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Updates on GEMs characterization with APV electronics

Updates on GEMs characterization with APV electronics. K. Gnanvo , N. Liyanage , K . Saenboonruang. outline. Performance of small GEM with Fe55 source and SRS e lectronics Experimental setup Measurement of the Fe 55 spectrum Estimation of the absolute gain

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Updates on GEMs characterization with APV electronics

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  1. Updates on GEMs characterization with APV electronics K. Gnanvo, N. Liyanage, K. Saenboonruang

  2. outline • Performance of small GEM with Fe55 source and SRS electronics • Experimental setup • Measurement of the Fe 55 spectrum • Estimation of the absolute gain • Performance the SBS proto I with Sr90 source and SRS electronics • Experimental setup • Gain uniformity and efficiency • Effect of the gas flow rate • Updates on the APV25-MPD electronics • Progress in the decoding and display software • Debugging the daq software and other issues

  3. Setup of the Small GEM chamber with 55Fe • Low pass filter used to reduce high frequency noise. • The cut off frequency for this low pass filter is 10 MHz. 3T GEM Chamber Discriminator Low pass Filter Fe55 CR-110 Amplifier 66 Ω 470 pF 150 nF Vin Vout Gate/Delay 220 pF SRS DAQ Trigger

  4. Study of the noise (rms of the apv25 channels) • Typical rmsnoise of a given APV cards from a pedestal run SRS • This rms is obtained after common mode correction of the baseline • An average of 6-7 adc counts for apv25-SRS • ~ 1200 to 1500 ENC • a cut at 5 sigma for zero suppression  ~ 6000 e- APV25-SRS on GEM readout strips

  5. 55Fe spectrum • HV = 4 kV on the voltage divider • Trigger threshold at 50 mV on GEM foil • Distribution of strip cluster max ADC counts  the Fe55 spectrum Photo-peak X-strips Y-strips Escape peak

  6. 55Fe spectrum vs. HV X-strips 3950 V 4000 V 3850 V 3900 V

  7. Gain of the small triple GEM with 55Fe • Gain from the mean ADC value of the photo peak • APV gain calibration = 238e- /adcchannel • Gain is about twice the gain we obtain from direct measurement • SRS electronics gain with external pulse is overestimated • strip capacitance and cross talk effect of the GEM readout not taken into account

  8. Performance of the small GEM prototype with 55Fe • Good chamber efficiency • Strong variation of the X/Y charge sharing with the applied voltage  Gain

  9. Setup of the SBS GEM chamber with 90Sr • The test used 90Sr source located above the 1st prototype SBS GEM chamber atdifferent locations to study efficiencies, ADC spectrums, charge sharing and other important characteristics of the chamber by varying the gas flow rates, and directions • The threshold of the scintillator was set at 135 mV throughout the test (unless specified by other values) 5 1 3 2 4 Aluminum Plate D 1-inch Diameter Hole C 90Sr Source B 1.5-inch Gap Active Area of the scintillator HV GEM Chamber 2-cm thick Scintillator

  10. Test of the SBS GEM chamber with 90Sr Hit distribution Condition: 1) 200 mL/min < Gas flow rate < 300 mL/min 2) Gas Direction: 1 3) Position: B3 4) HV = 4400 V 3 Sigma Cut 5 Sigma Cut X-strips Y-strips

  11. Test of the SBS GEM chamber with 90Sr Efficiency Calculation • Good events mean there are both hits in X and Y directions • The equation to calculate the efficiency is where NG: Number of good events NT: Number of triggers RT: Trigger rate with the source (12 Hz) RGB: Rate of good events without source (20 % or 0.24 Hz) RB: Trigger rate without the source (1 Hz)

  12. Test of the SBS GEM chamber with 90Sr Efficiency vs HV Condition: 1) 200 mL/min < Gas flow rate < 300 mL/min 2) Gas Direction: 1 3) 5 sigma cut

  13. Test of the SBS GEM chamber with 90Sr

  14. Test of the SBS GEM chamber with 90Sr

  15. Test of the SBS GEM chamber with 90Sr Average ADC in X direction Condition: 1) Gas flow rate = 290 mL/min 2) Gas Direction: 2 3) 5 sigma cut

  16. Test of the SBS GEM chamber with 90Sr Charge Ratio (X/Y) vs HV Condition: 1) 200 mL/min < Gas flow rate < 300 mL/min 2) Gas Direction: 1 3) 5 sigma cut

  17. Test of the SBS GEM chamber with 90Sr

  18. Updates on the APV25-MPD

  19. New APV25 FE with Panasonic connectors for SBS backtracker GEMs • Paolo Musico’s group (INFN Italy) is working on a new version of the APV25 FE cards with Panasonic connectors and new backplanesfor the new SBS backtracker GEM

  20. Design of ew backplanes for SBS back tracker GEMs

  21. Backup slides

  22. APV25 MPD and SRS system • We suspect an overestimation of the gain • Gain from external source is about 2 × the gain with calibration pulse • The estimate GEM gain from the APV-SRS signal size is about twice the expected gain • We need to re-evaluate the amount of injected charges • Try to access the effect of strip capacitances and cross talk ...

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