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TAU - status

TAU - status. September 7. Status. We are on our way to better characterize the Panel background. We see some “strange behavior” which might shad some light on the subject Sensitivity is being explored We see cosmic muons with VP1.

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TAU - status

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  1. TAU - status September 7

  2. Status • We are on our way to better characterize the Panel background. • We see some “strange behavior” which might shad some light on the subject • Sensitivity is being explored • We see cosmic muons with VP1. • An accurate apparatus to hold the hodoscope and the source above the panel is in final stages of preparation • A complete voltage scan is still missing… TAU - status report

  3. Source Hodoscope Set-Up Discriminator Threshold = 50 mV Panel AND OR COUNTER Hodoscope • Quench resistors: 20 Mohm (per line) • 4 RO lines: voltage divider (100:1 Ohm) • Every RO line into discriminator -> logic AND Discriminator Threshold = 500 mV 16 pixels

  4. Hit rates in the panel Every entry in the histograms is a 5 minute counting experiment Rate rises with voltage TAU - status report

  5. Coincident rate between the panel and the hodoscope Does electron induced rate reach a plateau??? TAU - status report

  6. Excess of panel hits • Bkg rate in the panel is ~1 per minute • At 990 Volt we see: • ~12 per minutein the panel • ~1.4 per minute trigger && panel • If only charged particles induce signals than: • Bkg + Trigger&&panel = total panel rate Where does the extra 10 hits per minute come from??? TAU - status report

  7. Panel response to Xray? • Instead of the hodoscope we placed a 3mm lead plate between source and panel • Background and X-ray response measurements were done separately • the setup is slightly different so the exact rate values are meaningless…  Unrelated measurements TAU - status report

  8. Rate decay – panel relaxation time after HV off time HV Off time Measurement Measurement Time Off time = 1 hour Off time = 30 min TAU - status report

  9. Rate decay – panel relaxation time after HV off time ??? Off time = 15 min Off time = 45 min TAU - status report

  10. Rate decay – panel relaxation time after HV off time • All measurements were done exactly in the same way • We did not touch the system between the measurements • The 45 minutes measurement was the last one • Maybe its important how long was the system running before the shut-down TAU - status report

  11. Muon detection First 100 hours of measurement • Large variations in background • needs to be better monitored • Total of: • 12783 hodoscope triggers • 5848 panel signals • 20 coincident signals (panel && hodoscope) • Panel active area ~16mm2 • Hodoscope active area ~2.5cm2 • Naive efficiency calculation: • Panel efficiency for muons ~2.5% TAU - status report

  12. Beam test preparations • who is coming, minimal staff: • 1 technician • 2 physicists • 1 electronics expert • Equipment requirements: • Vacuum pump & Gas system • Gasses • Trigger system • Electronic RO • Panels • Computers • Tools • Physics study: all with two gasses and different panel areas • Detector check (background, HV scan and reproduce known results) • Pulse shape study (scope/DRS4) • Time arrival study • Rates and efficiencies • Tracking (two panels) – ambitious • Time requirement • One week of physics (4 people) • 5 days installation (2 people) • 3 days unplug & packing (2 people) Cost estimations (no flight tickets – 4 people) ~9K$ TAU - status report

  13. conclusions • A monitoring system (Temperature, HV, pressure etc.) should be installed in our lab. • A long cosmic/background measurement is needed in order to reproduce the large variations in background rate • Temp and HV should be monitored during the measurement • Rate decay after some HV off time can mean: • A characteristic of the panel which should always be taken into account in future experiments • A Temperature/HV related effect which was also manifested in the long cosmic measurement • X-ray – we have a beam in TAU and we shall check their schedule and beam proparties. TAU - status report

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