C. E. Covault

First measurement of the total proton-proton cross-section at the LHC energy of \chem{\sqrt{s} = 7\,TeV}

TOTEM has measured the differential cross-section for elastic proton-proton scattering at the LHC energy of analysing data from a short run with dedicated large-β* optics. A single exponential fit with a slope B=(20.1±0.2stat±0.3syst) GeV−2 describes the range of the four-momentum transfer squared |t| from 0.02 to 0.33 GeV2. After the extrapolation to |t|=0, a total elastic scattering cross-section of (24.8±0.2stat±1.2syst) mb was obtained. Applying the optical theorem and using the luminosity measurement from CMS, a total proton-proton cross-section of (98.3±0.2stat±2.8syst) mb was deduced which is in good agreement with the expectation from the overall fit of previously measured data over a large range of center-of-mass energies. From the total and elastic pp cross-section measurements, an inelastic pp cross-section of was inferred.

Measurement of proton-proton elastic scattering and total cross-section at \chem{\sqrt {s} = 7\,TeV}

At the LHC energy of , under various beam and background conditions, luminosities, and Roman Pot positions, TOTEM has measured the differential cross-section for proton-proton elastic scattering as a function of the four-momentum transfer squared t. The results of the different analyses are in excellent agreement demonstrating no sizeable dependence on the beam conditions. Due to the very close approach of the Roman Pot detectors to the beam center (?5?beam) in a dedicated run with ?*?=?90?m, |t|-values down to 5?10?3?GeV2 were reached. The exponential slope of the differential elastic cross-section in this newly explored |t|-region remained unchanged and thus an exponential fit with only one constant B?=?(19.9???0.3)?GeV?2 over the large |t|-range from 0.005 to 0.2?GeV2 describes the differential distribution well. The high precision of the measurement and the large fit range lead to an error on the slope parameter B which is remarkably small compared to previous experiments. It allows a precise extrapolation over the non-visible cross-section (only 9%) to t?=?0. With the luminosity from CMS, the elastic cross-section was determined to be (25.4???1.1)?mb, and using in addition the optical theorem, the total pp cross-section was derived to be (98.6???2.2)?mb. For model comparisons the t-distributions are tabulated including the large |t|-range of the previous measurement (TOTEM Collaboration (Antchev G. et al), EPL, 95 (2011) 41001).

Proton-proton elastic scattering at the LHC energy of \chem{\sqrt{s} = 7\,TeV}

Proton-proton elastic scattering has been measured by the TOTEM experiment at the CERN Large Hadron Collider at √ s = 7 TeV in dedicated runs with the Roman Pot detectors placed as close as seven times the transverse beam size (σbeam) from the outgoing beams. After careful study of the accelerator optics and the detector alignment, |t|, the square of four-momentum transferred in the elastic scattering process, has been determined with an uncertainty of δt = 0.1 GeV p |t|. In this letter, first results of the differential cross-section are presented covering a |t|-range from 0.36 to 2.5 GeV 2 . The differential cross-section in the range 0.36 < |t| < 0.47 GeV 2 is described by an exponential with a slope parameter B =( 23.6 ± 0.5 stat ± 0.4 syst )G eV −2 , followed by a significant diffractive minimum at |t| =( 0.53 ± 0.01 stat ± 0.01 syst )G eV 2 .F or|t|-values larger than ∼ 1. 5G eV 2 , the cross-section exhibits a power law behaviour with an exponent of −7.8 ± 0.3 stat ± 0.1 syst . When compared to predictions based on the different available models, the data show a strong discriminative power despite the small t-range covered. open access Copyright c EPLA, 2011

Measurement of the Cosmic Ray Energy Spectrum and Composition from 10^{17} to 10^{18.3} eV Using a Hybrid Fluorescence Technique

We study the spectrum and average mass composition of cosmic rays with primary energies between 10^{17} eV and 10^{18} eV using a hybrid detector consisting of the High Resolution Flys Eye (HiRes) prototype and the MIA muon array. Measurements have been made of the change in the depth of shower maximum as a function of energy. A complete Monte Carlo simulation of the detector response and comparisons with shower simulations leads to the conclusion that the cosmic ray intensity is changing f rom a heavier to a lighter composition in this energy range. The spectrum is consistent with earlier Flys Eye measurements and supports the previously found steepening near 4 \times 10^{17} eV .

