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- Access to add more ice.
- 9:00 PM: Running now at 800 V with a 145 uA leakage current. Tried again to reduce the rate by moving S10 to 0.5 mm, but saw no particles on the DUT! Now to 2mm to verify that the DUT still exists. Don't want to upset the operators, will wait for shift change to go back to 1mm.
- 00:26: asked to increase slits from 1 to 2 mm. Particle count before was ~10 (but double peak, so ~5) and after is ~30 (still double peak, so ~15). We got this from looking at the cluster multiplicity in the 3rd telescope plane (basically no noise).
- 1:10: asked for the S10 slits to be moved out the whole way (100 mm) so that we can quickly scan the sensor.
- 2:35: LCLS beam down for a user (they didn't tell us...had to ask when we noticed no beam). They say they will 'give up in 30 min' and revert back if they can't get the configuration they want. Powered off the HV in order to preserve the temperature.
- 3:55: Asked to go back to the 2mm S10 spacing to take some final data with LUB2.
- 4:25: Call from ACR - lost beam because LCLS users want 30 Hz. No comment on when it would be back.
- 4:35: Asked for an access to swap LUB1 and LUB2 (might as well while we have no beam).
- Just swapped LUB1 and LUB2, LUB2 back in freezer. Ran digital and analog scans during access and looked okay out of the box using LUB2 config. The threshold was not so great, but that could just be the threshold. Will use the proper one now. Adam (MCC) said that LCLS user is back to 120 Hz, so we could have beam again soon (Adam is by himself tonight !!!)
- Temperature very warm (~-10), tried turning on HV but tripped the power supply. Turned off HV and now waiting for temperature to cool back to where it was before.
- 7:00: Went in for an access to add more ice (now out of ice) because the rate of temperature decrease is too slow (done at 9 am!)
- Access to examine HV and found the Bertan (orange) HV it tripping consistently at <300uA so we gave up that HV supply and switched to the green dumb HV supply.
- Threshold scan failed after 3rd mask stage, coupled to the abnormally low LV current (30mA). Went for access and found that threshold calibration only works with bias off and only after running the threshold calibration the LV current shows some normal value of ~300mA.
- Leakage current uncomfortably high at ~500uA while still only at 600V. The -25C temperature is just not sufficient for running. We took some scoop of dry ice out of the chamber and sprayed into the DUT box which did the trick to get temperature down right away. The leakage current is down to <100uA.
- Ramping up HV slowly while the Lv current is normal after a threshold scan is the only way to get both HV and LV up. When HV reaches ~770V, current suddenly goes crazy even when HV current is <100uA which trips off both HV and LV. So settled to HV=700V as the only way to run.
- Switch to configuration SLAC_LUB1_only (which points to LUB2 335 calibration).
- We can now run and seeing nice streak data but EPICS Caladium displays of temperature etc all dead. Panels for Caladium mover are all flashing error. Mike is out today and Doug came over to help. We rest the IOC but that didn't seem to do much. I recalled the similar incident before needed cycle Beckhoffs 26 power which we did that seemed to have brought things back but many setting appeared strange so that some guessed values were inserted and eventually got it to do something. We then found that driving fine stage Y up had sagging problem again which fortunately is just a matter of going to the fine Y motor advanced settings to enable the hold current and keep enable.
- Beam is ~150 particles/event, even at
- Run 744 is a beam spot playing run with large number of events on a left vertical strip. We cannot go left any further Yfine stage reached bottom limit. After some fiddling we verified we are sitting just inside the tall vertical edge of the beam spot which is the tallest part in Y so that we have the widest streak street in the horizontal direction when viewing the APIX hit map (DUT is rotated).
- Run 745 started from right hand APIX edge map to scan for uniformity. We were moving Xfine stage during the run when reach target for a vertical strip. We stopped in the middle of the DUT when beam stopped.
- Run 748 746 continued, but we realized that the beam is back to single pulse ! and didn't last for long. We notice the histogram updates were slow and even implied a lower particle rate but looks like that was due to the online monitoring went into some jammed mode and not to respond to any clicking. Had to kill it and restart everything. Run 748 is good (4 mm away from hard stop).
- Beam goes on/off as MCC is playing between single and double pulses.
- We are ready for the low rate run. Asked MCC to turn down the rate. They dialled slit 10 to 0.5mm which initially just dropped everything but eventually managed to stay with that. The rate reads 20 pixels per event on Mimosa (single pulse mode) and APIX looks like 3-4 streaks per event, which looks just about right for us.
- Started low rate data from Run 750 on the left end (x=10-30) while beam is back to double pulse mode with varying relative strengths between the two pulses.
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