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Setup for Cosmic Ray Test of VPA panel, using MiniDAQ D. Levin, F eb 8, 2012

Setup for Cosmic Ray Test of VPA panel, using MiniDAQ D. Levin, F eb 8, 2012 VPA: 600 Torr Ar CO2 (1%), filled on Jan 17, 2012 1” DESY mini- s cintillator hodoscope placed under panel at intersection of HV and readout lines. 24 RO lines, 14, HV lines.

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Setup for Cosmic Ray Test of VPA panel, using MiniDAQ D. Levin, F eb 8, 2012

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  1. Setup for Cosmic Ray Test of VPA panel, using MiniDAQ D. Levin, Feb 8, 2012 VPA: 600 TorrAr CO2 (1%), filled on Jan 17, 2012 1” DESY mini-scintillatorhodoscope placed under panel at intersection of HV and readout lines. 24 RO lines, 14, HV lines. Hodoscope HV = 850 V., trigger rate = 3.6 muons/min, located 2.5 inches under panel, and offset Run: run72406 VPA HV = 830 V. After 5 hr, 15 min, 1019 triggers, only 7 have coincident TDC hits. This is very low rate- less than 1%. However, the hodoscope is offset from the panel, and removed too far away. At 5 hr, 38 minutes into run, I bring it closer and directly under active region. Place Ru-106 source in holder, about 2.0 inches over active region on top of panel. Trigger rate is now 153/4 ~ 38 CPM. But panel coincidence rate is still low- don’t see any additional hits beyond the 7 obtained with cosmics.

  2. PDP pick-off card: Configuration: x200 attenuation. 50 ohms termination HV 200 pixel 49 Signal out to 50 ohm ribbon coax to Hedgehog Card 1 70 Heavy, 1” Ground braid

  3. Panel hookup to Minidaq CSM Mezzanine hedgehog 50 X attenuation Row 24 Row 1 Pickoff card 200x attenuation PDP VPA 600 TorrAr CO2 (1%) HV Col 1 Col 100-114 ScintillatorHodoscope To trigger logic and TTCvi

  4. Setup for Cosmic Ray Test of VPA panel, using MiniDAQ D. Levin, Feb 8, 2012 18:15 Make the following changes: Place source directly on the panel- so tha tit radiates lines 4-7, and also the hodoscope. Increase HV to 840 Lower minidaq threshold from 200 to 50 mV Take data run72410 After 2hr, 26 minutes, trigger rate = 4.5 Hz Events from Ru-106 – Triggered by hodoscope Hit distribution- corresponds to source location: Made with ADC > 50 counts (see next page) Time of hit relative to trigger.

  5. These are the ADC distributions for the first 8 channels. The good hits appear to have levels over 50. The cuts on the previous page are ADC> 50 ADC Counts

  6. Setup for Cosmic Ray Test of VPA panel, using MiniDAQ D. Levin, Feb 8, 2012 18:47 Make the following changes: Remove source 2) Leave HV =840, threshold =-50 3) Take cosmic ray run: data run72411 …check back tomorrow

  7. D. Levin, Feb 9-13 2012 • The work for the past few days is summarized here: Most of the effort has been focused on getting the MiniDAQ to work – without cross talk, and to record accurately the source on the panel in the location where the source is actually positioned. This has proved to be very difficult. • The problems: • The PPS radiates and produces hits on Mezz card even when the mezz is not hooked up. • Remedies: • ground everything, shield the mezz card, and especially ground the Pikov card. • Tried shielding the panel by placing foli on all surfaces. This resulted in HV discharges thru the glass to the foil. • Made foil covered box and placed over whole apparatus. No effect. • In the end found that the Pikov was not properly grounded. Attach ground strap. • b. Use new Pikov card with proper impedance termination. • The ribbon coax that convey the PPS signals for external trigger formation were universally bad. In every cable bundle there was at least one cable with a poor ground. • Remedy: found other higher quality 8 conductor ribbon cables- with lemo connectors. • Needed to properly attenuate at the pikov card and on the Hedeghog. • For Ar CO2 signals (600 Torr), use 200X Pikov and 50X HH card. • The panel has wildly varying discharge voltages depending on the row and colum location. The HV is at column 100-114. • For rows from 1-24 the HV needs to be varied by 10-20 V to achiev3 the same response. At other HV locations the panel easily enters constant discharge mode. • Tried using 200 Meg resistors- but the HV card I used seemed to radiate high noise levels. So still using 66 MegOhm. • Spontaneous hit rate on panel VPA has become very high on some channels.- hundred or so Hz at 820 V. • It is very hard to extract reliable results. • Enormous variation in rates across pixels. Cannot find an operating voltage that allows all channels to operate with even remotely the same efficiency. • This panel has become very difficult to use. I will re-evacuate, bake and refill with the same gas • Re-pumping and baking panel, Will refill this panel tomorrow Feb 14, 29

  8. Proper configuration for minidaqand reaodut: • 200 X pikov card • 50 x attenuation on HH • Set external discriminators to 200 mV. • Form OR of 24 channels • Send output to TTCvi trigger input • With long blue ribbon cables (about 20 m) – set • Bunch Counter offset to 4000 • Search window 75 • Threshold -150 to -250 • Match window 50

  9. Monda afternoon, 16:00 Feb 13: Re-install Panel VP-C with the 600 torr CF4 Instrument with new Pikov4 card and Hv on channels 110-124 Ramp up HV until ~ 1700 where I hear crackling, frying sounds from panel. This continues then stops. Increase voltage. Sounds return, then stop. A few pulses observed- but mostly just hear this crackling sound. Abandon further testing.

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