is shown with black full circles. Vertical lines denote nominal edges of the modules. layer of TileCal is within the selected bin size ( ∼ L >
20 cm.An upper limit of 30 GeV/ c on the muon momentum is used in the analysis in order to restrict themuon radiative energy losses which show considerable fluctuations and can have an impact on data/MCcomparisons. In a small fraction of events the cell response is compatible with the pedestal level althoughthe cells should be hit by a muon. The muon actually hits a neighbouring module. This is consistent withthe expected deviation from the muon trajectory due to multiple scattering. In order to limit this effectwe restrict the analysis to muons with momenta as measured in the Inner Detector larger than 10 GeV/ c and apply a fiducial volume cut requiring the track to be well within the module (that has a half width of ∆ φ = . | φ track − φ cell | < . . (4)In order to remove residual noise contribution, a cell energy cut of 60 MeV is applied.Muon tracks close to the vertical direction are badly measured in the Tile Calorimeter due to the strongsampling fraction variation caused by the vertical orientation of the scintillating tiles. To ensure morestable results, tracks are required to enter in the cells with a minimal angle with respect to η = | z inner − z outer | ≥ . (5)This cut has an appreciable effect only on very central cells, within the vertical coverage of the ID.Approximately 100 k data events satisfied the above mentioned selection criteria and were further anal-ysed. The corresponding statistics available in the MC sample was about twice higher.eadiness of the ATLAS Tile Calorimeter for LHC collisions 31 Track Path Length [mm]0 200 400 600 800 1000 R e s pon s e [ M e V ] ATLAS
Fig. 25:
Mean response of the barrel module BC cells as a function of track path length for tracks with 10 < p <
30 GeV/ c . A linear fit to the corresponding distribution of mean values is superimposed. The excess of events ataround the track path length of 840 mm (radial size of the barrel module BC cells) is a purely statistical effect,since most of the cosmic ray muons enter the calorimeter at small zenith angle. Performance checks
The track path length is the main handle to study the muon response. Figure 25 shows the responseof cells in the second layer as a function of the path length x . It includes cosmic events crossing the BCcells over the entire barrel and over all accepted angles. A clear edge at the path length of 840 mm isvisible in the figure. This represents the radial depth ∆ R of the BC layer cells. Since most cosmic rays arevertical, a large fraction of the muons crossing the central region have a reconstructed path length equalor slightly larger than the layer radius. This is very evident for all cells with a z -coordinate within thevertical coverage of the SCT detector | z | < E / d x ,is one of the quantities that can be used to study the cell/layers intercalibration. This will be discussed inmore detail in Section 5.3. In this subsection, the results of the calorimeter energy response studies carried out with cosmic muonsare reported. The main aim is to cross-check the energy scale set with testbeam and the calibration sys-tems, both in terms of the EM scale and of its uniformity across the detector cells. The uniformity of theresponse per cell and as a function of pseudorapidity and azimuthal angle is addressed in Section 5.3.1,while the layer intercalibration and EM scale issues are discussed in Sections 5.3.2 and 5.3.3 respectively.The energy response of TileCal to cosmic muons is probed by estimating the muon energy loss perunit length of detector material, which is obtained by dividing the energy measured by the path lengthcrossed in a given cell (calculated with the method described in Section 5.2.2). For simplicity, we callthis quantity d E / d x , even if this is not rigorous, since it is measured in a non-continuous way, and theTileCal cells are made of two different materials, with a direction-dependent sampling fraction.Our estimator for the muon response is the truncated mean of d E / d x , defined as the mean in which 1 %of the events in the high-energy tails of the distribution are removed (the number is rounded to the lowestinteger). The statistics of the data sample is limited and rare processes like bremsstrahlung or energetic δ -2 The ATLAS Collaboration [GeV] Track p10 d E / d x [ M e V / mm ] DataMC
EBA D5 Bottom(1.0% tr.mean)
ATLAS [GeV]
Track p10 D a t a / M C EBA D5 Bottom1.0% tr.meanFull mean.
ATLAS
EBA D5 Bottom1.0% tr.meanFull mean.
ATLAS
Fig. 26: (Left) Muon response d E / d x as a function of momentum as measured in the Inner Detector, estimatedwith the truncated mean for both data and Monte Carlo. (Right) Ratio of Data over Monte Carlo for the muonresponse d E / d x as a function of momentum, shown for the truncated and full mean. For both distributions theresponse is averaged over the D5 cells in the bottom of the extended barrel (A side). rays can cause large fluctuations of the full mean. The truncated mean is chosen since it is less sensitiveto high-energy tails in the cells’ response distribution, that are caused by the muon’s radiative energyloss. For testbeam, the truncated mean estimator has an additional advantage over the full mean, sinceit removes residual pion signal contamination. The truncated mean also removes muon events with verylarge energy deposits (high-energy radiation and/or muon nuclear interactions), therefore the muon/pionselection criterion (see Section 5.2.1) does not introduce any bias.The truncated mean of the energy distribution does not scale linearly with the path length, so there is asmall residual dependence of the d E / d x on the path length. This is evaluated as a systematic uncertaintyand, furthermore, it largely cancels when the ratio of Data/MC is considered.The dependency of the cell response to the muon momentum was investigated. As can be seen inFigure 26 (left), the response increases with the momentum as expected, by about 20 % between p =
10 GeV/ c and p =
100 GeV/ c and there is very good agreement between data and MC from 6 GeV/ c to ∼
100 GeV/ c . Figure 26 (right) shows that the MC simulations predict a steeper dependence on themuon momentum for the full mean, and some disagreement even for the truncated mean at the higherenergies, which could imply some imprecision in the modelling of the muon radiative energy losses.The real energy loss by muons is typically 10 % lower than the corresponding signal on EM scale andthe ratio, known as e / µ , slightly scales with energy [10, 25]. However, in this paper, the validation ofthe EM scale is carried out by comparing data and Monte Carlo, and response to cosmic and testbeammuons, so this correction factor is not necessary. The studies addressed here measure the response uniformity per cell in a layer, as a function of pseudo-rapidity η and azimuthal angle φ (i.e. per module). Since our estimator is the 1 % truncated mean, werequire a minimum of 100 events in each set – η or φ bin, or cell. For the η and φ uniformity analyses,the data is not divided in cells – all cells corresponding to that bin are accumulated and the truncationis applied to the single d E / d x distribution for that bin. This approach allows the usage of the largestpossible number of cells per bin while minimising biases from fluctuations in the tails. These resultseadiness of the ATLAS Tile Calorimeter for LHC collisions 33Layer Number of Fraction of RMS (MeV/mm)cells cells Data MCA 352 18 % 0.060 0.049BC 421 22 % 0.046 0.043D 316 38 % 0.052 0.048 Table 4:
The uniformity at the cell level for individual radial compartments. The listed values represent the RMSof the respective distribution of the truncated mean d E / d x for that layer, shown for data and Monte Carlo. Thenumber of cells considered, and the fraction of the total that they represent, are also shown. comprise all partitions, but exclude the ITC cells (see Section 5.4). In addition, we exclude from thisstudy two cells from the D layer with an unusually high d E / d x .Muons traverse cells in any direction and at any angle, so the local variations in the optics system (lightyield of individual tiles, tile-to-fibre couplings, etc.) are supposed to be averaged out. Uniformity per cell
The uniformity of the cell response is shown in Fig. 27 for each radial layer and the RMS values aresummarised in Table 4. The selection criteria, especially the requirement of 100 events per cell, limitthe number of measured cells to the values shown in the Figure and Table, but still a quite representativefraction of 23 % of the total cells is considered. The statistical population for the simulated and real dataused for this study is identical.The observed spread is the combination of different factors: statistical fluctuations, systematic errorsdue to the inherent limitations of measuring the cell response with the d E / d x of cosmic muons, and thespread in the cell EM scale inter-calibration.The Monte Carlo simulation has no variation in the quality of the optical components of the calorimeteror in the channel signal shape. Such variations are present in the data but it is difficult to disentanglebetween the spread due to them or to the statistical fluctuations from an underlying systematic due tothe measurement method. Since the MC shows an RMS in every layer compatible with that of data, itindicates that cells are well intercalibrated within layers.From the mean of the d E / d x distributions per layer it is observed that there is a response discrepancy of5.0 % between layer A and layer D (2.3 % between layer A and BC) for the cosmic muon data, an issuewhich is further discussed in Section 5.3.2.The variations as a function of pseudorapidity and azimuthal angle, presented in the following para-graphs, were studied separately in each layer, since they appear to be smaller than the dominating inter-layer differences just shown. Another reason is that the cosmic muons are in general non-projective,so most muon tracks cross the calorimeter in each radial layer at different values of η and/or φ . Deal-ing with the total response as a function of η , φ would require projective muons only, thus significantlylimiting the available statistics. The results are presented here relative to the average d E / d x . Uniformity per pseudorapidity
When investigating the uniformity as a function of pseudorapidity, the signal distribution includes allcells with the same azimuthal angle. A possible residual dependency of the muon momentum on thepseudorapidity of the detector cells (that could be due to the access shafts) was investigated. Figure 28(left) shows that the observed muon momentum distribution is harder than what expected by the MonteCarlo simulation, especially at high values of pseudorapidity. However, in the low momentum regionthat was selected for the analysis (between 10 and 30 GeV/ c , see Section 5.2.2), the agreement is muchbetter and the variations of momentum with η ( ∼
10 %) are quite tolerable for this study.4 The ATLAS Collaboration [MeV/mm]dxdE N u m be r o f C e ll s / . b i n ATLASLayer A
DataMean = 1.297RMS = 0.060No. of Cells = 352 MCMean = 1.330RMS = 0.049No. of Cells = 352 [MeV/mm]dxdE N u m be r o f C e ll s / . b i n ATLASLayer BC
DataMean = 1.326RMS = 0.046No. of Cells = 421 MCMean = 1.361RMS = 0.042No. of Cells = 421 [MeV/mm]dxdE N u m be r o f C e ll s / . b i n ATLASLayer D
DataMean = 1.361RMS = 0.052No. of Cells = 316 MCMean = 1.362RMS = 0.048No. of Cells = 316
Fig. 27:
Distribution of the truncated mean d E / d x per cell, shown separately for each radial layer A, BC and D, fordata and Monte Carlo. The momentum range of the cosmic muons was restricted to be between 10 and 30 GeV/ c . eadiness of the ATLAS Tile Calorimeter for LHC collisions 35 Fig. 28:
Momentum of the selected cosmic muon tracks as a function of pseudorapidity η , for both data andMonte Carlo. No momentum selection is applied in the left side distribution, while on the right, only tracks withmomenta within 10 GeV/ c and 30 GeV/ c are shown. The vertical error bars in the upper part show the RMS ofthe momentum distribution in each η bin; in the lower part the error bars represent the uncertainty on the data/MCvalue shown. The tracks identified in the ID are required to point to the cell centre, as specified in Equation (4), aswell as the other selection procedures of Section 5.2.2. The results are shown in Fig. 29 separately foreach radial compartment. It can be seen that, for all layers, the values for the long barrel (central region, | η | <
1) are scattered within a ± η , in the extended barrel, thestatistical uncertainties are larger due to worse coverage than in the central regions. Still these values arefor the most part distributed within a ± Uniformity vs. module
The uniformity over modules has also been investigated. The response in every module was integratedover all cells in the given radial layer. Studies combine all partitions, barrel and extended barrels.The results are shown in Fig. 30. Again the same cut on momentum 10 < p <
30 GeV/ c as measuredin the Inner Detector was applied. This condition plays two roles – apart from the reason mentioned inSection 5.2.2 it also ensures a similar initial momentum distribution in different φ -regions.Both experimental data and MC exhibit an essentially flat response as a function of azimuthal angle φ .A residual pattern observed with data matches the MC: this small increase of d E / d x in horizontal ( φ → , φ → ± π ) modules is likely due to a difference in muon momentum in events passing the selectioncriteria. Nevertheless, the data show a good uniformity over φ and, except a few cases in the horizontalregion, most modules are well within a ± φ ≈ π / φ ≈ − π /
2) modules appears to be within 1 %.
