[Halla_running] [Revised Logentry] Status update

[sanghwa at jlab.org]

Logentry Text:
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After the Compton tuning yesterday, we got beam back for production around the end of day shift. As we were getting the production running back, many things got mixed up and didn't go right. Here is what happened in chronological order:

- Adjusted upstream Hall A optics to optimize compton background rates, 1C19, 1C20 and 1H04A quads adjusted
- Compton rates checked out, good to go through the chicane
- Target #5, 70 uA, regressed detector width increased by > 10 ppm
- Concerning it's close to the end its life time, changed the target to #5 -> #7
- Target 7 was commissioned before, but did spot check on #7 with nominal (12x7.2) and large (18x10.8) raster sizes to be safe
- Detector width still around 110 ppm. Found out that the raster size was set to 12x7.2 but the coils didn't ramp. Therefore, we were running with large raster. Also found that FF was on while FFB off.
- Raster current set properly for 12x7.2. FFB, FF, RF off.
- Regressed detector width is around 103 ppm. Turning on FFB resulted in increasing compton bg rates significantly. Note that FFB was not calibrated and therefore using old data to correct.
- Backed out the "Compton tuning" optics, asked for straight through beam
- Data seems to reproduce what we had before the Compton tuning yesterday. Stayed on this setting and ran production throughout the night


This week, we are trying to align a series of auxiliary measurements. Stubby/blinded quartz test is scheduled for today's DAY shift. We are now in controlled access for the preparation. Once we finish with the access (estimated for 2h), Dustin will run the measurement. In the meantime, our Compton experts will work with optics experts at the MCC to understand what we had and to discuss about the further plan.
While we are having the access, Hall B injector work is ongoing to address the modulation of the Hall B beam. 

Notes for shift crew
- Operation restriction updated, now we should ask for 71uA.
- Check to see actual size change on the scope when change the raster
- Troubleshooting for charge feedback (https://logbooks.jlab.org/entry/3724952)

Access this morning
- Detector config change for stubby quartz measurement (Dustin, Chandan, Devi)
- Jack and techs (adding more shielding)
- Chuck (reset rpi8 to fix the LHRS HV control)


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This is a plain text email for clients that cannot display HTML.  The full logentry can be found online at https://logbooks.jlab.org/entry/3725201
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