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10:30pm MCC thought they are close to be done with tuning so we started to move Caladium coarse X in reduced x direction and running the Caladium only readout. Before reaching the beam spot, the secondary scatter was ~50 particles/shot but once beam spot came into the frame, that turned to be more like 2000/crossing. Beam spot was also very wide in X ( more than the 2cm MIMOSA aperture). Asked MCC to reduce rate and spot size. a few tries didn't make much impression until a move to close down SO10 SL-10 to -0.5. That brought the rate down to ~100 particles/crossing. Beam spot is filling good fraction of aperture ans looks like a good tuning setup to start with tomorrow. The Caladium XYstage X/Ycoarse RBV=115.4/3.8mm (Y is very close to min limit). Run 336 tuning beam spot picture below.
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- Debug the RD53A 0x0A53 (C) setup
- Special timing tests
- Cosmic telescope self-trigger mode ? Recovering 2nd module ?
- Systematic RD53a data taking runs
- Cosmic telescope data runs to map out all device areas
9:45 AM Beam turned on with ~40 hits per beam on MIMOSA
9:45 AM to 10:00 AM Run 408. Su Dong and Sanha tuned the telescope and the RD53A location to center the beam. The bottom ~30% (x=0-108 Synchronous FE causing noise to other FEs) of the RD53A is not configured for read-out, so we focus on covering 130px and above only (center the beam at mean roughly 260px).
10:00 AM to 10:20 AM Run 409. Su Dong and Sanha running a long run with the tuned telescope & RD53A location. 40 hits per beam on MIMOSA, 15 hits per beam on RD53A. This rate seems too high, so Su Dong talked to the beam control team to reduce the beam density, while keeping the same coverage.
10:25 AM Discussion with Ben decided that we should aim for 1 particle in RD53A per shot. We are 2-3 times high wrt that. The beam spot is nicely spread over almost the full MiMOSA area quite uniformly so that we should try to preserve. Called MCC to request reducing rate which they offered to try inserting the screens which didn't seem to make that much difference until the last screen. Carsten called to complain the strategy as he believes inserting screen after SL-10 might distort the exit particle moment spectrum to let in some potentially unwanted low momentum particles. Carsten talked to MCC for a revised configuration to work on the SL-10 slit to narrow the momentum phase space but hopefully not disturbing the large uniform spot. This appeared to have returned us to the previous state with 8-9 partcles on MIMOSA. Called MCC to try narrow SL-10 from -0.6mm to 0.7mm. This lowered the MIMOSA rate to 2 or 3 particles while RD53a was ~0.6. So we tried to go back some to 0.65mm which brought the rate back up to (cluster multiplicity) of ~6 and RD53a having ~1.5. Decided to keep running with this. Carsten noted that the SL10 readback was still front/back 0.69,0.7 which implies that the SL10 drive to 0.65 is beyond the actual drive precision (SL10 is a very heavy object) not nudged it enough to make the difference. For further tweaking of the rate up, Carsten recommended only driving only the back edge of SL10.
11:00 Run 418 with the new beam setup started EUDET+RD53A
11:35 Run 420 started with same conditions