[Rgc] [Revised Logentry] RC Daily Summary August 13, 2022

[yprok at jlab.org]

Logentry Text:
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Friday, August 12

Day Shift: Beam is back. We have optimized  raster parameters for the 15mm NH3 cell.  Runs 16658-16660 were taken while over-rastering the target. Target polarization is slowly going up, reaching 41% in the morning.  Following owl shift's problems with the beam leakage from Hall C, we performed the bleedthru test with the laser off and our slit open/closed. Regardless of the position of the slit, and with our laser off, we register up to 1.2nA in Hall B. This problems was communicated to the PD. At 3pm PD informs us that the bleedthru current was brought down to 0.17nA. 

Swing Shift: Accelerator continues to work on the bleedthru problem. By 9pm they inform us that they have exhausted all options, and our bleedthru current still varies between 0.5 and 1.2 nA. We performed 2 Moeller runs with the 4nA and 10nA beam, resulting in 72% polarization with the 4nA beam, and 82% with the 10nA beam.  These studies confirm our concern that the Hall C beam dilutes Hall B's beam polarization. 

Saturday, August 13

Owl Shift: Resume data taking on NH3. Experienced problems with dc42 roc, and BMT HV trips. 
Day Shift. Continue taking data. Target polarization is 50% and rising, Bleedthru test shows 1.2nA current from Hall C. This problem is again communicated to the PD. 

Plan for the rest of the weekend: continue to take data on NH3.  Switch HWP to OUT during the swing shift on Saturday.  

There will be no RC meeting today or tomorrow unless requested by the collaborators. 

Data taking progress:
Day 4.0 nA on NH3 (HWP IN), completed runs 16659(26M), 16660(19M) 
Swing 4.0 nA on NH3 (HWP IN), completed runs 16664(5M), 16665(63M)
Owl 4.0 nA on ND3 (HWP IN), completed runs 16666(28M), 16671(55M)

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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/4028354
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