Measurement of the forward charged-particle pseudorapidity density in pp collisions at ?s = 7?TeV with the TOTEM experiment

The TOTEM experiment has measured the charged-particle pseudorapidity density dNch/d? in pp collisions at for 5.3<|?|<6.4 in events with at least one charged particle with transverse momentum above 40?MeV/c in this pseudorapidity range. This extends the analogous measurement performed by the other LHC experiments to the previously unexplored forward ? region. The measurement refers to more than 99% of non-diffractive processes and to single and double diffractive processes with diffractive masses above ~3.4?GeV/c2, corresponding to about 95% of the total inelastic cross-section. The dNch/d? has been found to decrease with |?|, from 3.84 ? 0.01(stat) ? 0.37(syst) at |?|=5.375 to 2.38?0.01(stat)?0.21(syst) at |?|=6.375. Several MC generators have been compared to data; none of them has been found to fully describe the measurement.

Observations of the BL Lacertae Object 3C 66A with STACEE

We present the analysis and results of recent high-energy gamma-ray observations of the BL Lac object 3C 66A conducted with the Solar Tower Atmospheric Cherenkov Effect Experiment (STACEE). During the 2003-2004 observing season, STACEE extensively observed 3C 66A as part of a multiwavelength campaign on the source. A total of 33.7 hours of data was taken on the source, plus an equivalent-duration background observation. After cleaning the data set a total of 16.3 hours of live time remained, and a net on-source excess of 1134 events was seen against a background of 231742 events. At a significance of 2.2 standard deviations this excess is insufficient to claim a detection of 3C 66A, but is used to establish flux upper limits for the source.

Measurement of proton-proton inelastic scattering cross-section at \chem{\sqrt {s} = 7\,{\mathrm {TeV}}}

The TOTEM experiment at the LHC has measured the inelastic proton-proton cross-section at in a ?*?=?90?m run with low inelastic pile-up. The measurement was based on events with at least one charged particle in the T2 telescope acceptance of 5.3?<?|?|?<?6.5 in pseudorapidity. Combined with data from the T1 telescope, covering 3.1?<?|?|?<?4.7, the cross-section for inelastic events with at least one |?|???6.5 final-state particle was determined to be (70.5???2.9)?mb. This cross-section includes all central diffractive events of which maximally 0.25?mb is estimated to escape the detection of the telescopes. Based on models for low mass diffraction, the total inelastic cross-section was deduced to be (73.7???3.4)?mb. An upper limit of 6.31?mb at 95% confidence level on the cross-section for events with diffractive masses below 3.4?GeV was obtained from the difference between the overall inelastic cross-section obtained by TOTEM using elastic scattering and the cross-section for inelastic events with at least one |?|???6.5 final-state particle.

Elastic Scattering and Total Cross-Section in p+p Reactions As Measured by the LHC Experiment TOTEM at √ s =7 TeV

