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 ID: 419797
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Slide1
TAU - status
September 7Slide2
Status
We are on our way to better characterize the Panel background.
We see some “strange behavior” which might shad some light on the subjectSensitivity is being exploredWe see cosmic muons with VP1.An accurate apparatus to hold the hodoscope and the source above the panel is in final stages of preparationA complete voltage scan is still missing…
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TAU - status reportSlide3
Panel
Source
Hodoscope
COUNTER
Discriminator
Threshold = 500 mV
Discriminator
Threshold = 50 mV
OR
AND
AND
Hodoscope
16 pixels
Quench resistors: 20
Mohm
(per line)
4 RO lines: voltage divider (100:1 Ohm)
Every RO line into discriminator -> logic
Set-UpSlide4
Hit rates in the panel
Rate rises with voltage
Every entry in the histograms is a 5 minute counting experiment
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TAU - status reportSlide5
Coincident rate between the panel and the hodoscope
Does electron induced rate reach a plateau???
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TAU - status reportSlide6
Excess of panel hits
Bkg rate in the panel is ~
1 per minute
At 990 Volt we see: ~12 per minute in 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???
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TAU - status reportSlide7
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
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TAU - status reportSlide8
Rate decay – panel relaxation time after HV off time
HV
Time
Off time
Measurement
Measurement
Off
time = 1 hour
Off
time = 30 min
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TAU - status reportSlide9
Rate decay – panel relaxation time after HV off time
???
Off
time = 45 min
Off
time = 15 min
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TAU - status reportSlide10
Rate decay –
panel relaxation
time after
HV off time All measurements were done exactly in the same wayWe did not touch the system between the measurementsThe 45 minutes measurement was the last oneMaybe its important how long was the system running before the shut-down
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TAU - status reportSlide11
Muon detection
Large variations in background
needs
to be better monitoredTotal of: 12783 hodoscope triggers
5848 panel signals20 coincident signals (panel && hodoscope)
Panel active area ~16mm
2
Hodoscope active area ~2.5cm
2
Naive efficiency calculation:
Panel efficiency for muons ~2.5%
First 100 hours of measurement
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TAU - status reportSlide12
Beam test preparations
who is coming, minimal staff:
1 technician
2 physicists 1 electronics expertEquipment requirements:Vacuum pump & Gas systemGassesTrigger systemElectronic ROPanelsComputersTools
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)
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TAU - status report
12Cost estimations (no flight tickets – 4 people)
~9K$Slide13
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 measurementRate decay after some HV off time can mean:A characteristic of the panel which should always be taken into account in future experimentsA Temperature/HV related effect which was also manifested in the long cosmic measurementX-ray – we have a beam in TAU and we shall check their schedule and beam proparties
.
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TAU - status report