Performance and simulation of the T1 detectors

1. Performance and simulation of the T1 detectors TOTEM plenary meeting CERN 15-16 February 2005 Fabrizio Ferro

2. 2003 and 2004 test beams • The goals of two years of tests were • Measure CSC performances (gain, space resolution, time resolution) • Measure telescope performances (trigger, track reconstruction) • Test electronics and DAQ • Test hardware reliability Fabrizio Ferro

3. CSC T1 60° • 2 planes of 192 cathode strips • 30 mm goldplated anode wires with 3mm pitch • Measurement 3 coordinates Fabrizio Ferro

4. CSC test setup 2003 9x9cm scint 9x9cm scint 2004 4 trapezoidal prototypes for 2004 tests. Simulation of (almost) a T1 sextant. Fabrizio Ferro

5. 2004 BEAM Fabrizio Ferro

6. 2003 electronics and DAQ • Cathode readout with Gassiplex ( ~700ns peaking time). Signal multiplexed in a VME bus and converted by a 12 bit flash-ADC. • Anode readout with CMS AFEB (amplifier, shaper, discriminator with adjustable threshold). Time arrival measured with a multi-hit TDC. Read-out area Fabrizio Ferro

7. 2003 online monitor • Data quality checked on line • Two different monitor windows for strips and wires • Automatic pedestal subtraction CSC cathodes monitor 3s Fabrizio Ferro

8. 2004 electronics • Cathode electronics • 8 FrontEndCards + 1 R/O ControlUnit • FEC (TPC-ALICE) equipped with chip ALTRO • ALTRO: signal sampled at 20MHz with a 10 bit flash-ADC • Data acquisition with DATE • Anode electronics • 8 AFEBs and a (CMS) ALCT • ALCT allows threshold setup, fast trigger generation and data acquisition through CMS trigger mother board. Fabrizio Ferro

9. Test results: CSC construction • Very good behavior of all prototypes: no gas leakage and HV working point reached. • Experience: time for construction as declared in TDR. Fabrizio Ferro

10. DATA storage and format • Collected more than 1 million events stored in castor storage facility /castor/cern.ch/totem/rawdata/CSC2003 /castor/cern.ch/totem/rawdata/CSC2004 • Note: different data format due to different acquisition chain • Ex: 2004 – ALTRO data packing F-ADC data into 10 bit words packed in a 40 bit architecture… Fabrizio Ferro

11. DATA analysis: cluster reconstruction • Cluster reconstruction implemented in the offline software • Position measured with charge sharing Two reco. clusters Charge measurement Gain Fabrizio Ferro

12. Gain measurement (find and fatt: induction and attenuation factors a) • Gain measurement allows equalization among different CSC • Gain grows up exponentially with HV (a: electr. Calibration) a values of parameters from CMS Fabrizio Ferro

13. Working point • Working point determination: high efficiency on both anodes and cathodes, high S/N ratio, reliability Anode efficiency Cathode efficiency plateau WP candidate Cathode efficiency Fabrizio Ferro

14. Track reconstruction and spatial resolution • Software detector alignment • Track reconstruction fitting u and v coordinates with straight lines • Spatial resolution measured reconstructing tracks with 3/4 detectors u residuals su~sv = 0.44 mm sx = 0.36 mm sy = 0.62 mm Required precision in vertexing Fabrizio Ferro

15. Trigger and timing • T1 trigger generated by combination of anode signals • Measurement of timing of anode signals (with TDC) • T1 bunch crossing identification compatible with 1 bunch over 3 (75 ns spacing), with a 3/4 planes pattern 2^ signal in coincidence Single wire time distribution Fabrizio Ferro

16. Trigger tests • T1 self triggering successfully tested • Pattern: 3/4 aligned wires (testbeam CSCs not rotated wrt each other) • Data acquired both with external scintillator and with internal wire trigger • Time distribution of peaks of cathode signals show compatibility with previous timing measurements Time distribution of peaks Fabrizio Ferro

17. Trigger simulation An update from T1 software trigger simulation • A root compatible code implemented with description of CSC segmentation (T1.so shared library loadable by root) • Very preliminary trigger pattern implemented (detailed studies in progress) • Looking for straight line roads • Starting from a hit wire in the (say) 1st plane, a hit wire in the 2nd is looked for in the hypothesis of a straight track coming from IP • A tolerance of n (±8 ?) wires needed because of rotation between adjacent planes • Adjacent sextants are considered as well, to guarantee telescope hermeticity PRELIMINARY Fabrizio Ferro

18. Some results on T1 • Rates similar to those published in TDR T1 one arm efficiency PRELIMINARY (without adjacent sextants) Fabrizio Ferro

19. p Beam gas background • Beam gas events generated in 11 different regions of the beampipe (±15, ±10, ±5, ±3, ±1, 0m from the IP). Percentage of BG events which pass T1 trigger selection PRELIMINARY • Rates similar to TDR • Poor pointing power of the preliminary trigger pattern used. • Beamgas rejection needs vertex (not at LVL1) and/or more pointing trigger • Deeper studies in progress  enhance pointing power saving efficiency Fabrizio Ferro

20. Conclusions • T1 CSCs were extensively tested in the last 2 test beams • Measurements to characterize the detector performances, DAQ, electronics and trigger: we learnt a lot; detector behavior and timescale for construction as declared in the TDR • Self-triggerability of T1 successfully tested • Tests of the telescope with cosmic rays have been set up in Genoa • T1 simulation is working. Internal detector segmentation implemented outside CMS-ORCA • Trigger patterns implemented in the simulation. More extensive and detailed studies in progress. Fabrizio Ferro

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