The results discussed in Section 5.3.1 show that the cells are reasonably intercalibrated within a givenlayer, while there are differences observed between individual layers. In order to better quantify thesedifferences, the layer response was calculated as the truncated mean of a single d E / d x distribution forall cells in a given layer. This approach reduces the statistical uncertainties, with respect to taking thetruncated mean in each cell or η , φ bin. In addition, only events in the bottom of the detector are used,to avoid a bias from the muon momentum cut – in this way, the muon momentum for all the events is6 The ATLAS Collaboration h -1.5 -1 -0.5 0 0.5 1 1.5 > d x d E / < d x d E ATLASLayer A
DataMC h -1.5 -1 -0.5 0 0.5 1 1.5 > d x d E / < d x d E ATLASLayer BC h -1.5 -1 -0.5 0 0.5 1 1.5 > d x d E / < d x d E ATLASLayer D
Fig. 29:
Uniformity of the cell response to cosmic muons, expressed in terms of normalised truncated meanof d E / d x , as a function of pseudorapidity η for each radial layer. The response is integrated over all cells ineach pseudorapidity bin in the given radial layer. The results for data are compared to MC simulations and bothare normalised to their averages for each layer. Data are shown with closed circles, open circles indicate MCpredictions. Statistical uncertainties only. Horizontal lines limiting a ± eadiness of the ATLAS Tile Calorimeter for LHC collisions 37 [rad] f -3 -2 -1 0 1 2 3 > d x d E / < d x d E ATLASLayer A
DataMC [rad] f -3 -2 -1 0 1 2 3 > d x d E / < d x d E ATLASLayer BC [rad] f -3 -2 -1 0 1 2 3 > d x d E / < d x d E ATLASLayer D
Fig. 30:
Uniformity of the cell response to cosmic muons, expressed in terms of normalised truncated mean ofd E / d x , as a function of azimuthal angle (module) for each radial layer. The response is integrated over all cellsin each module in the given radial layer. All partitions are combined. The results for data are compared to MCsimulations and both are normalised to their averages for each layer. Data are shown with closed circles, opencircles indicate MC predictions. Statistical uncertainties only. The gap around φ = ± E / d x have been carefully studied. For every contribution, the associated parameter was variedin the given range and the systematic uncertainty contribution was evaluated as half of the differencebetween the maximum and minimum resulting truncated mean, unless explicitly stated otherwise.The following contributions were identified:– As already shown in Fig. 26 (right), data and MC exhibit a slightly different behaviour in functionof the muon momentum. Because of this, the variation of the data/MC ratio over the analysis range(10 −
30 GeV/ c ) is considered as the systematic uncertainty due to the response dependence on themuon momentum.– As the muon momentum is measured in the Inner Detector located in the centre of ATLAS, the re-sponse in the top and bottom part of TileCal can be different. Although the difference is well below1 % (see also Section 5.3.1), we consider its half as the contribution to the systematic uncertainty.– Another contribution is associated with the residual dependence of the truncated mean on the pathlength. The truncated mean d E / d x was evaluated for several path length bins, and the abovementioned difference was calculated.– The truncation itself represents another source of systematic uncertainty, that is associated withuncertainties in the description of the energy response shape. The uncertainty was estimated bycomparing the resulting truncated mean of d E / d x for several values of truncation between 0 % and2.5 %. This contribution does not fully cancel for the Data/MC ratio due to the difference that isobserved in the tails of the d E / d x distribution between data and MC.– The impact of the noise cut was studied as well, varying it between 30 MeV and 90 MeV (approx-imately 1 σ and 3 σ , where σ is the average noise RMS). The associated systematics appears to bevery small.– The measured response was also compared for various triggers, whose efficiencies depend on themuon momentum and also event topology. The data triggered by TGC and RPC indicate a goodmatch within uncertainties, therefore the associated systematics is considered to be negligible withrespect to other contributions mentioned above.– The EM scale was transferred from testbeam to the ATLAS cavern by means of the Cs sourcecalibration procedure. Since the scale was set when the magnetic field was switched off and datawere collected with magnetic field on, the appropriate correction has to be applied. Moreover,the Cs data show a response increase with time (see Section 4.3). Most of the cosmic data wereacquired in September/October 2008, therefore we used the last Cs measurement with magneticfield on before the cosmic data taking to correct for both effects mentioned. The combined effectof these two corrections (magnetic field and response increase) amounts to − − . ± . ± . ± . ± . ± . ± . ± . ± . ± . ± . ± . ± . ± . ± . ± . ± . ± . ± . ± . ± . ± . ± . ± . ± . ± . ± . ± . ± . ± . ± . ± . ± . ± . ± . ± . ± . ± . ± . ± . ± . ± . ± . ± . ± . ± . ± . ± . ± . ± . ± . ± . ± . ± . ± . ± . ± . ± . ± . ± . ± . ± . ± . ± . ± . ± . ± . ± . ± . ± . ± . ± . ± . ± . ± . ± . ± . ± . ± . ± . ± . ± . ± . ± . ± . ± . ± . ± . ± . ± . ± . + . + . + . + . + . + . − . − . − . − . − . − . − − − − − − Data/MC ratio + . + . + . + . + . + . − . − . − . − . − . − . + . + . + . + . + . + . − . − . − . − . − . − . ± . ± . ± . ± . ± . ± . + . + . + . + . + . + . − . − . − . − . − . − . Table 5:
The individual contributions to the systematic uncertainty of the truncated mean d E / d x in cosmic muonData and Monte Carlo. The listed values correspond to the diagonal terms of the error matrix. Analyses wereperformed with the ID-track method. The uncertainties on the global EM scale factor are discussed in Section 4.5. . + . − . . ± .
05 1 . ± . . ± .
04 1 . ± .
05 1 . ± . . + . − . . ± .
02 1 . ± . . ± .
06 1 . ± .
06 1 . ± . . ± .
03 1 . ± .
06 1 . ± . . ± .
04 0 . ± .
03 0 . ± . . ± .
03 1 . ± .
04 1 . ± . . ± .
02 1 . ± .
03 1 . ± . . ± .
02 1 . ± .
04 1 . ± . ( Data / MC ) Cosmic muons, LB ( Data / MC ) TB, LB . ± .
03 0 . ± .
04 0 . ± . Table 6:
The truncated mean of d E / d x (MeV/mm, see text), measured with cosmic ray muons in barrel (LB) andextended barrel (EB), and projective testbeam muons. Results are shown for both data and Monte Carlo as wellas for each radial layer. For cosmic ray muons, only modules in the bottom part are used. Total uncertainties arequoted. For cosmic data the statistical component is negligible. The systematic uncertainty corresponds to thediagonal terms of the error matrix. [ M e V / mm ] d x d E Cosmic muons Long BarrelCosmic muons Extended BarrelTestbeam muons Long Barrel
ATLAS
LayerA BC D D a t a / M C Fig. 31:
The truncated mean of the d E / d x for cosmic and testbeam muons shown per radial compartment and, atthe bottom, compared to Monte Carlo. For the cosmic muon data, the results were obtained for modules at thebottom part of the calorimeter. The error bars shown combine in quadrature both the statistical and the systematicuncertainties, considering only the diagonal terms of the error matrix. The results on the longitudinal layer intercalibration are presented in Table 6 and displayed in Fig. 31, theerror bars representing the total uncertainty based on the quadratic sum of the statistical and systematicuncertainties.The differences in the cosmic muon response among individual layers are present even after correctingfor the residual dependencies on the path length, momentum, impact angle, impact point, by consideringthe ratio of data over Monte Carlo. The resulting values are strongly correlated, therefore the maximumdifference of 4 % between the individual measurements with the cosmic muon data indicates the layerresponse discrepancy.eadiness of the ATLAS Tile Calorimeter for LHC collisions 41
The ratio data/MC mentioned above also depends on the absolute EM scale of the MC simulated energyloss in the calorimeter. Due to the uncertainties in this quantity, the double ratio of data/MC, cosmicmuon/TB, is adopted for comparison of the muon response and hence the EM scale between cosmicand TB data in the long barrel. For testbeam data and Monte Carlo, the truncated mean of the d E / d x distribution was obtained for each run, and then averaged over all runs. These are the values alreadypresented in Table 6 and Figure 31. The evaluation of the systematic uncertainties is briefly descridedbelow.We consider the spread of the d E / d x values over the different incidence angles as the main uncertaintyof the measurement, an approach that effectively combines the statistical and part of systematic uncer-tainties. On top of them, we consider the following subdominant contributions:– The bias due to the truncation in the d E / d x distribution was estimated in the same way as forcosmic data (mentioned above).– The uncertainty in the global EM scale due to the non-calibrated integrators (see Sections 4.3and 4.4) at that time. This uncertainty applies only to data, not to Monte Carlo.The individual uncertainties were evaluated for each radial layer and the resulting total uncertainties,shown in Table 6, were obtained by summing the individual contributions in quadrature.The double ratio of data/MC, cosmic muons/TB, is presented in the last row of Table 6. The uncertaintycontributions are computed by propagating in quadrature the TB uncertainties just described and thecosmic muon uncertainties mentioned in the previous section, that only take into account the error matrixdiagonal terms. The EM scale measured with cosmic muons, relative to that determined at testbeam inthe long barrel, amounts to 1.01, 0.96 and 0.98 for the A, BC and D layers respectively. Since theuncertainties per layer are at most 4 %, these values are consistent with 1.0, showing that, within theprecision limits of the analysis, the propagation of the EM scale from testbeam to ATLAS was performedsuccessfully.It should be noted that the LHC collisions will provide extra tools to check the EM scale calibration.Isolated muons and single hadrons developing their shower only in TileCal will provide two data samplesfor which a direct comparison to the testbeam scale will be possible. Understanding the response of the intermediate Tile Calorimeter (ITC) and the gap and crack scintillators(see Section 2.1 and Figure 2) to cosmic ray muons is essential for their calibration. The gap and crackscintillators can not be calibrated using the Cs calibration source and therefore have arbitrary calibrationfactors applied to them. This study with cosmic muons gives the first clues for their in-situ performance.These detectors are calibrated in two steps. The first step is the intercalibration in φ among the cellsof the same detector type and to determine the calibration factors for each cell. The second step is theabsolute calibration and to determine a scale factor defined relative to the MC for each detector type.Since the absolute energy scale in the scintillators is not known, the simulation is used as a reference inthis case.The event selection follows the same procedures as indicated in Section 5.2.2, with the exception thatonly events with a single muon track with a momentum above 5 GeV are considered and that, for the ITCcells, the entry and exit points of the track in the cell must be separated by at least 4 cm in the z direction.2 The ATLAS CollaborationThese requirements accept 8 % of RPC triggered events, 80 % of TGC triggered events and 7 % of L1calorimeter triggered events. Problematic cells and scintillators are excluded in this analysis.The geometrical path length is defined as a straight line between the two surfaces of the cell or scintillator.The muon energy loss per unit path length is used to evaluate the response. It is referred to as d E / d x for the ITC cells (C10, D4), which have the same elementary structure as ordinary TileCal cells (asin Section 5.3). For the gap and crack scintillators (E1 – E4), the muon energy loss estimator is thesignal (expressed in units of charge) normalised to the muon path length through the scintillator and,for distinction, it is referred to as ∆ E / ∆ L . Figure 32 is an example of the d E / d x or ∆ E / ∆ L distributionfor the cells in one module for cosmic ray data and MC. The cells generally show good signal-to-noiseseparation except for crack scintillators (E3, E4). The signals in the crack scintillators are found to betoo small for good separation from noise distributions and the HV of the PMT has been accordinglyincreased. The noise distribution in the gap scintillators (E1, E2) in the data is mainly due to grooves andholes in these scintillators that accommodate the Cs source pipes.For each cell (scintillator), the d E / d x ( ∆ E / ∆ L ) distributions were fitted with the convolution of a Landaufunction with a Gaussian. The average and the RMS of the peak positions (MOP) of the fitted functionsare summarised in Fig. 33 and shown with the results from the MC. For comparison, results for theextended barrel cells D5 and B11 are also shown with ITC cells in the figure. Cells with insufficientstatistics or with poor fits are excluded and 30 % −
50 % of ITC cells and ∼
25% of gap scintillatorsremain.The average values indicate that the response for the ITC cells is consistent with the cell response ofordinary TileCal cells, which are well calibrated with the standard Tile Calorimeter calibration procedure.The response of the ITC cells is also consistent with MC to within ∼ ∼
10 % in ITCcells (C10 and D4), while in gap scintillators (E1, E2) the RMS values amount to 15 % −
20 %.Based on this study, no changes were made to the ITC cells since their response is consistent with theresponse of the ordinary Tile cells. For the gap scintillators, correction factors for φ intercalibration andglobal scale factors were measured relative to MC. As a result of this analysis, the HV values for thecrack scintillators (E3, E4) have been increased to improve the separation between signal and noise. Theexpected improvement has been verified. Before the start of the LHC in September 2008, cosmic muons provided the only way to verify theaccuracy of the time calibration of TileCal at the cell level. In addition to the online monitoring ofdetector synchronisation, that used distributions of average event time in function of position, detailedanalyses of the data, described in this section, were able to measure the timing corrections for a largefraction of the TileCal channels. These analyses, based on the measurement of the muon time-of-flightbetween the top and bottom cells, have been validated using the data from the 2008 LHC single beam.
Two methods have been developed to extract the time corrections using the cosmic data [26, 27]. Theyare based on the comparison of the time determined in the top and bottom modules with the time-of-flightof the cosmic muon through the detector.The iterative method [26] was successfully applied during the 2007 data takings. The very top barrel Cells or scintillators that, even though matched with extrapolated tracks, appear too noisy or show very small signal. eadiness of the ATLAS Tile Calorimeter for LHC collisions 43 dE/dX [MeV/mm] E n t r i e s ATLAS
D4 (EBC mod.49)DataMC
L [fC/mm] D E/ D E n t r i e s ATLAS
E1 (EBC mod.49)DataMC
L [fC/mm] D E/ D E n t r i e s ATLAS
E3 (EBC mod.49)DataMC dE/dX [MeV/mm] E n t r i e s ATLAS
C10 (EBC mod.49)DataMC
L [fC/mm] D E/ D E n t r i e s ATLAS
E2 (EBC mod.49)DataMC
L [fC/mm] D E/ D E n t r i e s ATLAS
E4 (EBC mod.49)DataMC
Fig. 32:
Responses of ITC cells (D4 and C10), gap scintillator cells (E1 and E2) and crack scintillator cells (E3and E4) to cosmic ray muons in EBC module 49. They are shown in terms of d E / d x for the ITC cells and ∆ E / ∆ L for the gap and crack scintillators. E E E E L P ea k po s i t i on [f C / mm ] D E / D EBCEBAEBC MCEBA MC
ATLAS B D D C d E / d X P ea k po s i t i on [ M e V / mm ] EBCEBAEBC MCEBA MC
ATLAS
Fig. 33:
Responses of gap and crack scintillators (left) and ITC cells (right) to cosmic muons. Shown are the aver-age values of the peak positions (MOP) of the fitted functions on the ∆ E / ∆ L and d E / d x distributions respectively.The vertical bars indicate the RMS values. f -3 -2 -1 0 1 2 3 T i m e o ff s e t s [ n s ] -15-10-5051015 LBC EBC LBA EBA
ATLAS f -3 -2 -1 0 1 2 3 T i m e o ff s e t s : bea m - c o s m i c m uon s [ n s ] -10-8-6-4-20246810 LBC EBC LBA EBA
ATLAS
Fig. 34: (Left) Average of the time corrections per module as measured with the global matrix method withcosmic muons, for all cells. (Right) Difference of those values with respect to the results from the 2008 singlebeam data, removing the cells from the first layer. Different symbols correspond to modules in different partitions,as indicated. module (LBA16) was taken as a reference and the time offsets of the other modules (taken as singlevalues for a whole module) were measured relative to this one. Since not all modules can be directlycalibrated with respect to the reference one, an iterative procedure has been adopted, determining firstthe time of modules in the bottom sector opposite to the reference. In subsequent steps, the time of othermodules in the top was determined relatively to those in the bottom already measured in the first step,and so on until all modules were analysed. The results of this method showed at an early stage that thelaser-based inter-module time offsets had an accuracy of about ± m and n are,respectively, the numbers of selected cells in the top and bottom part of the detector, and k is the numberof valid pairs (see selection criteria in next paragraph) between them, the problem can be posed in matrixform as: Mt = ∆ T (6)in which t is the ( m + n ) -size vector of unknown offsets, ∆ T is the k -size vector of measured timedifferences (averaged over all events, and corrected for time-of-flight). M is a ( m + n ) × k matrix, andeach line (of k ) contains 1 for the element of the top part and − M and ∆ T are divided by the standard deviation of the pair time difference measurement.Since k > ( m + n ) , this system of equations is overdetermined, so the (approximate) solution is the least-squares minimum of || Mt − ∆ T || .This method was applied to 0.5 M events from the RPC trigger sample of a long run taken in 2008.The event selection required to have at least one energy deposit above 250 MeV both on the top andbottom cells. For each event, cells were selected by requiring an energy between 200 MeV and 20GeV, and a time difference between both PMTs of less than 6 ns. A final selection required that at least5 events contribute to a cell pair average, and that the RMS of the measurements is smaller than 5 ns.eadiness of the ATLAS Tile Calorimeter for LHC collisions 45 Time offsets, 2008 single beam [ns]-20 -15 -10 -5 0 5 10 15 20 T i m e o ff s e t s , c o s m i c m uon s [ n s ] -20-15-10-505101520 020406080100120 ATLAS
Time offsets: 2008 single beam - cosmic muons [ns] -6 -4 -2 0 2 4 6 N u m be r o f c e ll s s ATLAS
Fig. 35:
Correlation (left) and difference (right) between the time corrections from cosmic muons and the 2008single beam results. The cells from the first radial layer were removed.
