[Hallc_running] [New Logentry] Hall C Status and RC Meeting at 11 am

[mack at jlab.org]

Logentry Text:
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Status: The change to 4 pass got stuck on Compton ion chamber trips. The magic knob was found in the middle of owl shift, far upstream of us. The carbon hole check went well, then for technical reasons we likely took no useful elastic calibration data until this morning (problematic VTP gains, with extremely low elastic rates and relatively high EDTM rates and a hot block in NPS making diagnosis difficult). 


Notables of the last slightly insane 24 hours: 

Dave G shows that the odd FR patterns in the 50k replay are likely due to bias from EDTM events when the physics trigger rates are low: https://logbooks.jlab.org/entry/4219990 (He's brilliant. It seems a little magical that the EDTM and raster oscillators stay coherent long enough to generate these patterns, but it's real.) 

Josh C quick update on the rad damage tests of the bases without voltage regulators:Takes a licking, and keeps on ticking lol.  https://logbooks.jlab.org/entry/4220047  ( Vladimir B told me offline that the amplifier output amplitude is slowly dropping - deterioration in the gain*bandwidth product is expected - but that could possibly be mitigated by regular pi0 calibration updates.) 

Sudden announcement of no beam studies on Tuesday. 

Opportunistic LED tests by Julie R during the 4 pass change. 

Some benefit from borated poly shielding (hclog by Julie R): https://logbooks.jlab.org/entry/4220352 

The last word on 5 pass elastic calibrations by Hao: https://logbooks.jlab.org/entry/4220374 

Good carbon hole plot in https://logbooks.jlab.org/files/2023/11/4220410/nps_hms_coin_2899_50k.pdf . (See the FR plots toward the back. The hole is heavily diluted by EDTM events.) 

Problematic elastic data plots in the 50k replays: https://logbooks.jlab.org/files/2023/11/4220443/nps_hms_coin_2901_50k.pdf 

Charles cuts thru the confusion with his mental machete and identifies new FADC gain parameters (used to pass energy to VTP) as the likely source of essentially zero NPS rates: https://logbooks.jlab.org/entry/4220474 

Sudden announcement that injector gun work, etc. will take place on Wednesday. This is effectively a super-maintenance day, from 6am to 6pm. (So much for understanding the beam polarization the last week.) 

Temporarily switching to an HMS3of4 trigger, and lowering EDTM rate to 5 Hz, gave somewhat useful 50k plots starting with run 2903: https://logbooks.jlab.org/entry/4220491  

Ed B walked in the door as day shift SL, quickly understood the above mess, and his shift summary is starting to look like a best-seller: https://logbooks.jlab.org/entry/4220498 

Dave G recommends that the JT7,8 repairs be scheduled this afternoon. Heidi and Lars are in the loop. 


Schedule for discussion at the 11 am RC meeting:

Tue - take 4-pass elastic data

Wed - long maintenance day. A good time to move the calorimeter to 3m to resume physics production? Handoff to Hanjie. 

Thurs, Fri -  will Dave G finally get a Moller measurement here? 


We will meet at 11 at the usual place and on zoom at https://jlab-org.zoomgov.com/j/1617015555?pwd=L09IQ216dml6ZmM5ODExVjFsMX... .

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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/4220568
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