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

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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

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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

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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