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UM PPS Lab Activities

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

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UM PPS Lab Activities

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  1. UM PPS Lab Activities PPS meeting June 13, 2013 Claudio, Curtis, Dan, Riley

  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.) UM PPS Activities

  3. Setup 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%) UM PPS Activities

  5. Trigger 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 Signal charge well above the cut The hit distribution variations (besides the low statistics) are mostly due to the scintillator paddles and PDP lines efficiencies Dead channels for part of the run UM PPS Activities

  7. Arrival Time Distribution UM PPS Activities

  8. Uncorrected Hourly Efficiency UM PPS Activities

  9. Final Notes on Gas tests & More • 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 UM PPS Activities

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