Tamas Csorgő4 for the TOTEM Collaboration: G. Antchev,∗) P. Aspell,8 I. Atanassov,8,∗)V. Avati,8 J. Baechler,8 V. Berardi,5b,5a M. Berretti,7b E. Bossini,7b M. Bozzo,6b,6a P. Brogi,7b E. Brucken,3a,3b A. Buzzo,6a F. S. Cafagna,5a M. Calicchio,5b,5a M. G. Catanesi,5a C. Covault,9 M. Csanad,4,∗∗) M. Deile,8 E. Dimovasili,8 M. Doubek,1b K. Eggert,9 V. Eremin,∗∗∗) R. Ferretti,6a,6b F. Ferro,6a A. Fiergolski,†) F. Garcia,3a S. Giani,8 V. Greco,7b,8 L. Grzanka,8,††) J. Heino,3a T. Hilden,3a,3b M. R. Intonti,5a M. Janda,1b J. Kaspar,1a,8 J. Kopal,1a,8 V. Kundrat,1a K. Kurvinen,3a S. Lami,7a G. Latino,7b R. Lauhakangas,3a T. Leszko,† E. Lippmaa,2 M. Lokajicek,1a M. Lo Vetere,6b,6a F. Lucas Rodŕiguez,8 M. Macŕi,6a L. Magaletti,5b,5a G. Magazzu,7a A. Mercadante,5b,5a M. Meucci,7b S. Minutoli,6a F. Nemes,4,∗∗) H. Niewiadomski,8 E. Noschis,8 T. Novak,4,† † †) E. Oliveri,7b F. Oljemark,3a,3b R. Orava,3a,3b M. Oriunno,8,‡) K. Osterberg,3a,3b P. Palazzi,7b A.-L. Perrot,8 E. Pedreschi,7a J. Petajajarvi,3a J. Prochazka,1a M. Quinto,5a E. Radermacher,8 E. Radicioni,5a F. Ravotti,8 E. Robutti,6a L. Ropelewski,8 G. Ruggiero,8 H. Saarikko,3a,3b G. Sanguinetti,7a A. Santroni,6b,6a A. Scribano,7b G. Sette,6b,6a W. Snoeys,8 F. Spinella,7a J. Sziklai,4 C. Taylor,9 N. Turini,7b V. Vacek,1b M. Vitek,1b J. Welti,3a,b J. Whitmore10

A search for ultra{endash}high-energy gamma-ray emission from the Crab Nebula and Pulsar

We have examined 2.4 × 109 events recorded by the Chicago Air Shower Array-Michigan Muon Array (CASA-MIA) experiment for evidence of ultra-high-energy (100 TeV) neutral particle and gamma-ray emissions from the Crab Nebula and Pulsar between 1990 March 4 and 1995 October 9. No such emissions have been detected. Over this interval, the 90% confidence level integral flux limits for continuous emission above 141 TeV are 2.08 × 10-14 cm-2 s-1 for any neutral particle (which can produce a detectable air shower) and 9.21 × 10-15 cm-2 s-1 for gamma rays. There is no evidence of transient emission on timescales of 1 day or longer. The 90% confidence level integral flux limit for emission on a single day is conservatively estimated to be 4.40 × 10-12 cm-2 s-1 for any neutral particle and 5.09 × 10-12 cm-2 s-1 for gamma rays. There is no evidence for emission from the pulsar at the radio period on intervals of 1 day or longer. The 2 σ (97.7% confidence) limit on the pulsed flux on the most significant day is 3.29 × 10-12 cm-2 s-1 for any neutral particle with mass less than 21 MeV, and 8.31 × 10-12 cm-2 s-1 for gamma rays. For an interval of 162 sidereal days beginning 1992 March 1, the pulsed flux limit was 2.39 × 10-13 cm-2 s-1 for any neutral particle with mass less than 21 MeV, again above 141 TeV.

OSETI with STACEE: a search for nanosecond optical transients from nearby stars.

We have used the Solar Tower Atmospheric Cherenkov Effect Experiment (STACEE) high-energy gamma-ray detector to look for fast blue-green laser pulses from the vicinity of 187 stars. The STACEE detector offers unprecedented light-collecting capability for the detection of nanosecond pulses from such lasers. We estimate STACEEs sensitivity to be approximately 10 photons/m(2) at a wavelength of 420 nm. The stars have been chosen because their characteristics are such that they may harbor habitable planets, and they are relatively close to Earth. Each star was observed for 10 minutes, and we found no evidence for laser pulses in any of the data sets. Key Words: Search for extraterrestrial intelligence-Optical search for extraterrestrial intelligence-Interstellar communication-Laser.