The efficiency of these selections is of 40 %, 75 % and 82 % for, respectively, the A, BC and D cells. Toavoid memory limitations due to the large number of pairs (more than 30k), the offset extraction wascarried out separately for four sets of pairs. To ensure consistency, these sets have a partial overlap, andthe results are integrated at the end. The results were compared with those obtained with the 2008 singlebeam data (see Section 4.6), which were taken very close in time (less than 1 month) to the cosmic muonrun analysed.
The average for each module of the cell offsets measured with the global matrix method is shown inFig. 34 (left) and the comparison with the single beam data is shown in Figs.34 (right) and 35.The results clearly show differences of 10 ns between each partition (Figure 34 left), but an otherwisegood uniformity, of 2 ns, for all the cells in the second and third radial layers within each partition(Figure 34 right). The results for the first layer are more scattered (this is reflected in the module averagedistributions, in particular for the EBA partition), in disagreement with the single beam measurements(see also Section 4.6). Due to the small size of the cells, the energy deposition with cosmic muons in thislayer is small (peaking at roughly half of the value for the second layer), and consequently the signal-to-noise ratio is worse. Since the single beam energy deposition is significantly larger, those results aremore reliable, and so only the cosmic muon results from the second and third layers are considered valid.It was expected to have differences between partitions, since the laser calibration had not been performedat this level. The difference of 5 – 8 ns for the first 8 modules of EBC (Figure 34 left, between 0 and0.8 in φ ) was unexpected, but confirmed with single beam data, and traced to an incorrect measurementof laser fibre lengths. So the inter-partition and inter-module results confirmed and validated the resultsfrom single beam, which were subsequently used to set the calibration time offsets, as described inSection 4.6. Within each partition, the agreement with the single beam data for the second and thirdlayers, both at the level of module averages and single cells, is about 1 ns. Since this is smaller than thespread of the average offsets, these results provide a measurement of the accuracy of the laser-based timecalibration, of about 2 ns. This is because the laser calibration data was taken in Tile standalone configuration, which has different delays than theglobal ATLAS online configuration
The Tile hadronic calorimeter of the ATLAS detector underwent extensive testing during its commis-sioning and cosmic muon data-taking periods. The calorimeter has 99.1 % (December 2009) of its cellsoperational and conditions that can affect the PMT gains have been monitored to be very stable over oneyear, such that no corrections are needed. The noise, being within the expectations and requirements,has a non-Gaussian component which has been taken into account in the reconstruction of clusters andphysics objects. The noise magnitude has been stable over time within 1 %.The electromagnetic energy scale has been transferred from 11 % of modules calibrated at testbeamto the full Tile Calorimeter in the ATLAS cavern setting by means of the TileCal calibration systems.The precision of all calibration systems is remarkable and has proven to follow the systems’ designrequirements. Regular calibration data-taking has demonstrated the stability of individual systems atlevels well below 1 %.The single beam data proved to be very useful in complementing the calibration systems for the syn-chronisation of the calorimeter cells. The timing intercalibration capability is at the level of 1 ns withina TileCal module and 2 ns within a partition. Cosmic muons provided an independent cross-check ofthe time calibration settings, having verified a large fraction of the second and third layer cells with 2 nsprecision.The analysis of the cosmic muon data has been a very useful validation procedure to assess the perfor-mance with particles at the full calorimeter scale and to compare with Monte Carlo expectations. Theseparation between signal and noise is very good, with an S/N ratio of ∼
29 for the sum of the three radiallayers. The cell response uniformity, as measured with the muon track d E / d x , is at the level of 4 . . . − We are greatly indebted to all CERN’s departments and to the LHC project for their immense efforts notonly in building the LHC, but also for their direct contributions to the construction and installation ofthe ATLAS detector and its infrastructure. We acknowledge equally warmly all our technical colleaguesin the collaborating Institutions without whom the ATLAS detector could not have been built. Further-more we are grateful to all the funding agencies which supported generously the construction and thecommissioning of the ATLAS detector and also provided the computing infrastructure.The ATLAS detector design and construction has taken about fifteen years, and our thoughts are with allour colleagues who sadly could not see its final realisation.We acknowledge the support of ANPCyT, Argentina; Yerevan Physics Institute, Armenia; ARC andDEST, Australia; Bundesministerium f¨ur Wissenschaft und Forschung, Austria; National Academy ofSciences of Azerbaijan; State Committee on Science & Technologies of the Republic of Belarus; CNPqand FINEP, Brazil; NSERC, NRC, and CFI, Canada; CERN; CONICYT, Chile; NSFC, China; COL-CIENCIAS, Colombia; Ministry of Education, Youth and Sports of the Czech Republic, Ministry ofIndustry and Trade of the Czech Republic, and Committee for Collaboration of the Czech Republic withCERN; Danish Natural Science Research Council and the Lundbeck Foundation; European Commis-eadiness of the ATLAS Tile Calorimeter for LHC collisions 47sion, through the ARTEMIS Research Training Network; IN2P3-CNRS and CEA-DSM/IRFU, France;Georgian Academy of Sciences; BMBF, DFG, HGF and MPG, Germany; Ministry of Education andReligion, through the EPEAEK program PYTHAGORAS II and GSRT, Greece; ISF, MINERVA, GIF,DIP, and Benoziyo Center, Israel; INFN, Italy; MEXT, Japan; CNRST, Morocco; FOM and NWO,Netherlands; The Research Council of Norway; Ministry of Science and Higher Education, Poland; FCTco-financed by QREN/COMPETE of European Union ERDF fund, Portugal; Ministry of Education andResearch, Romania; Ministry of Education and Science of the Russian Federation and State AtomicEnergy Corporation ROSATOM; JINR; Ministry of Science, Serbia; Department of International Sci-ence and Technology Cooperation, Ministry of Education of the Slovak Republic; Slovenian ResearchAgency, Ministry of Higher Education, Science and Technology, Slovenia; Ministerio de Educaci´on yCiencia, Spain; The Swedish Research Council, The Knut and Alice Wallenberg Foundation, Sweden;State Secretariat for Education and Science, Swiss National Science Foundation, and Cantons of Bernand Geneva, Switzerland; National Science Council, Taiwan; TAEK, Turkey; The Science and Technol-ogy Facilities Council and The Leverhulme Trust, United Kingdom; DOE and NSF, United States ofAmerica.
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A The ATLAS Collaboration
G. Aad , B. Abbott , J. Abdallah , A.A. Abdelalim , A. Abdesselam , O. Abdinov , B. Abi ,M. Abolins , H. Abramowicz , H. Abreu , B.S. Acharya , , D.L. Adams , T.N. Addy ,J. Adelman , C. Adorisio , , P. Adragna , T. Adye , S. Aefsky , J.A. Aguilar-Saavedra , a ,M. Aharrouche , S.P. Ahlen , F. Ahles , A. Ahmad , M. Ahsan , G. Aielli , , T. Akdogan ,T.P.A. ˚Akesson , G. Akimoto , A.V. Akimov , A. Aktas , M.S. Alam , M.A. Alam ,S. Albrand , M. Aleksa , I.N. Aleksandrov , C. Alexa , G. Alexander , G. Alexandre ,T. Alexopoulos , M. Alhroob , M. Aliev , G. Alimonti , J. Alison , M. Aliyev , P.P. Allport ,S.E. Allwood-Spiers , J. Almond , A. Aloisio , , R. Alon , A. Alonso , M.G. Alviggi , ,K. Amako , C. Amelung , A. Amorim , b , G. Amor´os , N. Amram , C. Anastopoulos ,T. Andeen , C.F. Anders , K.J. Anderson , A. Andreazza , , V. Andrei , X.S. Anduaga ,A. Angerami , F. Anghinolfi , N. Anjos , A. Annovi , A. Antonaki , M. Antonelli ,S. Antonelli , , J. Antos , B. Antunovic , F. Anulli , S. Aoun , G. Arabidze , I. Aracena ,Y. Arai , A.T.H. Arce , J.P. Archambault , S. Arfaoui , c , J-F. Arguin , T. Argyropoulos ,M. Arik , A.J. Armbruster , O. Arnaez , C. Arnault , A. Artamonov , D. Arutinov , M. Asai ,S. Asai , R. Asfandiyarov , S. Ask , B. ˚Asman , , D. Asner , L. Asquith , K. Assamagan ,A. Astvatsatourov , G. Atoian , B. Auerbach , K. Augsten , M. Aurousseau , N. Austin ,G. Avolio , R. Avramidou , C. Ay , G. Azuelos , d , Y. Azuma , M.A. Baak , A.M. Bach ,H. Bachacou , K. Bachas , M. Backes , E. Badescu , P. Bagnaia , , Y. Bai , T. Bain ,J.T. Baines , O.K. Baker , M.D. Baker , S Baker , F. Baltasar Dos Santos Pedrosa , E. Banas ,P. Banerjee , S. Banerjee , D. Banfi , , A. Bangert , V. Bansal , S.P. Baranov ,A. Barashkou , T. Barber , E.L. Barberio , D. Barberis , , M. Barbero , D.Y. Bardin ,T. Barillari , M. Barisonzi , T. Barklow , N. Barlow , B.M. Barnett , R.M. Barnett ,A. Baroncelli , A.J. Barr , F. Barreiro , J. Barreiro Guimar˜aes da Costa , P. Barrillon ,R. Bartoldus , D. Bartsch , R.L. Bates , L. Batkova , J.R. Batley , A. Battaglia ,M. Battistin , F. Bauer , H.S. Bawa , M. Bazalova , B. Beare , T. Beau , P.H. Beauchemin ,R. Beccherle , P. Bechtle , G.A. Beck , H.P. Beck , M. Beckingham , K.H. Becks ,A.J. Beddall , A. Beddall , V.A. Bednyakov , C. Bee , M. Begel , S. Behar Harpaz ,P.K. Behera , M. Beimforde , C. Belanger-Champagne , P.J. Bell , W.H. Bell , G. Bella ,L. Bellagamba , F. Bellina , M. Bellomo , A. Belloni , K. Belotskiy , O. Beltramello ,S. Ben Ami , O. Benary , D. Benchekroun , M. Bendel , B.H. Benedict , N. Benekos ,Y. Benhammou , D.P. Benjamin , M. Benoit , J.R. Bensinger , K. Benslama , S. Bentvelsen ,M. Beretta , D. Berge , E. Bergeaas Kuutmann , N. Berger , F. Berghaus , E. Berglund ,J. Beringer , P. Bernat , R. Bernhard , C. Bernius , T. Berry , A. Bertin , , M.I. Besana , ,N. Besson , S. Bethke , R.M. Bianchi , M. Bianco , , O. Biebel , J. Biesiada ,M. Biglietti , , H. Bilokon , M. Bindi , , A. Bingul , C. Bini , , C. Biscarat ,U. Bitenc , K.M. Black , R.E. Blair , J-B Blanchard , G. Blanchot , C. Blocker , A. Blondel ,W. Blum , U. Blumenschein , G.J. Bobbink , A. Bocci , M. Boehler , J. Boek , N. Boelaert ,S. B¨oser , J.A. Bogaerts , A. Bogouch , ∗ , C. Bohm , J. Bohm , V. Boisvert , T. Bold , e ,V. Boldea , V.G. Bondarenko , M. Bondioli , M. Boonekamp , S. Bordoni , C. Borer ,A. Borisov , G. Borissov , I. Borjanovic , S. Borroni , , K. Bos , D. Boscherini ,M. Bosman , H. Boterenbrood , J. Bouchami , J. Boudreau , E.V. Bouhova-Thacker ,C. Boulahouache , C. Bourdarios , A. Boveia , J. Boyd , I.R. Boyko , I. Bozovic-Jelisavcic ,J. Bracinik , A. Braem , P. Branchini , A. Brandt , G. Brandt , O. Brandt , U. Bratzler ,B. Brau , J.E. Brau , H.M. Braun , B. Brelier , J. Bremer , R. Brenner , S. Bressler ,D. Britton , F.M. Brochu , I. Brock , R. Brock , E. Brodet , C. Bromberg , G. Brooijmans ,W.K. Brooks , G. Brown , P.A. Bruckman de Renstrom , D. Bruncko , R. Bruneliere ,S. Brunet , A. Bruni , G. Bruni , M. Bruschi , F. Bucci , J. Buchanan , P. Buchholz ,A.G. Buckley , I.A. Budagov , B. Budick , V. B¨uscher , L. Bugge , O. Bulekov , M. Bunse ,0 The ATLAS CollaborationT. Buran , H. Burckhart , S. Burdin , T. Burgess , S. Burke , E. Busato , P. Bussey ,C.P. Buszello , F. Butin , B. Butler , J.M. Butler , C.M. Buttar , J.M. Butterworth , T. Byatt ,J. Caballero , S. Cabrera Urb´an , D. Caforio , , O. Cakir , P. Calafiura , G. Calderini ,P. Calfayan , R. Calkins , L.P. Caloba , D. Calvet , P. Camarri , , D. Cameron ,S. Campana , M. Campanelli , V. Canale , , F. Canelli , A. Canepa , J. Cantero ,L. Capasso , , M.D.M. Capeans Garrido , I. Caprini , M. Caprini , M. Capua , ,R. Caputo , C. Caramarcu , R. Cardarelli , T. Carli , G. Carlino , L. Carminati , ,B. Caron , f , S. Caron , G.D. Carrillo Montoya , S. Carron Montero , A.A. Carter , J.R. Carter ,J. Carvalho , g , D. Casadei , M.P. Casado , M. Cascella , , A.M. Castaneda Hernandez ,E. Castaneda-Miranda , V. Castillo Gimenez , N.F. Castro , a , G. Cataldi , A. Catinaccio ,J.R. Catmore , A. Cattai , G. Cattani , , S. Caughron , P. Cavalleri , D. Cavalli ,M. Cavalli-Sforza , V. Cavasinni , , F. Ceradini , , A.S. Cerqueira , A. Cerri ,L. Cerrito , F. Cerutti , S.A. Cetin , A. Chafaq , D. Chakraborty , K. Chan , J.D. Chapman ,J.W. Chapman , E. Chareyre , D.G. Charlton , V. Chavda , S. Cheatham , S. Chekanov ,S.V. Chekulaev , G.A. Chelkov , H. Chen , S. Chen , X. Chen , A. Cheplakov ,V.F. Chepurnov , R. Cherkaoui El Moursli , V. Tcherniatine , D. Chesneanu , E. Cheu ,S.L. Cheung , L. Chevalier , F. Chevallier , G. Chiefari , , L. Chikovani , J.T. Childers ,A. Chilingarov , G. Chiodini , V. Chizhov , G. Choudalakis , S. Chouridou , I.A. Christidi ,A. Christov , D. Chromek-Burckhart , M.L. Chu , J. Chudoba , G. Ciapetti , , A.K. Ciftci ,R. Ciftci , D. Cinca , V. Cindro , M.D. Ciobotaru , C. Ciocca , , A. Ciocio , M. Cirilli , h ,A. Clark , P.J. Clark , W. Cleland , J.C. Clemens , B. Clement , C. Clement , ,Y. Coadou , M. Cobal , , A. Coccaro , , J. Cochran , J. Coggeshall , E. Cogneras ,A.P. Colijn , C. Collard , N.J. Collins , C. Collins-Tooth , J. Collot , G. Colon , P. CondeMui˜no , E. Coniavitis , M.C. Conidi , M. Consonni , S. Constantinescu , C. Conta , ,F. Conventi , i , M. Cooke , B.D. Cooper , A.M. Cooper-Sarkar , N.J. Cooper-Smith ,K. Copic , T. Cornelissen , , M. Corradi , F. Corriveau , j , A. Corso-Radu ,A. Cortes-Gonzalez , G. Cortiana , G. Costa , M.J. Costa , D. Costanzo , T. Costin ,D. Cˆot´e , R. Coura Torres , L. Courneyea , G. Cowan , C. Cowden , B.E. Cox , K. Cranmer ,J. Cranshaw , M. Cristinziani , G. Crosetti , , R. Crupi , , S. Cr´ep´e-Renaudin ,C. Cuenca Almenar , T. Cuhadar Donszelmann , M. Curatolo , C.J. Curtis , P. Cwetanski ,Z. Czyczula , S. D’Auria , M. D’Onofrio , A. D’Orazio , C Da Via , W. Dabrowski , T. Dai ,C. Dallapiccola , S.J. Dallison , ∗ , C.H. Daly , M. Dam , H.O. Danielsson , D. Dannheim ,V. Dao , G. Darbo , G.L. Darlea , W. Davey , T. Davidek , N. Davidson , R. Davidson ,M. Davies , A.R. Davison , I. Dawson , R.K. Daya , K. De , R. de Asmundis ,S. De Castro , , P.E. De Castro Faria Salgado , S. De Cecco , J. de Graat , N. De Groot ,P. de Jong , L. De Mora , M. De Oliveira Branco , D. De Pedis , A. De Salvo ,U. De Sanctis , , A. De Santo , J.B. De Vivie De Regie , S. Dean , D.V. Dedovich ,J. Degenhardt , M. Dehchar , C. Del Papa , , J. Del Peso , T. Del Prete , ,A. Dell’Acqua , L. Dell’Asta , , M. Della Pietra , k , D. della Volpe , , M. Delmastro ,P.A. Delsart , C. Deluca , S. Demers , M. Demichev , B. Demirkoz , J. Deng , W. Deng ,S.P. Denisov , J.E. Derkaoui , F. Derue , P. Dervan , K. Desch , P.O. Deviveiros ,A. Dewhurst , B. DeWilde , S. Dhaliwal , R. Dhullipudi , l , A. Di Ciaccio , ,L. Di Ciaccio , A. Di Girolamo , B. Di Girolamo , S. Di Luise , , A. Di Mattia ,R. Di Nardo , , A. Di Simone , , R. Di Sipio , , M.A. Diaz , F. Diblen , E.B. Diehl ,J. Dietrich , T.A. Dietzsch , S. Diglio , K. Dindar Yagci , J. Dingfelder , C. Dionisi , ,P. Dita , S. Dita , F. Dittus , F. Djama , R. Djilkibaev , T. Djobava , M.A.B. do Vale ,A. Do Valle Wemans , T.K.O. Doan , D. Dobos , E. Dobson , M. Dobson , C. Doglioni ,T. Doherty , J. Dolejsi , I. Dolenc , Z. Dolezal , B.A. Dolgoshein , T. Dohmae ,M. Donega , J. Donini , J. Dopke , A. Doria , A. Dos Anjos , A. Dotti , , M.T. Dova ,A. Doxiadis , A.T. Doyle , Z. Drasal , M. Dris , J. Dubbert , E. Duchovni , G. Duckeck ,eadiness of the ATLAS Tile Calorimeter for LHC collisions 51A. Dudarev , F. Dudziak , M. D¨uhrssen , L. Duflot , M-A. Dufour , M. Dunford ,H. Duran Yildiz , R. Duxfield , M. Dwuznik , M. D¨uren , W.L. Ebenstein , J. Ebke ,S. Eckweiler , K. Edmonds , C.A. Edwards , K. Egorov , W. Ehrenfeld , T. Ehrich , T. Eifert ,G. Eigen , K. Einsweiler , E. Eisenhandler , T. Ekelof , M. El Kacimi , M. Ellert , S. Elles ,F. Ellinghaus , K. Ellis , N. Ellis , J. Elmsheuser , M. Elsing , D. Emeliyanov ,R. Engelmann , A. Engl , B. Epp , A. Eppig , J. Erdmann , A. Ereditato , D. Eriksson ,I. Ermoline , J. Ernst , M. Ernst , J. Ernwein , D. Errede , S. Errede , E. Ertel , M. Escalier ,C. Escobar , X. Espinal Curull , B. Esposito , A.I. Etienvre , E. Etzion , H. Evans ,L. Fabbri , , C. Fabre , K. Facius , R.M. Fakhrutdinov , S. Falciano , Y. Fang ,M. Fanti , , A. Farbin , A. Farilla , J. Farley , T. Farooque , S.M. Farrington ,P. Farthouat , P. Fassnacht , D. Fassouliotis , B. Fatholahzadeh , L. Fayard , F. Fayette ,R. Febbraro , P. Federic , O.L. Fedin , W. Fedorko , L. Feligioni , C.U. Felzmann ,C. Feng , E.J. Feng , A.B. Fenyuk , J. Ferencei , J. Ferland , B. Fernandes , m ,W. Fernando , S. Ferrag , J. Ferrando , V. Ferrara , A. Ferrari , P. Ferrari , R. Ferrari ,A. Ferrer , M.L. Ferrer , D. Ferrere , C. Ferretti , M. Fiascaris , F. Fiedler , A. Filipˇciˇc ,A. Filippas , F. Filthaut , M. Fincke-Keeler , M.C.N. Fiolhais , g , L. Fiorini , A. Firan ,G. Fischer , M.J. Fisher , M. Flechl , I. Fleck , J. Fleckner , P. Fleischmann ,S. Fleischmann , T. Flick , L.R. Flores Castillo , M.J. Flowerdew , T. Fonseca Martin ,J. Fopma , A. Formica , A. Forti , D. Fortin , D. Fournier , A.J. Fowler , K. Fowler ,H. Fox , P. Francavilla , , S. Franchino , , D. Francis , M. Franklin , S. Franz ,M. Fraternali , , S. Fratina , J. Freestone , S.T. French , R. Froeschl , D. Froidevaux ,J.A. Frost , C. Fukunaga , E. Fullana Torregrosa , J. Fuster , C. Gabaldon , O. Gabizon ,T. Gadfort , S. Gadomski , G. Gagliardi , , P. Gagnon , C. Galea , E.J. Gallas , V. Gallo ,B.J. Gallop , P. Gallus , E. Galyaev , K.K. Gan , Y.S. Gao , n , A. Gaponenko ,M. Garcia-Sciveres , C. Garc´ıa , J.E. Garc´ıa Navarro , R.W. Gardner , N. Garelli ,H. Garitaonandia , V. Garonne , C. Gatti , G. Gaudio , V. Gautard , P. Gauzzi , ,I.L. Gavrilenko , C. Gay , G. Gaycken , E.N. Gazis , P. Ge , C.N.P. Gee , Ch. Geich-Gimbel ,K. Gellerstedt , , C. Gemme , M.H. Genest , S. Gentile , , F. Georgatos , S. George ,A. Gershon , H. Ghazlane , N. Ghodbane , B. Giacobbe , S. Giagu , ,V. Giakoumopoulou , V. Giangiobbe , , F. Gianotti , B. Gibbard , A. Gibson ,S.M. Gibson , L.M. Gilbert , M. Gilchriese , V. Gilewsky , D.M. Gingrich , o , J. Ginzburg ,N. Giokaris , M.P. Giordani , , R. Giordano , , F.M. Giorgi , P. Giovannini ,P.F. Giraud , P. Girtler , D. Giugni , P. Giusti , B.K. Gjelsten , L.K. Gladilin , C. Glasman ,A. Glazov , K.W. Glitza , G.L. Glonti , J. Godfrey , J. Godlewski , M. Goebel , T. G¨opfert ,C. Goeringer , C. G¨ossling , T. G¨ottfert , V. Goggi , , p , S. Goldfarb , D. Goldin ,T. Golling , A. Gomes , q , L.S. Gomez Fajardo , R. Gonc¸alo , L. Gonella , C. Gong ,S. Gonz´alez de la Hoz , M.L. Gonzalez Silva , S. Gonzalez-Sevilla , J.J. Goodson ,L. Goossens , H.A. Gordon , I. Gorelov , G. Gorfine , B. Gorini , E. Gorini , , A. Goriˇsek ,E. Gornicki , B. Gosdzik , M. Gosselink , M.I. Gostkin , I. Gough Eschrich , M. Gouighri ,D. Goujdami , M.P. Goulette , A.G. Goussiou , C. Goy , I. Grabowska-Bold , r , P. Grafstr¨om ,K-J. Grahn , S. Grancagnolo , V. Grassi , V. Gratchev , N. Grau , H.M. Gray , s , J.A. Gray ,E. Graziani , B. Green , T. Greenshaw , Z.D. Greenwood , t , I.M. Gregor , P. Grenier ,E. Griesmayer , J. Griffiths , N. Grigalashvili , A.A. Grillo , K. Grimm , S. Grinstein ,Y.V. Grishkevich , M. Groh , M. Groll , E. Gross , J. Grosse-Knetter , J. Groth-Jensen ,K. Grybel , C. Guicheney , A. Guida , , T. Guillemin , H. Guler , u , J. Gunther , B. Guo ,L. Gurriana , Y. Gusakov , A. Gutierrez , P. Gutierrez , N. Guttman , O. Gutzwiller ,C. Guyot , C. Gwenlan , C.B. Gwilliam , A. Haas , S. Haas , C. Haber , H.K. Hadavand ,D.R. Hadley , P. Haefner , S. Haider , Z. Hajduk , H. Hakobyan , J. Haller , v , K. Hamacher ,A. Hamilton , S. Hamilton , L. Han , K. Hanagaki , M. Hance , C. Handel , P. Hanke ,J.R. Hansen , J.B. Hansen , J.D. Hansen , P.H. Hansen , T. Hansl-Kozanecka , P. Hansson ,2 The ATLAS CollaborationK. Hara , G.A. Hare , T. Harenberg , R.D. Harrington , O.M. Harris , K Harrison ,J. Hartert , F. Hartjes , A. Harvey , S. Hasegawa , Y. Hasegawa , S. Hassani , S. Haug ,M. Hauschild , R. Hauser , M. Havranek , C.M. Hawkes , R.J. Hawkings , T. Hayakawa ,H.S. Hayward , S.J. Haywood , S.J. Head , V. Hedberg , L. Heelan , S. Heim , B. Heinemann ,S. Heisterkamp , L. Helary , M. Heller , S. Hellman , , C. Helsens , T. Hemperek ,R.C.W. Henderson , M. Henke , A. Henrichs , A.M. Henriques Correia , S. Henrot-Versille ,C. Hensel , T. Henß , Y. Hern´andez Jim´enez , A.D. Hershenhorn , G. Herten ,R. Hertenberger , L. Hervas , N.P. Hessey , E. Hig´on-Rodriguez , J.C. Hill , K.H. Hiller ,S. Hillert , , S.J. Hillier , I. Hinchliffe , E. Hines , M. Hirose , F. Hirsch ,D. Hirschbuehl , J. Hobbs , N. Hod , M.C. Hodgkinson , P. Hodgson , A. Hoecker ,M.R. Hoeferkamp , J. Hoffman , D. Hoffmann , M. Hohlfeld , D. Hollander , T. Holy ,J.L. Holzbauer , Y. Homma , T. Horazdovsky , T. Hori , C. Horn , S. Horner , S. Horvat ,J-Y. Hostachy , S. Hou , A. Hoummada , T. Howe , J. Hrivnac , T. Hryn’ova , P.J. Hsu ,S.-C. Hsu , G.S. Huang , Z. Hubacek , F. Hubaut , F. Huegging , T.B. Huffman ,E.W. Hughes , G. Hughes , M. Hurwitz , U. Husemann , N. Huseynov , J. Huston , J. Huth ,G. Iacobucci , G. Iakovidis , I. Ibragimov , L. Iconomidou-Fayard , J. Idarraga , P. Iengo ,O. Igonkina , Y. Ikegami , M. Ikeno , Y. Ilchenko , D. Iliadis , T. Ince , P. Ioannou ,M. Iodice , A. Irles Quiles , A. Ishikawa , M. Ishino , R. Ishmukhametov , T. Isobe ,C. Issever , S. Istin , Y. Itoh , A.V. Ivashin , W. Iwanski , H. Iwasaki , J.M. Izen ,V. Izzo , B. Jackson , J.N. Jackson , P. Jackson , M.R. Jaekel , V. Jain , K. Jakobs ,S. Jakobsen , J. Jakubek , D.K. Jana , E. Jankowski , E. Jansen , A. Jantsch , M. Janus ,G. Jarlskog , L. Jeanty , I. Jen-La Plante , P. Jenni , P. Jeˇz , S. J´ez´equel , W. Ji , J. Jia ,Y. Jiang , M. Jimenez Belenguer , S. Jin , O. Jinnouchi , D. Joffe , M. Johansen , ,K.E. Johansson , P. Johansson , S Johnert , K.A. Johns , K. Jon-And , , G. Jones ,R.W.L. Jones , T.J. Jones , P.M. Jorge , b , J. Joseph , V. Juranek , P. Jussel ,V.V. Kabachenko , M. Kaci , A. Kaczmarska , M. Kado , H. Kagan , M. Kagan , S. Kaiser ,E. Kajomovitz , S. Kalinin , L.V. Kalinovskaya , S. Kama , N. Kanaya , M. Kaneda ,V.A. Kantserov , J. Kanzaki , B. Kaplan , A. Kapliy , J. Kaplon , D. Kar , M. Karagounis ,M. Karagoz Unel , M. Karnevskiy , V. Kartvelishvili , A.N. Karyukhin , L. Kashif ,A. Kasmi , R.D. Kass , A. Kastanas , M. Kastoryano , M. Kataoka , Y. Kataoka ,E. Katsoufis , J. Katzy , V. Kaushik , K. Kawagoe , T. Kawamoto , G. Kawamura , M.S. Kayl ,F. Kayumov , V.A. Kazanin , M.Y. Kazarinov , J.R. Keates , R. Keeler , P.T. Keener ,R. Kehoe , M. Keil , G.D. Kekelidze , M. Kelly , M. Kenyon , O. Kepka , N. Kerschen ,B.P. Kerˇsevan , S. Kersten , K. Kessoku , M. Khakzad , F. Khalil-zada , H. Khandanyan ,A. Khanov , D. Kharchenko , A. Khodinov , A. Khomich , G. Khoriauli , N. Khovanskiy ,V. Khovanskiy , E. Khramov , J. Khubua , H. Kim , M.S. Kim , P.C. Kim , S.H. Kim ,O. Kind , P. Kind , B.T. King , J. Kirk , G.P. Kirsch , L.E. Kirsch , A.E. Kiryunin ,D. Kisielewska , T. Kittelmann , H. Kiyamura , E. Kladiva , M. Klein , U. Klein ,K. Kleinknecht , M. Klemetti , A. Klier , A. Klimentov , R. Klingenberg , E.B. Klinkby ,T. Klioutchnikova , P.F. Klok , S. Klous , E.