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- 09:30 FE65-P2: An analog scan looked pretty bad at first:
- 09:30 FE65-P2: ran tune_globalthreshold and tune_pixel threshold and got okay results from an analog scan:
- When running YARR we get an error for each scan: ERROR # virtual void Fe65p2DataProcessor :: process() : Received data for channel 1 but storage not initialized!
- 09:42 We have beam, are current calibrating LUB2 using config_rad_np_0_271
- 10:10 started run 649 with config SLAC_LUB2_with_FE65P2 and YARR producer; currently blasting us with 400 hits per plane TA = -35C TP = -43C; events wouldn't build so restarted RCE/Mimosa, etc.
- 11:03 stopped run
- 11:34 Run 650 TA = -31C TP = -43C Moved DUT back up 4mm to sit in area that avoids dead pixels. After running for about 1600 hits this was actually a worse position so repositioned back -4mm
- Apix is not showing as many hits as all other mimosa planes, even those behind the DUT. We tried using the previous config from yesterday, didn't improve things. For the July testbeam the LV was set to 1.5V with 0.33 and for this run we had 1.2V.
- 12:37 Considered RCE couldn't handle the high particle rate so we asked MCC to lower to ~20 electrons. Did not improve things. Requested an access so we could increase the LV to 1.4, top off the dry ice, and check to make sure we were still in the beam.
- 13:13 Run 656 The first run the telescope had about 300 hits per event while DUT had 4.5. After the access the telescope sees 21.5 and the DUT sees 1.9. The mimosa has different pixel size (2) so accounting for that the number of particles the telescope sees is 10 per pulse and the DUT (with cluster size 1) sees 1.9, so this ration is in the same order of magnitude. Pixel ToT distribution is lower than yesterday's
- 13:40 Tried retuning LUB2, did not improve ratio of hits per event of Mimosa/DUT - still about 11/3
- 15:00 Retuned Run 658 -> TOT still doesn't look great
- Configs:
- 349 thresholdscan 1000v
- 350 thresholdscan 600v
- 351 thresholdscan 400v
- 16:35 Access to monitor leakage current, turns out the HV current was at compliance. It was tripped at 400V, so all runs today were without HV operating. Changed the current limit and set up a camera to monitor HV and leakage current
16:50 started run 662 at 400V. Planning to run 10 minutes at a time in 200V increments
Run Comment 662 400V 20uA 663 600V 34 uA 667 800V 51uA 668 1000V 70uA - Runs 662-668 were very noisy RCE needs to be restarted almost everytime we start a new run
Tried running read_rawData script on some FE65-P2 data from earlier (run 649) that we scp'd to shieldtoad but program hangs
17:45 Retuning 1500e@800v -48C config: 392
Run Comment 669 800V 47uA - very low hits per event again. Looks like the tuning is masking lots of pixels because the noise has gone down.
Weird behavior could also be because the temperature is too low?682-698 High rate area scan with ~80 hits/event perpendicular beam. HV=800V, ~200uA, rising with gas temperatures from -35C to -28C. Config=SLAC_1dut_rad_FEI4A (calib=335, Thr=1500e 8000e@10TOT). Stepping through windows of 7x3mm. See Twiki spread sheet for run details. 701-716 Low hit rate (~3 particles/event) efficiency scan for left column and more top regions. HV=800, current 250-380uA gas temperature -28C to -25C, with same configuration as above. 710- HV bias scan from 1.1KV down to 0.6V. Gas temperature -34C stable after dry ice top off. - The data taken with config-392 showed big unexpected holes. We examined the enable masks in that calibration and found that majority of the pixels are disabled and only some island of pixels are enabled. The block temperature is <-50C ! which is too difficult for calibration to work. When dug out the July perpendicular run config SLAC_1dut_rad_FE14A to run with that (only some pixels on the edges disabled), most pixel back to life again while the left and bottom of the DUT got some more noise hits which is expected from the too cold temperature.
- Requested access to warm up somewhat and take the opportunity to drop a 1.3" wide wood chip into the DUT box between the dry ice partition plate and DUT base block to prevent direct contact and let DUT to follow more the gas temperature and hopefully not following only gently the dry ice.
- Upon restart we got bogged down by DUT readout errors which was rather resilient to reboot HSIO. Went for access and lowered the LV 1.4V->1.3V which solved the problem nicely. So the lessons is that 1.4V is only workable at very low temperatures and was the cause of the many DUT readout errors. We know 1.2V worked nicely at room temperature so that one should not need to run above 1.3V.
- Decided to go after a DUT scan at high rate to map out bad pixels first. Requested MCC to (fully) open slit10 to 10mm which gave ~80 pixel hits/event for the scan, during Run 682-698 with ~2000 each stepped over 7x3mm windows. A beam line magnet tripped briefly which took a way the beam for 15min. As temperature rising through these runs, the noise pixel gradually fading out.
- 2:00am recentered beam spot on the left hand vertical strip to take low particle rate fine quality efficiency data. Asked MCC to close down slit10 and looks like at 0.5mm one cannot see APIX LVL1 timing peak any more so we settled for slit10=1mm. The PIXEL hit rate for good MIMOSA planes is ~10 but when no beam this still reads ~3 which is the effective pedestal. Checking the APIX cluster LVL1 time peak size and overall DAQ plane count histogram one can derive the cluster rate/event = ~2000/650 ~ 3 which is almost perfect. Given the noise pixels around at at least the same rate, it doesn't make sense to go any lower. Offline reconstruction has to find a way to work with at least this rate.
- Low hit rate efficiency data collection on the left column start with run 701 at the bottom for 10K events per run and marching up 4mm each run.
- 4:15am Finished a full vertical stripe of low hit rate data. Decided to try varying bias. Gas temperature already at -25C and and leakage current 340uA. Making a quick HV step up, it was found that although the current was still <600uA at 1.0 KV initially, but it is not stable and continued to creep up even when we were not running. Decided to hold off bias scan until we top off the dry ice next time.
- Added two more low rate run on the top half towards the center.
- Leakage current up to >500uA. Requested access to top up dry ice. It was half empty and our top up didn't pack the full chamber to avoid going too cold.
- Upon restart, we got a lot of DUT readout errors choked the DAQ again. Had to ask for another access. This time only tried one simple thing: power down LV and unplug LV cable at PSU then power up PSU and wait until the ringing output settle before plug in the LV cable to PSU. This was sufficient to clear the problem. Many previous incidents are probably due to the same power up problem that simply did not bring up FE-I4 properly. This points to the importance to follow this LV power up ritual and check readout with a calibration in the pit before exit the access.
- The sensor leakage current dropped very quickly back to <100uA after dry ice top off. We decided to try again for the HV bias scan and this time leakage current did not run away even at 1.1KV. So we started the bias scan at 1.1KV in region (X=20-50,Y=220-280) from Run 710.
- 9:00 am: end of the perpendicular runs.
- 10:00 went in for an access to tilt the sensor. Some reference photos taken by Ben and SuDong. The thermocouple that was taped to the base metal is now somewhat loosely attached, hence the two thermocouple (one in the air; one on the metal) temperature readings are closer than before. Also added more ice.
- 10:40 am: Temp. measurement down to -24C and -27C. Started a new run and asked for the beam, but MCC tells us that due to MD there will be no beam until 3 PM. Somehow this information was not related to us until now. Sigh.
- 3:00 PM: MD is over, but it will take another 30 minutes before beam.