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This document presents preliminary results from long aging tests of RB1 chambers at GIF, including tests with high photon flux irradiation and without irradiation. The chambers were tested under different run conditions to check each single and double gap. The results include hit rates, currents, cluster sizes, and voltage values.
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Preliminary results on RB1 chambers at GIF • A. Colaleo • 13 March 2003 • Long aging tests of full size chambers : test under high photon flux irradiation and without irradiation and check with SPS muon beam • Test periods • November 2002– March 2003 : aging test without close loop gas system • March 2003 until end-of-year: start test with close loop gas system. • SPS muon beam: 15 days as main usersin June-July and run parasitically during the rest of time.
Edge of the chamber is now at 20 cm from the beam line (1st position ) a) 350 cm 80 cm (20 posit) 204 cm (30 posit) Chambers need to be moved during the beam test. 2nd position during beam test : 80 cm from the current position 3rd position during beam : 204 cm from the current position
Chamber position in the GIF area Cham 25 source f b 80 cm Cham 26 3.5 m
Layout of the chambers Strip 1 Strip 1 Strip 90 Strip 90 125 cm 116 cm • Different run conditions to check each single gap and double gap : • double gaps : chamber 25 and chamber 26 HV ON • up gaps HV ON and down gaps HV OFF • down gaps HV ON and up gaps HV OFF
Operation conditions in CMS Barrel Rate: 30 Hz/cm2 (safety factor included) Average total charge: 30 pC Effective operation time: 5x107 s (10 LHC years) The total expected charge is be 5 10-2 C/cm2 Operation condition at the GIF at ABS 1: Hit rate: Photon flux at ~3.5 m : Sensitivity to 662 keV photons: Foreseen hit rate: A lot of different detectors and materials in front of the source: We will collect Need 4 months of full GIF operation at ABS1 to collect 5 10-2 C/cm2 : Safety factor 3 : we need 1 year
25 26 W0/RB1/i12 W0/RB1in/1 RB1in-Left RB1in-Left 52 55 54 53 Two chambers from the production set All information are stored in QC2-QC3-QC4 databases DG_Forward_ID DG_Backward_ID DG_Forward_ID DG_Backward_ID Chamber 25 and 26 have been tested in Bari with cosmic runs: QC5 Threshold 200mV Gas mixture96,5% C2H2F4 , 3,3% I-C4H10 0.2%SF6
First results on RB1 tests • 4 sets of data available at the moment • 25 November (test 1) • 9 December (test 2) • 1 February (test 3) • 7 March (test 4) • Data were taken under the following conditions • Source off • Filters 1 (ABS1) during the 4 tests • Filters 10 (ABS10) during 2 tests • Filters 2 (ABS2) during the first test • Results on • rate (by cluster counting) • currents • cluster size • Hit rate profile • Voltage values are normalized at T=293 K, P=1010 mbar • Gas Mixture: C2H2F4 /C4H10 /SF6 = 94.6/5.1/0.3 • Electronics threshold: 200 mV single and double gap results
Rate by cluster counting All hits registered from consecutive strips within 25 ns time window are combined into a cluster. All clusters inside 1.6 s TDC window are taken into account to evaluate the rate. Test 1 Chamber 25: Double gap results Comparison ABS 1-ABS 2- ABS10 T=293 K, P=1010 mbar
Test 1 Chamber 26: Double gap results Comparison ABS 1-ABS 2- ABS10 T=293 K, P=1010 mbar
Chamber 25 Test 1 Comparison singleand double gap – ABS 10 T=293 K, P=1010 mbar
Chamber 25 Test 1 Comparison singleand double gap – ABS 1 T=293 K, P=1010 mbar
Efficiency checks start at the beginning of February (test 3): 3 small RPC used for trigger during the efficiency runs (cosmic trigger with source OFF). Logic AND of ORed signals from each chamber: 40cm x40 cm
Rate by cluster counting Comparison between 4 test periods @ ABS1: counting rate Chamber26 Down gaps on
Rate by cluster counting Comparison between 4 test periods @ ABS1: counting rate Chamber 25 Down gaps on
Rate by cluster counting Comparison between 4 test periods @ ABS1: counting rate Chamber 26 UP GAPS ON
Rate by cluster counting Comparison between 4 test periods @ ABS1: counting rate Chamber 25 UP GAPS ON
Rate by cluster counting Comparison between 4 test periods @ ABS1: counting rate CHAM 26 DOUBLE GAPS ON
Rate by cluster counting Comparison between 4 test periods @ ABS1: counting rate Chamber 25 DOUBLE GAPS ON
Mean cluster size Mean cluster size for all cluster in 1.6 s TDC time window are shown
Current vs HV Comparison between 7 test periods @ ABS1 Chamber 25 11 mar 11 mar 6 mar 6 mar 27 feb 27 feb 10 feb 10 feb 31 jan 31 jan 13 dec 13 dec 25 nov 25 nov
Currents vs HV Comparison between 7 test periods @ ABS1 Chamber 26 11 mar 11 mar 6 mar 6 mar 27 feb 27 feb 10 feb 10 feb 31 jan 31 jan 13 dec 13 dec 25 nov 25 nov
Hit rate profiles: Cham 26 HV = 9400 V TEST 4 Forw 26 ABS 1 Double Forw 26 ABS 1 DOWN Forw 26 ABS 1 UP TEST 3 Forw 26 ABS 1 Double Forw 26 ABS 1 DOWN Forw 26 ABS 1 UP
Collected charge 25_up_forw The chambers are with HV ON at 9000 V all time We are continuosly monitoring the currents The integrated charge (mC/cm2) in about 2 mounths for each gaps are: 25up_forw 4.8 25down_forw 7.2 25up_back 6.5 25down_back 6.3 26up_forw 7.9 26down_forw 8.4 26up_back 6 26down_back 7.2