Mariana Petris, NIPNE Bucharest CBM Meeting, March 9 -12, 2005 HIGH COUNTING RATE TRANSITION RADIATION DETECTOR Bucharest Prototype In Beam Tests

Transition Radiation Detectors ALICE - TRD ATLAS - TRT - type (radiator+drift chamber + MWPC) (radiator + straw tubes) -  rej (at 90% e efficiency) Maximum drift time 2  s 40 ns - Counting rates ~ 100 Hz/cm 2 ~ 1MHz/ cm 2 - Granularity (channel size) high (~6 cm 2 ) low (~20cm 2 ) CBM - TRD Counting rates ~ 100 KHz/cm 2 High granularity -  rej (at 90% e efficiency) > 100

HCRTRD - prototype - type: radiator + MWPC; 2.5 mm anode pitch - maximum drift time: ~ 100 ns - channel size: 6 cm 2

55 Fe Source Tests IFIN - HH 55 Fe tests 30% CO % Ar HV 1920 V; Readout: PASA (2 mV/fC, 1800 e rms) + ADC Converter Energy Resolution : ~10% (  ); ~25% FWHM GSI 55 Fe tests 15% CO % Ar HV 1700 V; Readout:PASA (2mV/fC, 1800 e rms) + FADC Converter Energy Resolution: ~ 8.6 % (  ); ~20 % FWHM

Beam Test Goal of the experiment: detector performance in high counting rate environment Experimental Setup: - 2 Scintillators (ToF, trigger); - 2 Si - Strip Detectors (position information); - 2 MWPC - GSI (10 x 10 cm 2 ) - 1 MWPC - Bucharest (24 x 24 cm 2 ) -1 MWPC - Dubna (10 x 10 cm 2 ) - 1 GEM - Dubna - Pb - glass calorimeter (last run) - FADC readout ; DAQ (MBS )

Beam Composition e/  vs. rate  not possible, too low e intensities at SIS  1 GeV/c  too low rates;  2 GeV/c rate dependence studies.  p  p pd pd

Beam Profile x 1 > 10 mm; x 2 > 10 mm; Si1 length  20; Si2 length  s 0.2 s

2 s 1850 V 0.2 s 1850 V Gain - 2s spill length, for protons

Average Pulse Height 15% CO2 + 85% Ar, continuous anode, 1750 V15%CO2 + 85% Ar, split anode, 1725 V 1 s 0.5 s (mV/0.74) 2 s 1 s 0.5 s 0.2 s 2 s 1 s 0.5 s 0.2 s 0 % 0.7 % 3.5 % 13.3% 0 % 2%

ToF Spectra

Pulse Height and Charge Spectra

e/  Discrimination

Pulse Height and Charge Spectra  MPV value (from landau fit of PH and Q proton spectra) as a function of rate

High Counting Rate Effect (4.2  1.2) % (3.2  2.1) % (11.7  1.8) % (0.4  1) %

High Counting Rate Effect (8.9  1.4) % (5  3.4) % (8.4  3.9) % (2.2  1.4) %

High Counting Rate Effect (6.8  1.5) % (3.2  1.1) % (5.8  1.9) % (3.4  1.5) %

Conclusions Diagnostic system not specific for hcr environment  limited performance The results of the first in-beam tests of such a geometry seem to recommend it as a solution for a major percentage of the CBM TRD subdetector. Participants: Bucharest, Dubna, GSI, Heidelberg and Münster Modest statistics  limiting factor for detailed analysis in terms of: - Beam profile - Spill profile Much to low systematics for negatives (e/  ) Although