Long Run Test on Microcavity #2

PPS meeting 01/06/2015 - The UoM guys

SETUP90Sr (4.7 mCi in 1993)Source at ~3 inches over the panel over the pixel in line 3HV at 1100VDiscrimination Threshold at -700 mV

MC02 (W over Pt) • Baked for 3 days at T=100°C; P down to 1.310-6 bar (0.975 mTorr)• Filled Nov 21 with AAT0005 (15% CF4) at 743 Torr• Leak tested (1h measurements) OK • After an initial cleaning of the soldering of the quench resistors, 8

RO lines out of 10 are instrumented (line #4 and #5 not working)• Nov 21st AAT001b (21% CF4, 78.4% Ne and 0.6% Ar) 740 Torr

We mix according to a volumetric method- not mass. correcting for mass effects using the MFC conversion tables

“Long Run” Hourly Rate

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Zoom on Last Week

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Yesterday’s Tests• Pumped down to 0.5 mTorr and refilled with the same gas

(AAT0001b), same pressure (740 Torr)• Source position unchanged: 6.2” above the table over pixel

RO#3• At the same HV=1100V bursts are visible (rates on RO#7,8,9

even higher than the illuminated pixel)• Without the source the noise rate is very low

(a few counts per minute per channel=pixel).• With the 90Sr source the pixel rate is partially restored (around

35 Hz for line 3 vs the 100 Hz of the initial test) – Recovery the gas was deteriorated– Only partial recovery: maybe pixel deteriorated too

• Collimated 106Ru over each pixel: large rate variation + rate~1Hz, not 5 Hz as for the 52 pixels of the first MC (and NIMA)

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Plan• Longer term gas leak test for MC02

(mandatory to be sure it is leak tight. Curtis has already improved the gas tightness of gas system)

• Check more pixels with collimated 106Ru (at least to get 10 working RO lines)

• Varying the Ar fraction: already prepared a new bottle with 79.9% Ne + 20% CF4 + 0.1 % Ar

• Test changing Gas Pressure• New mixtures with N2

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