-E. Kluge , T. Kluge , P. Kluit , M. Klute ,S. Kluth , N.S. Knecht , E. Kneringer , B.R. Ko , T. Kobayashi , M. Kobel , B. Koblitz ,M. Kocian , A. Kocnar , P. Kodys , K. K¨oneke , A.C. K¨onig , S. Koenig , L. K¨opke ,F. Koetsveld , P. Koevesarki , T. Koffas , E. Koffeman , F. Kohn , Z. Kohout , T. Kohriki ,H. Kolanoski , V. Kolesnikov , I. Koletsou , J. Koll , D. Kollar , S. Kolos , w , S.D. Kolya ,A.A. Komar , J.R. Komaragiri , T. Kondo , T. Kono , x , R. Konoplich , S.P. Konovalov ,N. Konstantinidis , S. Koperny , K. Korcyl , K. Kordas , A. Korn , I. Korolkov ,E.V. Korolkova , V.A. Korotkov , O. Kortner , P. Kostka , V.V. Kostyukhin , S. Kotov ,V.M. Kotov , K.Y. Kotov , C. Kourkoumelis , A. Koutsman , R. Kowalewski , H. Kowalski ,T.Z. Kowalski , W. Kozanecki , A.S. Kozhin , V. Kral , V.A. Kramarenko , G. Kramberger ,M.W. Krasny , A. Krasznahorkay , J. Kraus , A. Kreisel , F. Krejci , J. Kretzschmar ,eadiness of the ATLAS Tile Calorimeter for LHC collisions 53N. Krieger , P. Krieger , K. Kroeninger , H. Kroha , J. Kroll , J. Kroseberg , J. Krstic ,U. Kruchonak , H. Kr¨uger , Z.V. Krumshteyn , T. Kubota , S. Kuehn , A. Kugel , T. Kuhl ,D. Kuhn , V. Kukhtin , Y. Kulchitsky , S. Kuleshov , C. Kummer , M. Kuna , J. Kunkle ,A. Kupco , H. Kurashige , M. Kurata , Y.A. Kurochkin , V. Kus , R. Kwee , A. La Rosa ,L. La Rotonda , , J. Labbe , C. Lacasta , F. Lacava , , H. Lacker , D. Lacour ,V.R. Lacuesta , E. Ladygin , R. Lafaye , B. Laforge , T. Lagouri , S. Lai , M. Lamanna ,C.L. Lampen , W. Lampl , E. Lancon , U. Landgraf , M.P.J. Landon , J.L. Lane ,A.J. Lankford , F. Lanni , K. Lantzsch , A. Lanza , S. Laplace , C. Lapoire , J.F. Laporte ,T. Lari , A. Larner , M. Lassnig , P. Laurelli , W. Lavrijsen , P. Laycock , A.B. Lazarev ,A. Lazzaro , , O. Le Dortz , E. Le Guirriec , E. Le Menedeu , A. Lebedev , C. Lebel ,T. LeCompte , F. Ledroit-Guillon , H. Lee , J.S.H. Lee , S.C. Lee , M. Lefebvre ,M. Legendre , B.C. LeGeyt , F. Legger , C. Leggett , M. Lehmacher , G. Lehmann Miotto ,X. Lei , R. Leitner , D. Lellouch , J. Lellouch , V. Lendermann , K.J.C. Leney , T. Lenz ,G. Lenzen , B. Lenzi , K. Leonhardt , C. Leroy , J-R. Lessard , C.G. Lester ,A. Leung Fook Cheong , J. Levˆeque , D. Levin , L.J. Levinson , M. Leyton , H. Li , X. Li ,Z. Liang , Z. Liang , y , B. Liberti , P. Lichard , M. Lichtnecker , K. Lie , W. Liebig ,J.N. Lilley , A. Limosani , M. Limper , S.C. Lin , J.T. Linnemann , E. Lipeles , L. Lipinsky ,A. Lipniacka , T.M. Liss , D. Lissauer , A. Lister , A.M. Litke , C. Liu , D. Liu , z , H. Liu ,J.B. Liu , M. Liu , T. Liu , Y. Liu , M. Livan , , A. Lleres , S.L. Lloyd ,E. Lobodzinska , P. Loch , W.S. Lockman , S. Lockwitz , T. Loddenkoetter , F.K. Loebinger ,A. Loginov , C.W. Loh , T. Lohse , K. Lohwasser , M. Lokajicek , R.E. Long , L. Lopes , b ,D. Lopez Mateos , aa , M. Losada , P. Loscutoff , X. Lou , A. Lounis , K.F. Loureiro ,L. Lovas , J. Love , P.A. Love , A.J. Lowe , F. Lu , H.J. Lubatti , C. Luci , ,A. Lucotte , A. Ludwig , D. Ludwig , I. Ludwig , F. Luehring , D. Lumb , L. Luminari ,E. Lund , B. Lund-Jensen , B. Lundberg , J. Lundberg , J. Lundquist , D. Lynn , J. Lys ,E. Lytken , H. Ma , L.L. Ma , J.A. Macana Goia , G. Maccarrone , A. Macchiolo , B. Maˇcek ,J. Machado Miguens , b , R. Mackeprang , R.J. Madaras , W.F. Mader , R. Maenner ,T. Maeno , P. M¨attig , S. M¨attig , P.J. Magalhaes Martins , g , E. Magradze , Y. Mahalalel ,K. Mahboubi , A. Mahmood , C. Maiani , , C. Maidantchik , A. Maio , q , S. Majewski ,Y. Makida , M. Makouski , N. Makovec , Pa. Malecki , P. Malecki , V.P. Maleev , F. Malek ,U. Mallik , D. Malon , S. Maltezos , V. Malyshev , S. Malyukov , M. Mambelli ,R. Mameghani , J. Mamuzic , L. Mandelli , I. Mandi´c , R. Mandrysch , J. Maneira ,P.S. Mangeard , L. Manhaes de Andrade Filho , I.D. Manjavidze , P.M. Manning ,A. Manousakis-Katsikakis , B. Mansoulie , A. Mapelli , L. Mapelli , L. March , J.F. Marchand ,F. Marchese , , G. Marchiori , M. Marcisovsky , C.P. Marino , F. Marroquim ,Z. Marshall , aa , S. Marti-Garcia , A.J. Martin , A.J. Martin , B. Martin , B. Martin ,F.F. Martin , J.P. Martin , T.A. Martin , B. Martin dit Latour , M. Martinez ,V. Martinez Outschoorn , A.C. Martyniuk , F. Marzano , A. Marzin , L. Masetti ,T. Mashimo , R. Mashinistov , J. Masik , A.L. Maslennikov , I. Massa , , N. Massol ,A. Mastroberardino , , T. Masubuchi , P. Matricon , H. Matsunaga , T. Matsushita ,C. Mattravers , ab , S.J. Maxfield , A. Mayne , R. Mazini , M. Mazur , J. Mc Donald ,S.P. Mc Kee , A. McCarn , R.L. McCarthy , N.A. McCubbin , K.W. McFarlane ,H. McGlone , G. Mchedlidze , S.J. McMahon , R.A. McPherson , j , A. Meade , J. Mechnich ,M. Mechtel , M. Medinnis , R. Meera-Lebbai , T.M. Meguro , S. Mehlhase , A. Mehta ,K. Meier , B. Meirose , C. Melachrinos , B.R. Mellado Garcia , L. Mendoza Navas ,Z. Meng , ac , S. Menke , E. Meoni , P. Mermod , L. Merola , , C. Meroni , F.S. Merritt ,A.M. Messina , J. Metcalfe , A.S. Mete , J-P. Meyer , J. Meyer , J. Meyer , T.C. Meyer ,W.T. Meyer , J. Miao , S. Michal , L. Micu , R.P. Middleton , S. Migas , L. Mijovi´c ,G. Mikenberg , M. Mikestikova , M. Mikuˇz , D.W. Miller , M. Miller , W.J. Mills ,C.M. Mills , A. Milov , D.A. Milstead , , D. Milstein , A.A. Minaenko , M. Mi˜nano ,4 The ATLAS CollaborationI.A. Minashvili , A.I. Mincer , B. Mindur , M. Mineev , Y. Ming , L.M. Mir , G. Mirabelli ,S. Misawa , A. Misiejuk , J. Mitrevski , V.A. Mitsou , P.S. Miyagawa , J.U. Mj¨ornmark ,T. Moa , , S. Moed , V. Moeller , K. M¨onig , N. M¨oser , W. Mohr , S. Mohrdieck-M¨ock ,R. Moles-Valls , J. Molina-Perez , J. Monk , E. Monnier , S. Montesano , , F. Monticelli ,R.W. Moore , C. Mora Herrera , A. Moraes , A. Morais , b , J. Morel , G. Morello , ,D. Moreno , M. Moreno Ll´acer , P. Morettini , M. Morii , A.K. Morley , G. Mornacchi ,S.V. Morozov , J.D. Morris , H.G. Moser , M. Mosidze , J. Moss , R. Mount ,E. Mountricha , S.V. Mouraviev , E.J.W. Moyse , M. Mudrinic , F. Mueller , J. Mueller ,K. Mueller , T.A. M¨uller , D. Muenstermann , A. Muir , Y. Munwes , R. Murillo Garcia ,W.J. Murray , I. Mussche , E. Musto , , A.G. Myagkov , M. Myska , J. Nadal ,K. Nagai , K. Nagano , Y. Nagasaka , A.M. Nairz , K. Nakamura , I. Nakano ,H. Nakatsuka , G. Nanava , A. Napier , M. Nash , ad , N.R. Nation , T. Nattermann ,T. Naumann , G. Navarro , S.K. Nderitu , H.A. Neal , E. Nebot , P. Nechaeva ,A. Negri , , G. Negri , A. Nelson , T.K. Nelson , S. Nemecek , P. Nemethy ,A.A. Nepomuceno , M. Nessi , M.S. Neubauer , A. Neusiedl , R.M. Neves , P. Nevski ,F.M. Newcomer , R.B. Nickerson , R. Nicolaidou , L. Nicolas , G. Nicoletti , B. Nicquevert ,F. Niedercorn , J. Nielsen , A. Nikiforov , K. Nikolaev , I. Nikolic-Audit , K. Nikolopoulos ,H. Nilsen , P. Nilsson , A. Nisati , T. Nishiyama , R. Nisius , L. Nodulman , M. Nomachi ,I. Nomidis , M. Nordberg , B. Nordkvist , , D. Notz , J. Novakova , M. Nozaki ,M. Noˇziˇcka , I.M. Nugent , A.-E. Nuncio-Quiroz , G. Nunes Hanninger , T. Nunnemann ,E. Nurse , D.C. O’Neil , V. O’Shea , F.G. Oakham , f , H. Oberlack , A. Ochi , S. Oda ,S. Odaka , J. Odier , H. Ogren , A. Oh , S.H. Oh , C.C. Ohm , , T. Ohshima ,H. Ohshita , T. Ohsugi , S. Okada , H. Okawa , Y. Okumura , T. Okuyama ,A.G. Olchevski , M. Oliveira , g , D. Oliveira Damazio , E. Oliver Garcia , D. Olivito ,A. Olszewski , J. Olszowska , C. Omachi , ae , A. Onofre , a f , P.U.E. Onyisi , C.J. Oram ,M.J. Oreglia , Y. Oren , D. Orestano , , I. Orlov , C. Oropeza Barrera , R.S. Orr ,E.O. Ortega , B. Osculati , , R. Ospanov , C. Osuna , J.P Ottersbach , F. Ould-Saada ,A. Ouraou , Q. Ouyang , M. Owen , S. Owen , A Oyarzun , V.E. Ozcan , K. Ozone ,N. Ozturk , A. Pacheco Pages , C. Padilla Aranda , E. Paganis , C. Pahl , F. Paige , K. Pajchel ,S. Palestini , D. Pallin , A. Palma , b , J.D. Palmer , Y.B. Pan , E. Panagiotopoulou , B. Panes ,N. Panikashvili , S. Panitkin , D. Pantea , M. Panuskova , V. Paolone , Th.D. Papadopoulou ,S.J. Park , W. Park , ag , M.A. Parker , F. Parodi , , J.A. Parsons , U. Parzefall ,E. Pasqualucci , A. Passeri , F. Pastore , , Fr. Pastore , G. P´asztor , ah , S. Pataraia ,J.R. Pater , S. Patricelli , , T. Pauly , L.S. Peak , M. Pecsy , M.I. Pedraza Morales ,S.V. Peleganchuk , H. Peng , A. Penson , J. Penwell , M. Perantoni , K. Perez , aa ,E. Perez Codina , M.T. P´erez Garc´ıa-Esta˜n , V. Perez Reale , L. Perini , , H. Pernegger ,R. Perrino , S. Persembe , P. Perus , V.D. Peshekhonov , B.A. Petersen , T.C. Petersen ,E. Petit , C. Petridou , E. Petrolo , F. Petrucci , , D Petschull , M. Petteni , R. Pezoa ,A. Phan , A.W. Phillips , G. Piacquadio , M. Piccinini , , R. Piegaia , J.E. Pilcher ,A.D. Pilkington , J. Pina , q , M. Pinamonti , , J.L. Pinfold , B. Pinto , b , C. Pizio , ,R. Placakyte , M. Plamondon , M.