Upload
rob
View
26
Download
0
Tags:
Embed Size (px)
DESCRIPTION
UM PPS Lab Activities. PPS meeting June 13, 2013 Claudio, Curtis, Dan, Riley. He CF 4 Mixture Test. VPE with He:CF 4 90:10 at 730 Torr filled May 31, 2013 Small (~6mV x100 attenuation) and slow (~25 rise time) signal - PowerPoint PPT Presentation
Citation preview
UM PPS Lab Activities
PPS meeting June 13, 2013Claudio, Curtis, Dan, Riley
UM PPS Activities 2
He CF4 Mixture Test• VPE with He:CF4 90:10 at 730 Torr filled May 31, 2013• Small (~6mV x100 attenuation) and slow (~25 rise time) signal• Discriminator thresholds down to the minimum 30 mV and RO
card with only x10 attenuation• At 680V BKG much lower than rate with the source, but already
at 685V the two rates are almost indistinguishable• Comparing He(:CF4 90:10) with Ar(:CF4 90:10), we expect a
smaller pulse in Helium mixtures because: – Less electrons: ρ(He)=0.178 g/cm3 Vs ρ(Ar)=1.782 g/cm3
– Harder ionization: Ei(He)=25.5 eV Vs Ei(Ar)=15.7– Lower multiplication: np(He)=4.2/cm Vs np(Ar)=23/cm
nt(He)=8/cm Vs nt(Ar)=94/cm (N.T.P.)
June 13, 2013
UM PPS Activities 3
Setup
June 13, 2013
UM PPS Activities 4
MicroDAQ Run • VPE He 90% CF4 10% at 730 torr• Run over the weekend at 682 V with CR trigger• 31 HV lines @ 100MΩ and 24 RO lines• Pixel 0.1”x0.1” Scintillator Paddles 3” x 4” fractional
acceptance=31*24*.01/12 =0.62• 2,185,200 PPS hits in 46h 7’ (165607 sec), 137600 triggers and
224 events (coincidences) Rate ~ 13 hz eff= 224/137600 /0.62 = 0.26 % one order of magnitude less than the lowest ArCF4 efficiency
Channel 0,18,20 dead the first 48h (Dan clamped the RO card connector) fractional acceptance~0.54 eff~0.3%)
June 13, 2013
UM PPS Activities 5
Trigger
June 13, 2013
Pulse large in charge and narrowly peaked in ADC and time (TDC)
No cross talk on other channels
Scintillator trigger stable in time
UM PPS Activities 6
PDP Data
June 13, 2013
Signal charge well above the cut
Dead channelsfor part of the run
The hit distribution variations (besides the low statistics) are mostly due to the scintillator paddles and PDP lines efficiencies
UM PPS Activities 7
Arrival Time Distribution
June 13, 2013
UM PPS Activities 8
Uncorrected Hourly Efficiency
June 13, 2013
UM PPS Activities 9
Final Notes on Gas tests & More
June 13, 2013
• A bottle has been vacuum pumped for 24h• VPE pumped down to 16 mTorr (no baking) to be
filled with a similar gas combination• Today fill a bottle (then VPE) with 99% He 1% CF4
• Future mixtures to be tested: 99%He 1% CO2/Xe (these will require panel baking)
• Theo is starting to write the LabVIEW program to control the PS to implement the Voltage reversal
UM PPS Activities 10
More Activities• HV board tested while reading out signal on MP1: the hit line signal is only
large twice the nearby. • Better use charge integration (more discrimination).• Card ground shield did not reduce the small signals• Peaks are ~30-40 mV after 30dB (=31.62 times) inline attenuation
discriminator lower limit, but for negative signals inverters needed
June 13, 2013