Summary of One Year Operation of the EUDET CMOS Pixel Telescope
aa r X i v : . [ phy s i c s . i n s - d e t ] J a n Summary of One Year Operation of the EUDETCMOS Pixel Telescope
Ingrid-Maria Gregor ∗
1- DESY Hamburg, Notkestr. 85, D-22607 Hamburg, GermanyWithin the EUDET consortium a high resolution pixel beam telescope is being devel-oped. The telescope consists of up to six planes of monolithic active pixel sensors. Aflexible data acquisition environment is available for the telescope and the system isequipped with all the required infrastructure. Since the first installation of a demon-strator telescope in 2007, it has been extensively tested and used by various detectorR&D groups. The results of test beam measurements are described here, demonstratingthe telescope performance.
Figure 1: The EUDET pixel telescope installed atthe CERN hadron test beam.The EUDET project [2], which is sup-ported by the EU in the 6th Frame-work Programme (FP6), aims to pro-vide infrastructure for the R&D of de-tector technologies towards the interna-tional linear collider. Within the EU-DET project the JRA1 activity workson the improvement of test beam in-frastructure. For this purpose, a highresolution pixel telescope is being de-veloped. The design goals include ahigh position resolution ( σ < . µ m)and readout rate of 1 kHz.The construction of the telescopeis performed in two steps. In June2007, the so-called demonstrator tele-scope was installed for the first time using an analog readout. After the first successfuloperation at the electron beam at DESY, the demonstrator was transported to CERN andits performance was studied using 180 GeV hadrons at the SPS [3]. After the first successfulintegration of a Device Under Test (DUT) in September 2007 [4], the demonstrator telescopehas been used by various groups and was improved continuously. The MimoTEL sensor, used for the demonstrator telescope, is a Monolithic Active PixelSensor (MAPS) produced in the AMS 0.35 OPTO process. It is subdivided in four sub-arrays of 64 ×
256 pixels with a pixel pitch of 30 × µ m , resulting in a sensor size of ∗ This work is supported by the Commission of the European Communities under the 6 th FrameworkProgramme ¨Structering the European Research Area¨, contract number RII3-026126.
LCWS/ILC 2008 .7 × . A high resolution sensor with a pitch of 10 µ m can be located close to theDUT to further increase the resolution. The DAQ system can be summarised as follows: All data from the sensors is transferredvia frontend boards to an intermediate readout and data reduction board called EUDRB(EUDET Data Reduction Board) [5]. The EUDRB board allows the first steps of the dataprocessing online to be performed. Two I/O busses are supported: For the telescope theVME64x bus is used to allow high speed data transfer and synchronous operation with otherdevices while an USB2.0 interface is foreseen for standalone testing. A mother / daughterboard scheme has been followed to maximise the flexibility. All computing and memoryelements are located on the motherboard while the sensor specific components have beenimplemented on removable and interchangeable daughter cards.Another important component of the DAQ system is the trigger logic unit (TLU) [7].It is considered as the replacement for a NIM crate and can generate any coincidence oranticoincidence of four trigger scintillators. Six LVDS and two TTL interfaces are provided.Furthermore, the TLU generates event numbers and time stamps. It is connected by USB2.0to a control PC running the Linux operating system that is in turn connected to the mainDAQ PC through gigabit ethernet.A custom DAQ system named EUDAQ has been implemented in C++ [8]. Severalproducer tasks communicate with a global run control using sockets. These producer tasksconnect to the hardware of the beam telescope, to the TLU and eventually to the DUT.Data from all producers is sent to the central data collector and can be monitored by severalprocesses. An online monitor, based on the ROOT framework, shows online data qualitymonitoring histograms and a process to collect log messages is available. EUDAQ runs onMacOS, Linux and Windows using cygwin.
For the offline reconstruction of track positions in the DUT the software package EUTele-scope [9] has been developed, which is implemented as a set of Marlin processors [10]. Thisdesign allows to integrate the DUT data at different steps of the analysis chain. Furthermore,the package can be executed on the Grid to allow a fast processing of large datasets.
Figure 2 shows the residuals of the tracks in the middle out of 5 sensor planes. Here themiddle telescope sensor acts as DUT while the other planes are used to predict the trackpositions in the DUT. The observed width is consistent with the expectation for the giventelescope geometry assuming a position resolution of 3.0 µ m for the DUT as well as for theother sensors used to fit tracks. Also, measurements at DESY using 3 and 6 GeV electronsbased on an extrapolation to infinite energy are in agreement with this sensor resolution.The telescope was used by 7 different detector R&D groups for resolution studies of theirown systems. All of them were satisfied with the telescope performance and are planning touse it again in 2009. LCWS/ILC 2008 m µ −10 −5 0 5 10020040060080010001200 m µ ± = 3.3 σ m µ ± = −0.1 x m µ −10 −5 0 5 10020040060080010001200 m µ ± = 3.4 σ m µ ± = 0.0 y Figure 2: Residuals in the middle telescope sensor in the X (left) and Y (right) directions.This sensor was excluded from the track fit and hence acts as DUT. The data was recordedat the CERN SPS hadron test beam. The demonstrator telescope has been running successfully during several test beam mea-surements for about one year. Modularity was one of the most important design aspectsfor the DAQ hardware and software as well as for the offline analysis package. The analysisof test beam data shows that the performance of the demonstrator fulfils the expectations.An increased active area and zero suppression on the sensors will be offered by the finaltelescope which is under construction. Groups interested in using the device are welcome tocontact the EUDET consortium.
References [1] Presentation: http://ilcagenda.linearcollider.org/contributionDisplay.py?contribId=165&sessionId=21&confId=2628