-A. Pleier , A. Poblaguev , S. Poddar , F. Podlyski ,L. Poggioli , M. Pohl , F. Polci , G. Polesello , A. Policicchio , A. Polini , J. Poll ,V. Polychronakos , D. Pomeroy , K. Pomm`es , P. Ponsot , L. Pontecorvo , B.G. Pope ,G.A. Popeneciu , D.S. Popovic , A. Poppleton , J. Popule , X. Portell Bueso , R. Porter ,G.E. Pospelov , S. Pospisil , M. Potekhin , I.N. Potrap , C.J. Potter , C.T. Potter , K.P. Potter ,G. Poulard , J. Poveda , R. Prabhu , P. Pralavorio , S. Prasad , R. Pravahan , L. Pribyl ,D. Price , L.E. Price , P.M. Prichard , D. Prieur , M. Primavera , K. Prokofiev , F. Prokoshin ,S. Protopopescu , J. Proudfoot , X. Prudent , H. Przysiezniak , S. Psoroulas , E. Ptacek ,J. Purdham , M. Purohit , ai , P. Puzo , Y. Pylypchenko , M. Qi , J. Qian , W. Qian , Z. Qin ,A. Quadt , D.R. Quarrie , W.B. Quayle , F. Quinonez , M. Raas , V. Radeka , V. Radescu ,eadiness of the ATLAS Tile Calorimeter for LHC collisions 55B. Radics , T. Rador , F. Ragusa , , G. Rahal , A.M. Rahimi , S. Rajagopalan ,M. Rammensee , M. Rammes , F. Rauscher , E. Rauter , M. Raymond , A.L. Read ,D.M. Rebuzzi , , A. Redelbach , G. Redlinger , R. Reece , K. Reeves ,E. Reinherz-Aronis , A Reinsch , I. Reisinger , D. Reljic , C. Rembser , Z.L. Ren ,P. Renkel , S. Rescia , M. Rescigno , S. Resconi , B. Resende , P. Reznicek , R. Rezvani ,N. Ribeiro , A. Richards , R. Richter , E. Richter-Was , a j , M. Ridel , M. Rijpstra ,M. Rijssenbeek , A. Rimoldi , , L. Rinaldi , R.R. Rios , I. Riu , F. Rizatdinova ,E. Rizvi , D.A. Roa Romero , S.H. Robertson , j , A. Robichaud-Veronneau , D. Robinson ,JEM Robinson , M. Robinson , A. Robson , J.G. Rocha de Lima , C. Roda , ,D. Roda Dos Santos , D. Rodriguez , Y. Rodriguez Garcia , S. Roe , O. Røhne , V. Rojo ,S. Rolli , A. Romaniouk , V.M. Romanov , G. Romeo , D. Romero Maltrana , L. Roos ,E. Ros , S. Rosati , G.A. Rosenbaum , L. Rosselet , V. Rossetti , L.P. Rossi , M. Rotaru ,J. Rothberg , D. Rousseau , C.R. Royon , A. Rozanov , Y. Rozen , X. Ruan , B. Ruckert ,N. Ruckstuhl , V.I. Rud , G. Rudolph , F. R¨uhr , F. Ruggieri , A. Ruiz-Martinez ,L. Rumyantsev , Z. Rurikova , N.A. Rusakovich , J.P. Rutherfoord , C. Ruwiedel , P. Ruzicka ,Y.F. Ryabov , P. Ryan , G. Rybkin , S. Rzaeva , A.F. Saavedra , H.F-W. Sadrozinski ,R. Sadykov , F. Safai Tehrani , , H. Sakamoto , G. Salamanna , A. Salamon ,M.S. Saleem , D. Salihagic , A. Salnikov , J. Salt , B.M. Salvachua Ferrando ,D. Salvatore , , F. Salvatore , A. Salvucci , A. Salzburger , D. Sampsonidis , B.H. Samset ,H. Sandaker , H.G. Sander , M.P. Sanders , M. Sandhoff , P. Sandhu , R. Sandstroem ,S. Sandvoss , D.P.C. Sankey , B. Sanny , A. Sansoni , C. Santamarina Rios , C. Santoni ,R. Santonico , , J.G. Saraiva , q , T. Sarangi , E. Sarkisyan-Grinbaum , F. Sarri , ,O. Sasaki , N. Sasao , I. Satsounkevitch , G. Sauvage , P. Savard , f , A.Y. Savine , V. Savinov ,L. Sawyer , ak , D.H. Saxon , L.P. Says , C. Sbarra , , A. Sbrizzi , , D.A. Scannicchio ,J. Schaarschmidt , P. Schacht , U. Sch¨afer , S. Schaetzel , A.C. Schaffer , D. Schaile ,R.D. Schamberger , A.G. Schamov , V. Scharf , V.A. Schegelsky , D. Scheirich ,M. Schernau , M.I. Scherzer , C. Schiavi , , J. Schieck , M. Schioppa , , S. Schlenker ,E. Schmidt , K. Schmieden , C. Schmitt , M. Schmitz , A. Sch¨onig , M. Schott ,D. Schouten , J. Schovancova , M. Schram , A. Schreiner , C. Schroeder , N. Schroer ,M. Schroers , J. Schultes , H.-C. Schultz-Coulon , J.W. Schumacher , M. Schumacher ,B.A. Schumm , Ph. Schune , C. Schwanenberger , A. Schwartzman , Ph. Schwemling ,R. Schwienhorst , R. Schwierz , J. Schwindling , W.G. Scott , J. Searcy , E. Sedykh ,E. Segura , S.C. Seidel , A. Seiden , F. Seifert , J.M. Seixas , G. Sekhniaidze ,D.M. Seliverstov , B. Sellden , N. Semprini-Cesari , , C. Serfon , L. Serin , R. Seuster ,H. Severini , M.E. Sevior , A. Sfyrla , E. Shabalina , M. Shamim , L.Y. Shan , J.T. Shank ,Q.T. Shao , M. Shapiro , P.B. Shatalov , K. Shaw , D. Sherman , P. Sherwood , A. Shibata ,M. Shimojima , T. Shin , A. Shmeleva , M.J. Shochet , M.A. Shupe , P. Sicho , A. Sidoti ,F Siegert , J. Siegrist , Dj. Sijacki , O. Silbert , J. Silva , al , Y. Silver , D. Silverstein ,S.B. Silverstein , V. Simak , Lj. Simic , S. Simion , B. Simmons , M. Simonyan ,P. Sinervo , N.B. Sinev , V. Sipica , G. Siragusa , A.N. Sisakyan , S.Yu. Sivoklokov ,J. Sjoelin , , T.B. Sjursen , K. Skovpen , P. Skubic , M. Slater , T. Slavicek , K. Sliwa ,J. Sloper , V. Smakhtin , S.Yu. Smirnov , Y. Smirnov , L.N. Smirnova , O. Smirnova ,B.C. Smith , D. Smith , K.M. Smith , M. Smizanska , K. Smolek , A.A. Snesarev ,S.W. Snow , J. Snow , J. Snuverink , S. Snyder , M. Soares , R. Sobie , j , J. Sodomka ,A. Soffer , C.A. Solans , M. Solar , J. Solc , E. Solfaroli Camillocci , , A.A. Solodkov ,O.V. Solovyanov , J. Sondericker , V. Sopko , B. Sopko , M. Sosebee , A. Soukharev ,S. Spagnolo , , F. Span`o , R. Spighi , G. Spigo , F. Spila , , R. Spiwoks , M. Spousta ,T. Spreitzer , B. Spurlock , R.D. St. Denis , T. Stahl , J. Stahlman , R. Stamen ,S.N. Stancu , E. Stanecka , R.W. Stanek , C. Stanescu , S. Stapnes , E.A. Starchenko ,J. Stark , P. Staroba , P. Starovoitov , J. Stastny , P. Stavina , G. Steele , P. Steinbach ,6 The ATLAS CollaborationP. Steinberg , I. Stekl , B. Stelzer , H.J. Stelzer , O. Stelzer-Chilton , H. Stenzel ,K. Stevenson , G.A. Stewart , M.C. Stockton , K. Stoerig , G. Stoicea , S. Stonjek ,P. Strachota , A.R. Stradling , A. Straessner , J. Strandberg , S. Strandberg , A. Strandlie ,M. Strauss , P. Strizenec , R. Str¨ohmer , D.M. Strom , R. Stroynowski , J. Strube ,B. Stugu , P. Sturm , D.A. Soh , am , D. Su , Y. Sugaya , T. Sugimoto , C. Suhr , M. Suk ,V.V. Sulin , S. Sultansoy , T. Sumida , X.H. Sun , J.E. Sundermann , K. Suruliz , ,S. Sushkov , G. Susinno , , M.R. Sutton , T. Suzuki , Y. Suzuki , I. Sykora , T. Sykora ,T. Szymocha , J. S´anchez , D. Ta , K. Tackmann , A. Taffard , R. Tafirout , A. Taga ,Y. Takahashi , H. Takai , R. Takashima , H. Takeda , T. Takeshita , M. Talby , A. Talyshev ,M.C. Tamsett , J. Tanaka , R. Tanaka , S. Tanaka , S. Tanaka , S. Tapprogge , D. Tardif ,S. Tarem , F. Tarrade , G.F. Tartarelli , P. Tas , M. Tasevsky , E. Tassi , ,M. Tatarkhanov , C. Taylor , F.E. Taylor , G.N. Taylor , R.P. Taylor , W. Taylor ,P. Teixeira-Dias , H. Ten Kate , P.K. Teng , Y.D. Tennenbaum-Katan , S. Terada , K. Terashi ,J. Terron , M. Terwort , v , M. Testa , R.J. Teuscher , j , J. Therhaag , M. Thioye , S. Thoma ,J.P. Thomas , E.N. Thompson , P.D. Thompson , P.D. Thompson , R.J. Thompson ,A.S. Thompson , E. Thomson , R.P. Thun , T. Tic , V.O. Tikhomirov , Y.A. Tikhonov ,P. Tipton , F.J. Tique Aires Viegas , S. Tisserant , B. Toczek , T. Todorov , S. Todorova-Nova ,B. Toggerson , J. Tojo , S. Tok´ar , K. Tokushuku , K. Tollefson , L. Tomasek ,M. Tomasek , M. Tomoto , L. Tompkins , K. Toms , A. Tonoyan , C. Topfel , N.D. Topilin ,I. Torchiani , E. Torrence , E. Torr´o Pastor , J. Toth , ah , F. Touchard , D.R. Tovey ,T. Trefzger , L. Tremblet , A. Tricoli , I.M. Trigger , S. Trincaz-Duvoid , T.N. Trinh ,M.F. Tripiana , N. Triplett , W. Trischuk , A. Trivedi , an , B. Trocm´e , C. Troncon ,A. Trzupek , C. Tsarouchas , J.C-L. Tseng , M. Tsiakiris , P.V. Tsiareshka , D. Tsionou ,G. Tsipolitis , V. Tsiskaridze , E.G. Tskhadadze , I.I. Tsukerman , V. Tsulaia , J.-W. Tsung ,S. Tsuno , D. Tsybychev , J.M. Tuggle , C.D. Tunnell , D. Turecek , I. Turk Cakir ,E. Turlay , P.M. Tuts , M.S. Twomey , M. Tylmad , , M. Tyndel , K. Uchida , I. Ueda ,R. Ueno , M. Ugland , M. Uhlenbrock , M. Uhrmacher , F. Ukegawa , G. Unal , A. Undrus ,G. Unel , Y. Unno , D. Urbaniec , E. Urkovsky , P. Urquijo , ao , P. Urrejola , G. Usai ,M. Uslenghi , , L. Vacavant , V. Vacek , B. Vachon , S. Vahsen , P. Valente ,S. Valentinetti , , A. Valero , S. Valkar , E. Valladolid Gallego , S. Vallecorsa ,J.A. Valls Ferrer , R. Van Berg , H. van der Graaf , E. van der Kraaij , E. van der Poel ,D. van der Ster , N. van Eldik , P. van Gemmeren , Z. van Kesteren , I. van Vulpen ,W. Vandelli , A. Vaniachine , P. Vankov , F. Vannucci , R. Vari , E.W. Varnes , D. Varouchas ,A. Vartapetian , K.E. Varvell , L. Vasilyeva , V.I. Vassilakopoulos , F. Vazeille , C. Vellidis ,F. Veloso , S. Veneziano , A. Ventura , , D. Ventura , M. Venturi , N. Venturi ,V. Vercesi , M. Verducci , W. Verkerke , J.C. Vermeulen , M.C. Vetterli , f , I. Vichou ,T. Vickey , ap , G.H.A. Viehhauser , M. Villa , , E.G. Villani , M. Villaplana Perez ,E. Vilucchi , M.G. Vincter , E. Vinek , V.B. Vinogradov , S. Viret , J. Virzi , A. Vitale , ,O. Vitells , I. Vivarelli , F. Vives Vaque , S. Vlachos , M. Vlasak , N. Vlasov , A. Vogel ,P. Vokac , M. Volpi , H. von der Schmitt , J. von Loeben , H. von Radziewski , E. von Toerne ,V. Vorobel , V. Vorwerk , M. Vos , R. Voss , T.T. Voss , J.H. Vossebeld , N. Vranjes ,M. Vranjes Milosavljevic , V. Vrba , M. Vreeswijk , T. Vu Anh , D. Vudragovic ,R. Vuillermet , I. Vukotic , P. Wagner , J. Walbersloh , J. Walder , R. Walker ,W. Walkowiak , R. Wall , C. Wang , H. Wang , J. Wang , S.M. Wang , A. Warburton ,C.P. Ward , M. Warsinsky , R. Wastie , P.M. Watkins , A.T. Watson , M.F. Watson ,G. Watts , S. Watts , A.T. Waugh , B.M. Waugh , M.D. Weber , M. Weber , M.S. Weber ,P. Weber , A.R. Weidberg , J. Weingarten , C. Weiser , H. Wellenstein , P.S. Wells ,T. Wenaus , S. Wendler , Z. Weng , aq , T. Wengler , S. Wenig , N. Wermes , M. Werner ,P. Werner , M. Werth , U. Werthenbach , M. Wessels , K. Whalen , A. White , M.J. White ,S. White , S.R. Whitehead , D. Whiteson , D. Whittington , F. Wicek , D. Wicke ,eadiness of the ATLAS Tile Calorimeter for LHC collisions 57F.J. Wickens , W. Wiedenmann , M. Wielers , P. Wienemann , C. Wiglesworth ,L.A.M. Wiik , A. Wildauer , M.A. Wildt , v , H.G. Wilkens , E. Williams , H.H. Williams ,S. Willocq , J.A. Wilson , M.G. Wilson , A. Wilson , I. Wingerter-Seez , F. Winklmeier ,M. Wittgen , M.W. Wolter , H. Wolters , g , B.K. Wosiek , J. Wotschack , M.J. Woudstra ,K. Wraight , C. Wright , D. Wright , B. Wrona , S.L. Wu , X. Wu , E. Wulf , B.M. Wynne ,L. Xaplanteris , S. Xella , S. Xie , D. Xu , N. Xu , M. Yamada , A. Yamamoto ,K. Yamamoto , S. Yamamoto , T. Yamamura , J. Yamaoka , T. Yamazaki , Y. Yamazaki ,Z. Yan , H. Yang , U.K. Yang , Z. Yang , , W-M. Yao , Y. Yao , Y. Yasu , J. Ye , S. Ye ,M. Yilmaz , R. Yoosoofmiya , K. Yorita , R. Yoshida , C. Young , S.P. Youssef , D. Yu ,J. Yu , L. Yuan , A. Yurkewicz , R. Zaidan , A.M. Zaitsev , Z. Zajacova , V. Zambrano ,L. Zanello , , A. Zaytsev , C. Zeitnitz , M. Zeller , A. Zemla , C. Zendler , O. Zenin ,T. Zenis , Z. Zenonos , , S. Zenz , D. Zerwas , G. Zevi della Porta , Z. Zhan ,H. Zhang , J. Zhang , Q. Zhang , X. Zhang , L. Zhao , T. Zhao , Z. Zhao , A. Zhemchugov ,J. Zhong , ar , B. Zhou , N. Zhou , Y. Zhou , C.G. Zhu , H. Zhu , Y. Zhu , X. Zhuang ,V. Zhuravlov , R. Zimmermann , S. Zimmermann , S. Zimmermann , M. Ziolkowski ,L. ˇZivkovi´c , G. Zobernig , A. Zoccoli , , M. zur Nedden , V. Zutshi . University at Albany, 1400 Washington Ave, Albany, NY 12222, United States of America University of Alberta, Department of Physics, Centre for Particle Physics, Edmonton, AB T6G 2G7,Canada Ankara University ( a ) , Faculty of Sciences, Department of Physics, TR 061000 Tandogan, Ankara;Dumlupinar University ( b ) , Faculty of Arts and Sciences, Department of Physics, Kutahya; GaziUniversity ( c ) , Faculty of Arts and Sciences, Department of Physics, 06500, Teknikokullar, Ankara;TOBB University of Economics and Technology ( d ) , Faculty of Arts and Sciences, Division of Physics,06560, Sogutozu, Ankara; Turkish Atomic Energy Authority ( e ) , 06530, Lodumlu, Ankara, Turkey LAPP, Universit´e de Savoie, CNRS/IN2P3, Annecy-le-Vieux, France Argonne National Laboratory, High Energy Physics Division, 9700 S. Cass Avenue, Argonne IL60439, United States of America University of Arizona, Department of Physics, Tucson, AZ 85721, United States of America The University of Texas at Arlington, Department of Physics, Box 19059, Arlington, TX 76019,United States of America University of Athens, Nuclear & Particle Physics, Department of Physics, Panepistimiopouli,Zografou, GR 15771 Athens, Greece National Technical University of Athens, Physics Department, 9-Iroon Polytechniou, GR 15780Zografou, Greece Institute of Physics, Azerbaijan Academy of Sciences, H. Javid Avenue 33, AZ 143 Baku, Azerbaijan Institut de F´ısica d’Altes Energies, IFAE, Edifici Cn, Universitat Aut`onoma de Barcelona, ES -08193 Bellaterra (Barcelona), Spain University of Belgrade ( a ) , Institute of Physics, P.O. Box 57, 11001 Belgrade; Vinca Institute ofNuclear Sciences ( b ) M. Petrovica Alasa 12-14, 11000 Belgrade, Serbia, Serbia University of Bergen, Department for Physics and Technology, Allegaten 55, NO - 5007 Bergen,Norway Lawrence Berkeley National Laboratory and University of California, Physics Division,MS50B-6227, 1 Cyclotron Road, Berkeley, CA 94720, United States of America Humboldt University, Institute of Physics, Berlin, Newtonstr. 