UM PPS Lab Activities PPS meeting June 13
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 (~6 m. V x 100 attenuation) and slow (~25 rise time) signal • Discriminator thresholds down to the minimum 30 m. V and RO card with only x 10 attenuation • At 680 V BKG much lower than rate with the source, but already at 685 V the two rates are almost indistinguishable • Comparing He(: CF 4 90: 10) with Ar(: CF 4 90: 10), we expect a smaller pulse in Helium mixtures because: – Less electrons: ρ(He)=0. 178 g/cm 3 Vs ρ(Ar)=1. 782 g/cm 3 – Harder ionization: Ei(He)=25. 5 e. V 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 2
Setup June 13, 2013 UM PPS Activities 3
Micro. DAQ Run VPE He 90% CF 4 10% at 730 torr Run over the weekend at 682 V with CR trigger 31 HV lines @ 100 MΩ and 24 RO lines Pixel 0. 1”x 0. 1” Scintillator Paddles 3” x 4” fractional acceptance=31*24*. 01/12 =0. 62 • 2, 185, 200 PPS hits in 46 h 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 Ar. CF 4 efficiency • • Channel 0, 18, 20 dead the first 48 h (Dan clamped the RO card connector) fractional acceptance~0. 54 eff~0. 3%) June 13, 2013 UM PPS Activities 4
Trigger Pulse large in charge and narrowly peaked in ADC and time (TDC) No cross talk on other channels Scintillator trigger stable in time June 13, 2013 UM PPS Activities 5
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 June 13, 2013 UM PPS Activities 6
Arrival Time Distribution June 13, 2013 UM PPS Activities 7
Uncorrected Hourly Efficiency June 13, 2013 UM PPS Activities 8
Final Notes on Gas tests & More • A bottle has been vacuum pumped for 24 h • VPE pumped down to 16 m. Torr (no baking) to be filled with a similar gas combination • Today fill a bottle (then VPE) with 99% He 1% CF 4 • Future mixtures to be tested: 99%He 1% CO 2/Xe (these will require panel baking) • Theo is starting to write the Lab. VIEW program to control the PS to implement the Voltage reversal June 13, 2013 UM PPS Activities 9
More Activities • HV board tested while reading out signal on MP 1: 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 m. V after 30 d. B (=31. 62 times) inline attenuation discriminator lower limit, but for negative signals inverters needed June 13, 2013 UM PPS Activities 10
- Slides: 10