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- Lab cold tests obtained good tuning for both LUB1 and LUB2, even 1500e for LUB2, at HV=600V.
- Presented plan for 2nd period to MCC at 4:15pm meeting: ESTB_MCC_7_13_2016_SD.pdf
- MCC meeting had brief discussion of possible effect of ESA stealing 5Hz beam. Some effects of missing pulse causing irregular effects for pulse after that a Low E beam experiment, but high E beam experiments never cared. However, still needs to verify this for MFX/LM51 tomorrow, before 9am so that both dat and night shift beam to ESA would be possible hopefully.
- Lab testing pushed up HV. For LUB1, 1KV immediately trips the 1mA max current, while 900V still hanging there but current still slowly creeping up. For LUB2, 1KV started out at 700uA (-29C) but current slowly creeping up and after several hours it eventually tripped and temperature went up to -26C.
Jul/14
Operations team: Ben Nachman, Su Dong
- Moved lab setup of cold box with LUB2 to ESA.
- The dry CO2 chamber is reversed from May to be on the corridor side while electrical connections from rack side.
- LV VDD=1.5V. I=0.33A after config.
- One temperature probe (Ts) taped to the Cu cooling tape tail from the DUT, the other temperature probe (Tg) in cold gas.
- Leakage current high initially but temperature was just -10C. 2nd access raised HV to 800V leakage current 830uA at Ts= -23C.
- After ensuring only ch=0 for RCE activated in readout, calibration ran, but threshold distribution is broad. Returned and got a quite decent RMS now. Saved to LUB2/config_rad_np_0_335: 1500e threshold, 8000e=10 for TOT.
- Made EUDAQ config SLAC_1dut_rad_FEI4A.conf
- Alignment was still tricky. Fine-Y adjustments not holding up the position. Any adjustment would trigger a long sag. Mike/Keith both thought the motor holding current may be too low. Will be looked at tomorrow before 9am by TestFac.
- Because DUT X/Y transposed, we cannot see correlations any more between MIMOSA and DUT as correlation only plots X vs 'X'.
- Horizontally we would like to move Fine-X towards +X (rack wall) by ~1cm to align with EUDET but that reached limit and cold box cable exit is touching Caladium plane frame.
- Requested access ~4:45pm. Put a ~2cm block spacer in the cold box to move DUT towards -x to recenter better in X wrt Caladium and space out the cable exit from Caladium. Also jacked up the DUT box by hand to be close to center in Y. Topped off dry ice.
- MCC notified us that LCLS MFX requested change of beam energy up to 14 GeV (but secondary always 11 GeV) which will affect our rate for a while. After reconfigure the beam spot shape changed completely with more definite edge and more uniform. Previous beam spot had a sharp hot spot of on the top right corner and more diffused spread below that.
- 6:45pm first serious data run 294. HV=800V, leakage current 200uA. Ts=-34C, Tg=-29C. ~350 hits/MIMOSA, 150 hits/evt in APIX. DUT beam window: Local X=40-75 which is 35 pixel ~8.5mm; Local Y=30-330 which is 300 pixels ~15mm. MIMOSA beam window X=200-1000 also ~15mm; Y=20-460, also 8mm.
- Noticed some 'scars' on the DUT which are straps of area with clearly lower hit density than neighboring areas.
- Ended a good run 294 to request lower rate. MCC had no clear recipe to reduce rate other than collimating to smaller beam size which doesn't really help us as it is the hit density that matters. They are trying to reach Toni Smith for advise. Ryan tried to tune this from upstream adjustments and succeeded to bring the rate down to 30 hits/shot at DUT with relatively small change in beam spot shape. We needed to make a few mm adjustments to keep both MIMOSA and DUT beam window fully contained.
- 8:34pm 2nd run 299 with DUT hit rate ~30/frame. Temperature climbing back up Ts=-32C, Tg=-27C. Leakage current 250uA. MIMOSA beam window X=150-700 (10mm) and Y=full span 0-570 and perhaps a bit more (11mm). DUT window 'X'=30-74 (11mm), 'Y'=40-260 (11mm) a bit trapezoidal.
- 9:06pm started a new run 300 when last run reached 10K event limit. Exactly same condition. Ended 21:42.
- Requested access to change DUT tilt. Had to pull out the block to tighten the rotation screw and retape the DUT Ts temperature probe. Cold box stage sagged again which needed manual repositioning. Topped off dry ice.
- Upon restarting to find the location of the DUT from remote motors, the whole DUT stage sagged to Ymin again. Only saw a lot of out of time noise hits at local X min and max edges (this was probably due to temperature not yet low enough).
- Turned off beam to do a low TOT tune of 1500e threshold and 400e per TOT bit. Calib tuning kept crashing. 600e still crashing, while 800e existing tuning still worked.
- Gaming with Y-fine stage to hold up the cold box at ~5mm below nominal (any further up push will cause full scale sag down). Cold box lid is opening a significant gap.
- Now a bit colder, returned to previous configuration and brought beam back. Noise lower. Moved DUT fine-X by -6mm, starting to see streaks. Data populating lower 'X' half of the DUT but did not dare to jack up the cold box.
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- 11:39pm started run 303 for the first streak data. They looked a bit shorter than expected typically. DUT data rate similar to MIMOSA at ~80 pixel/frame, but there are many streak clusters. Pixel TOT peak at ~5 (5*800e=4000e). This is a bit larger than expected from Bichsel calculation that predicted peak at ~3300e for 50micron silicon even without radiation damage ( foldspec_elec_11GeV_50mu.png ).
- 00:20am ended run. Let MCC took away beam. Remote power down of HV+LV.