15, D-12489 Berlin, Germany University of Bern, Albert Einstein Center for Fundamental Physics, Laboratory for High EnergyPhysics, Sidlerstrasse 5, CH - 3012 Bern, Switzerland University of Birmingham, School of Physics and Astronomy, Edgbaston, Birmingham B15 2TT,United Kingdom Bogazici University ( a ) , Faculty of Sciences, Department of Physics, TR - 80815 Bebek-Istanbul;8 The ATLAS CollaborationDogus University ( b ) , Faculty of Arts and Sciences, Department of Physics, 34722, Kadikoy, Istanbul; ( c ) Gaziantep University, Faculty of Engineering, Department of Physics Engineering, 27310,Sehitkamil, Gaziantep, Turkey; Istanbul Technical University ( d ) , Faculty of Arts and Sciences,Department of Physics, 34469, Maslak, Istanbul, Turkey INFN Sezione di Bologna ( a ) ; Universit`a di Bologna, Dipartimento di Fisica ( b ) , viale C. Berti Pichat,6/2, IT - 40127 Bologna, Italy University of Bonn, Physikalisches Institut, Nussallee 12, D - 53115 Bonn, Germany Boston University, Department of Physics, 590 Commonwealth Avenue, Boston, MA 02215, UnitedStates of America Brandeis University, Department of Physics, MS057, 415 South Street, Waltham, MA 02454, UnitedStates of America Universidade Federal do Rio De Janeiro, COPPE/EE/IF ( a ) , Caixa Postal 68528, Ilha do Fundao, BR- 21945-970 Rio de Janeiro; ( b ) Universidade de Sao Paulo, Instituto de Fisica, R.do Matao Trav. R.187,Sao Paulo - SP, 05508 - 900, Brazil Brookhaven National Laboratory, Physics Department, Bldg. 510A, Upton, NY 11973, United Statesof America National Institute of Physics and Nuclear Engineering ( a ) , Bucharest-Magurele, Str. Atomistilor 407,P.O. Box MG-6, R-077125, Romania; University Politehnica Bucharest ( b ) , Rectorat - AN 001, 313Splaiul Independentei, sector 6, 060042 Bucuresti; West University ( c ) in Timisoara, Bd. Vasile Parvan4, Timisoara, Romania Universidad de Buenos Aires, FCEyN, Dto. Fisica, Pab I - C. Universitaria, 1428 Buenos Aires,Argentina University of Cambridge, Cavendish Laboratory, J J Thomson Avenue, Cambridge CB3 0HE, UnitedKingdom Carleton University, Department of Physics, 1125 Colonel By Drive, Ottawa ON K1S 5B6, Canada CERN, CH - 1211 Geneva 23, Switzerland University of Chicago, Enrico Fermi Institute, 5640 S. Ellis Avenue, Chicago, IL 60637, UnitedStates of America Pontificia Universidad Cat´olica de Chile, Facultad de Fisica, Departamento de Fisica ( a ) , Avda.Vicuna Mackenna 4860, San Joaquin, Santiago; Universidad T´ecnica Federico Santa Mar´ıa,Departamento de F´ısica ( b ) , Avda. Esp˜ana 1680, Casilla 110-V, Valpara´ıso, Chile Institute of High Energy Physics, Chinese Academy of Sciences ( a ) , P.O. Box 918, 19 Yuquan Road,Shijing Shan District, CN - Beijing 100049; University of Science & Technology of China (USTC),Department of Modern Physics ( b ) , Hefei, CN - Anhui 230026; Nanjing University, Department ofPhysics ( c ) , 22 Hankou Road, Nanjing, 210093; Shandong University, High Energy Physics Group ( d ) ,Jinan, CN - Shandong 250100, China Laboratoire de Physique Corpusculaire, Clermont Universit´e, Universit´e Blaise Pascal,CNRS/IN2P3, FR - 63177 Aubiere Cedex, France Columbia University, Nevis Laboratory, 136 So. Broadway, Irvington, NY 10533, United States ofAmerica University of Copenhagen, Niels Bohr Institute, Blegdamsvej 17, DK - 2100 Kobenhavn 0, Denmark INFN Gruppo Collegato di Cosenza ( a ) ; Universit`a della Calabria, Dipartimento di Fisica ( b ) , IT-87036Arcavacata di Rende, Italy Faculty of Physics and Applied Computer Science of the AGH-University of Science andTechnology, (FPACS, AGH-UST), al. Mickiewicza 30, PL-30059 Cracow, Poland The Henryk Niewodniczanski Institute of Nuclear Physics, Polish Academy of Sciences, ul.Radzikowskiego 152, PL - 31342 Krakow, Poland Southern Methodist University, Physics Department, 106 Fondren Science Building, Dallas, TX75275-0175, United States of America University of Texas at Dallas, 800 West Campbell Road, Richardson, TX 75080-3021, United Stateseadiness of the ATLAS Tile Calorimeter for LHC collisions 59of America DESY, Notkestr. 85, D-22603 Hamburg and Platanenallee 6, D-15738 Zeuthen, Germany TU Dortmund, Experimentelle Physik IV, DE - 44221 Dortmund, Germany Technical University Dresden, Institut f¨ur Kern- und Teilchenphysik, Zellescher Weg 19, D-01069Dresden, Germany Duke University, Department of Physics, Durham, NC 27708, United States of America University of Edinburgh, School of Physics & Astronomy, James Clerk Maxwell Building, TheKings Buildings, Mayfield Road, Edinburgh EH9 3JZ, United Kingdom Fachhochschule Wiener Neustadt; Johannes Gutenbergstrasse 3 AT - 2700 Wiener Neustadt, Austria INFN Laboratori Nazionali di Frascati, via Enrico Fermi 40, IT-00044 Frascati, Italy Albert-Ludwigs-Universit¨at, Fakult¨at f¨ur Mathematik und Physik, Hermann-Herder Str. 3, D - 79104Freiburg i.Br., Germany Universit´e de Gen`eve, Section de Physique, 24 rue Ernest Ansermet, CH - 1211 Geneve 4,Switzerland INFN Sezione di Genova ( a ) ; Universit`a di Genova, Dipartimento di Fisica ( b ) , via Dodecaneso 33, IT -16146 Genova, Italy Institute of Physics of the Georgian Academy of Sciences, 6 Tamarashvili St., GE - 380077 Tbilisi;Tbilisi State University, HEP Institute, University St. 9, GE - 380086 Tbilisi, Georgia Justus-Liebig-Universit¨at Giessen, II Physikalisches Institut, Heinrich-Buff Ring 16, D-35392Giessen, Germany University of Glasgow, Department of Physics and Astronomy, Glasgow G12 8QQ, United Kingdom Georg-August-Universit¨at, II. Physikalisches Institut, Friedrich-Hund Platz 1, D-37077 G¨ottingen,Germany Laboratoire de Physique Subatomique et de Cosmologie, CNRS/IN2P3, Universit´e Joseph Fourier,INPG, 53 avenue des Martyrs, FR - 38026 Grenoble Cedex, France Hampton University, Department of Physics, Hampton, VA 23668, United States of America Harvard University, Laboratory for Particle Physics and Cosmology, 18 Hammond Street,Cambridge, MA 02138, United States of America Ruprecht-Karls-Universit¨at Heidelberg: Kirchhoff-Institut f¨ur Physik ( a ) , Im Neuenheimer Feld 227,D-69120 Heidelberg; Physikalisches Institut ( b ) , Philosophenweg 12, D-69120 Heidelberg; ZITIRuprecht-Karls-University Heidelberg ( c ) , Lehrstuhl f¨ur Informatik V, B6, 23-29, DE - 68131Mannheim, Germany Hiroshima University, Faculty of Science, 1-3-1 Kagamiyama, Higashihiroshima-shi, JP - Hiroshima739-8526, Japan Hiroshima Institute of Technology, Faculty of Applied Information Science, 2-1-1 Miyake Saeki-ku,Hiroshima-shi, JP - Hiroshima 731-5193, Japan Indiana University, Department of Physics, Swain Hall West 117, Bloomington, IN 47405-7105,United States of America Institut f¨ur Astro- und Teilchenphysik, Technikerstrasse 25, A - 6020 Innsbruck, Austria University of Iowa, 203 Van Allen Hall, Iowa City, IA 52242-1479, United States of America Iowa State University, Department of Physics and Astronomy, Ames High Energy Physics Group,Ames, IA 50011-3160, United States of America Joint Institute for Nuclear Research, JINR Dubna, RU - 141 980 Moscow Region, Russia KEK, High Energy Accelerator Research Organization, 1-1 Oho, Tsukuba-shi, Ibaraki-ken 305-0801,Japan Kobe University, Graduate School of Science, 1-1 Rokkodai-cho, Nada-ku, JP Kobe 657-8501, Japan Kyoto University, Faculty of Science, Oiwake-cho, Kitashirakawa, Sakyou-ku, Kyoto-shi, JP - Kyoto606-8502, Japan Kyoto University of Education, 1 Fukakusa, Fujimori, fushimi-ku, Kyoto-shi, JP - Kyoto 612-8522,Japan0 The ATLAS Collaboration Universidad Nacional de La Plata, FCE, Departamento de F´ısica, IFLP (CONICET-UNLP), C.C. 67,1900 La Plata, Argentina Lancaster University, Physics Department, Lancaster LA1 4YB, United Kingdom INFN Sezione di Lecce ( a ) ; Universit`a del Salento, Dipartimento di Fisica ( b ) Via Arnesano IT - 73100Lecce, Italy University of Liverpool, Oliver Lodge Laboratory, P.O. Box 147, Oxford Street, Liverpool L69 3BX,United Kingdom Joˇzef Stefan Institute and University of Ljubljana, Department of Physics, SI-1000 Ljubljana,Slovenia Queen Mary University of London, Department of Physics, Mile End Road, London E1 4NS, UnitedKingdom Royal Holloway, University of London, Department of Physics, Egham Hill, Egham, Surrey TW200EX, United Kingdom University College London, Department of Physics and Astronomy, Gower Street, London WC1E6BT, United Kingdom Laboratoire de Physique Nucl´eaire et de Hautes Energies, Universit´e Pierre et Marie Curie (Paris 6),Universit´e Denis Diderot (Paris-7), CNRS/IN2P3, Tour 33, 4 place Jussieu, FR - 75252 Paris Cedex 05,France Lunds universitet, Naturvetenskapliga fakulteten, Fysiska institutionen, Box 118, SE - 221 00 Lund,Sweden Universidad Autonoma de Madrid, Facultad de Ciencias, Departamento de Fisica Teorica, ES -28049 Madrid, Spain Universit¨at Mainz, Institut f¨ur Physik, Staudinger Weg 7, DE - 55099 Mainz, Germany University of Manchester, School of Physics and Astronomy, Manchester M13 9PL, United Kingdom CPPM, Aix-Marseille Universit´e, CNRS/IN2P3, Marseille, France University of Massachusetts, Department of Physics, 710 North Pleasant Street, Amherst, MA01003, United States of America McGill University, High Energy Physics Group, 3600 University Street, Montreal, Quebec H3A 2T8,Canada University of Melbourne, School of Physics, AU - Parkville, Victoria 3010, Australia The University of Michigan, Department of Physics, 2477 Randall Laboratory, 500 East University,Ann Arbor, MI 48109-1120, United States of America Michigan State University, Department of Physics and Astronomy, High Energy Physics Group, EastLansing, MI 48824-2320, United States of America INFN Sezione di Milano ( a ) ; Universit`a di Milano, Dipartimento di Fisica ( b ) , via Celoria 16, IT -20133 Milano, Italy B.I. Stepanov Institute of Physics, National Academy of Sciences of Belarus, Independence Avenue68, Minsk 220072, Republic of Belarus National Scientific & Educational Centre for Particle & High Energy Physics, NC PHEP BSU, M.Bogdanovich St. 153, Minsk 220040, Republic of Belarus Massachusetts Institute of Technology, Department of Physics, Room 24-516, Cambridge, MA02139, United States of America University of Montreal, Group of Particle Physics, C.P. 6128, Succursale Centre-Ville, Montreal,Quebec, H3C 3J7 , Canada P.N. Lebedev Institute of Physics, Academy of Sciences, Leninsky pr. 53, RU - 117 924 Moscow,Russia Institute for Theoretical and Experimental Physics (ITEP), B. Cheremushkinskaya ul. 25, RU 117218 Moscow, Russia Moscow Engineering & Physics Institute (MEPhI), Kashirskoe Shosse 31, RU - 115409 Moscow,Russiaeadiness of the ATLAS Tile Calorimeter for LHC collisions 61 Lomonosov Moscow State University Skobeltsyn Institute of Nuclear Physics (MSU SINP), 1(2),Leninskie gory, GSP-1, Moscow 119991 Russian Federation, Russia Ludwig-Maximilians-Universit¨at M¨unchen, Fakult¨at f¨ur Physik, Am Coulombwall 1, DE - 85748Garching, Germany Max-Planck-Institut f¨ur Physik, (Werner-Heisenberg-Institut), F¨ohringer Ring 6, 80805 M¨unchen,Germany
Nagasaki Institute of Applied Science, 536 Aba-machi, JP Nagasaki 851-0193, Japan
Nagoya University, Graduate School of Science, Furo-Cho, Chikusa-ku, Nagoya, 464-8602, Japan
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Radboud University Nijmegen/NIKHEF, Department of Experimental High Energy Physics,Heyendaalseweg 135, NL-6525 AJ, Nijmegen, Netherlands
Nikhef National Institute for Subatomic Physics, and University of Amsterdam, Science Park 105,1098 XG Amsterdam, Netherlands
Department of Physics, Northern Illinois University, LaTourette Hall Normal Road, DeKalb, IL60115, United States of America
Budker Institute of Nuclear Physics (BINP), RU - Novosibirsk 630 090, Russia
New York University, Department of Physics, 4 Washington Place, New York NY 10003, USA,United States of America
Ohio State University, 191 West Woodruff Ave, Columbus, OH 43210-1117, United States ofAmerica
Okayama University, Faculty of Science, Tsushimanaka 3-1-1, Okayama 700-8530, Japan
University of Oklahoma, Homer L. Dodge Department of Physics and Astronomy, 440 WestBrooks, Room 100, Norman, OK 73019-0225, United States of America
Oklahoma State University, Department of Physics, 145 Physical Sciences Building, Stillwater, OK74078-3072, United States of America
Palack´y University, 17.listopadu 50a, 772 07 Olomouc, Czech Republic
University of Oregon, Center for High Energy Physics, Eugene, OR 97403-1274, United States ofAmerica
LAL, Univ. Paris-Sud, IN2P3/CNRS, Orsay, France
Osaka University, Graduate School of Science, Machikaneyama-machi 1-1, Toyonaka, Osaka560-0043, Japan
University of Oslo, Department of Physics, P.O. Box 1048, Blindern, NO - 0316 Oslo 3, Norway
Oxford University, Department of Physics, Denys Wilkinson Building, Keble Road, Oxford OX13RH, United Kingdom
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Petersburg Nuclear Physics Institute, RU - 188 300 Gatchina, Russia
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Laboratorio de Instrumentacao e Fisica Experimental de Particulas - LIP ( a ) , Avenida Elias Garcia14-1, PT - 1000-149 Lisboa, Portugal; Universidad de Granada, Departamento de Fisica Teorica y delCosmos and CAFPE ( b ) , E-18071 Granada, Spain Institute of Physics, Academy of Sciences of the Czech Republic, Na Slovance 2, CZ - 18221 Praha2 The ATLAS Collaboration8, Czech Republic
Charles University in Prague, Faculty of Mathematics and Physics, Institute of Particle and NuclearPhysics, V Holesovickach 2, CZ - 18000 Praha 8, Czech Republic
Czech Technical University in Prague, Zikova 4, CZ - 166 35 Praha 6, Czech Republic
State Research Center Institute for High Energy Physics, Moscow Region, 142281, Protvino,Pobeda street, 1, Russia
Rutherford Appleton Laboratory, Science and Technology Facilities Council, Harwell Science andInnovation Campus, Didcot OX11 0QX, United Kingdom
University of Regina, Physics Department, Canada
Ritsumeikan University, Noji Higashi 1 chome 1-1, JP - Kusatsu, Shiga 525-8577, Japan
INFN Sezione di Roma I ( a ) ; Universit`a La Sapienza, Dipartimento di Fisica ( b ) , Piazzale A. Moro 2,IT- 00185 Roma, Italy INFN Sezione di Roma Tor Vergata ( a ) ; Universit`a di Roma Tor Vergata, Dipartimento di Fisica ( b ) ,via della Ricerca Scientifica, IT-00133 Roma, Italy INFN Sezione di Roma Tre ( a ) ; Universit`a Roma Tre, Dipartimento di Fisica ( b ) , via della VascaNavale 84, IT-00146 Roma, Italy R´eseau Universitaire de Physique des Hautes Energies (RUPHE): Universit´e Hassan II, Facult´e desSciences Ain Chock ( a ) , B.P. 5366, MA - Casablanca; Centre National de l’Energie des SciencesTechniques Nucleaires (CNESTEN) ( b ) , B.P. 1382 R.P. 10001 Rabat 10001; Universit´e MohamedPremier ( c ) , LPTPM, Facult´e des Sciences, B.P.717. Bd. Mohamed VI, 60000, Oujda ; Universit´eMohammed V, Facult´e des Sciences ( d ) CEA, DSM/IRFU, Centre d’Etudes de Saclay, FR - 91191 Gif-sur-Yvette, France
University of California Santa Cruz, Santa Cruz Institute for Particle Physics (SCIPP), Santa Cruz,CA 95064, United States of America
University of Washington, Seattle, Department of Physics, Box 351560, Seattle, WA 98195-1560,United States of America
University of Sheffield, Department of Physics & Astronomy, Hounsfield Road, Sheffield S3 7RH,United Kingdom
Shinshu University, Department of Physics, Faculty of Science, 3-1-1 Asahi, Matsumoto-shi, JP -Nagano 390-8621, Japan
Universit¨at Siegen, Fachbereich Physik, D 57068 Siegen, Germany
Simon Fraser University, Department of Physics, 8888 University Drive, CA - Burnaby, BC V5A1S6, Canada
SLAC National Accelerator Laboratory, Stanford, California 94309, United States of America
Comenius University, Faculty of Mathematics, Physics & Informatics ( a ) , Mlynska dolina F2, SK -84248 Bratislava; Institute of Experimental Physics of the Slovak Academy of Sciences, Dept. ofSubnuclear Physics ( b ) , Watsonova 47, SK - 04353 Kosice, Slovak Republic ( a ) University of Johannesburg, Department of Physics, PO Box 524, Auckland Park, Johannesburg2006; ( b ) School of Physics, University of the Witwatersrand, Private Bag 3, Wits 2050, Johannesburg,South Africa, South Africa
Stockholm University: Department of Physics ( a ) ; The Oskar Klein Centre ( b ) , AlbaNova, SE - 10691 Stockholm, Sweden Royal Institute of Technology (KTH), Physics Department, SE - 106 91 Stockholm, Sweden
Stony Brook University, Department of Physics and Astronomy, Nicolls Road, Stony Brook, NY11794-3800, United States of America
University of Sussex, Department of Physics and Astronomy Pevensey 2 Building, Falmer, BrightonBN1 9QH, United Kingdom
University of Sydney, School of Physics, AU - Sydney NSW 2006, Australia
Insitute of Physics, Academia Sinica, TW - Taipei 11529, Taiwan
Technion, Israel Inst. of Technology, Department of Physics, Technion City, IL - Haifa 32000, Israeleadiness of the ATLAS Tile Calorimeter for LHC collisions 63
Tel Aviv University, Raymond and Beverly Sackler School of Physics and Astronomy, Ramat Aviv,IL - Tel Aviv 69978, Israel
Aristotle University of Thessaloniki, Faculty of Science, Department of Physics, Division ofNuclear & Particle Physics, University Campus, GR - 54124, Thessaloniki, Greece
The University of Tokyo, International Center for Elementary Particle Physics and Department ofPhysics, 7-3-1 Hongo, Bunkyo-ku, JP - Tokyo 113-0033, Japan
Tokyo Metropolitan University, Graduate School of Science and Technology, 1-1 Minami-Osawa,Hachioji, Tokyo 192-0397, Japan
Tokyo Institute of Technology, 2-12-1-H-34 O-Okayama, Meguro, Tokyo 152-8551, Japan
University of Toronto, Department of Physics, 60 Saint George Street, Toronto M5S 1A7, Ontario,Canada
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University of Tsukuba, Institute of Pure and Applied Sciences, 1-1-1 Tennoudai, Tsukuba-shi, JP -Ibaraki 305-8571, Japan
Tufts University, Science & Technology Center, 4 Colby Street, Medford, MA 02155, United Statesof America
Universidad Antonio Narino, Centro de Investigaciones, Cra 3 Este No.47A-15, Bogota, Colombia
University of California, Irvine, Department of Physics & Astronomy, CA 92697-4575, UnitedStates of America
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Instituto de F´ısica Corpuscular (IFIC) Centro Mixto UVEG-CSIC, Apdo. 22085 ES-46071Valencia, Dept. F´ısica At. Mol. y Nuclear; Dept. Ing. Electr´onica; Univ. of Valencia, and Inst. deMicroelectr´onica de Barcelona (IMB-CNM-CSIC) 08193 Bellaterra, Spain
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Yale University, Department of Physics, PO Box 208121, New Haven CT, 06520-8121, UnitedStates of America
Yerevan Physics Institute, Alikhanian Brothers Street 2, AM - 375036 Yerevan, Armenia
ATLAS-Canada Tier-1 Data Centre, TRIUMF, 4004 Wesbrook Mall, Vancouver, BC, V6T 2A3,Canada
GridKA Tier-1 FZK, Forschungszentrum Karlsruhe GmbH, Steinbuch Centre for Computing (SCC),Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
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Academia Sinica Grid Computing, Institute of Physics, Academia Sinica, No.128, Sec. 2, AcademiaRd., Nankang, Taipei, Taiwan 11529, Taiwan
UK-T1-RAL Tier-1, Rutherford Appleton Laboratory, Science and Technology Facilities Council,Harwell Science and Innovation Campus, Didcot OX11 0QX, United Kingdom
RHIC and ATLAS Computing Facility, Physics Department, Building 510, Brookhaven NationalLaboratory, Upton, New York 11973, United States of America a Also at LIP, Portugal b Also at Faculdade de Ciencias, Universidade de Lisboa, Portugal c Also at CPPM, Marseille, France. d Also at TRIUMF, Vancouver, Canada e Also at FPACS, AGH-UST, Cracow, Poland f Also at TRIUMF, Vancouver, Canada g Also at Department of Physics, University of Coimbra, Portugal h Now at CERN i Also at Universit`a di Napoli Parthenope, Napoli, Italy j Also at Institute of Particle Physics (IPP), Canada k Also at Universit`a di Napoli Parthenope, via A. Acton 38, IT - 80133 Napoli, Italy l Louisiana Tech University, 305 Wisteria Street, P.O. Box 3178, Ruston, LA 71272, United States ofAmerica m Also at Universidade de Lisboa, Portugal n At California State University, Fresno, USA o Also at TRIUMF, 4004 Wesbrook Mall, Vancouver, B.C. V6T 2A3, Canada p Currently at Istituto Universitario di Studi Superiori IUSS, Pavia, Italy q Also at Faculdade de Ciencias, Universidade de Lisboa, Portugal and at Centro de Fisica Nuclear daUniversidade de Lisboa, Portugal r Also at FPACS, AGH-UST, Cracow, Poland s Also at California Institute of Technology, Pasadena, USA t Louisiana Tech University, Ruston, USA u Also at University of Montreal, Montreal, Canada v Also at Institut f¨ur Experimentalphysik, Universit¨at Hamburg, Hamburg, Germany w Also at Petersburg Nuclear Physics Institute, Gatchina, Russia x Also at Institut f¨ur Experimentalphysik, Universit¨at Hamburg, Luruper Chaussee 149, 22761Hamburg, Germany y Also at School of Physics and Engineering, Sun Yat-sen University, China z Also at School of Physics, Shandong University, Jinan, China aa Also at California Institute of Technology, Pasadena, USA ab Also at Rutherford Appleton Laboratory, Didcot, UK ac Also at school of physics, Shandong University, Jinan ad Also at Rutherford Appleton Laboratory, Didcot , UK ae Now at KEK a f
Also at Departamento de Fisica, Universidade de Minho, Portugal ag University of South Carolina, Columbia, USA ah Also at KFKI Research Institute for Particle and Nuclear Physics, Budapest, Hungary ai University of South Carolina, Dept. of Physics and Astronomy, 700 S. Main St, Columbia, SC 29208,eadiness of the ATLAS Tile Calorimeter for LHC collisions 65United States of America a j
Also at Institute of Physics, Jagiellonian University, Cracow, Poland ak Louisiana Tech University, Ruston, USA al Also at Centro de Fisica Nuclear da Universidade de Lisboa, Portugal am Also at School of Physics and Engineering, Sun Yat-sen University, Taiwan an University of South Carolina, Columbia, USA ao Transfer to LHCb 31.01.2010 ap Also at Department of Physics, Oxford University, Oxford, United Kingdom. aq Also at Sun Yat-sen University, Guangzhou, PR China ar Also at Nanjing University, China ∗∗