[Hallc_running] [EXTERNAL] RC Daily Update

[Abhyuday Sharda]

Yesterday during DAY we had no beam due to the planned maintenance day. Beam came back at ~9:15pm during SWING. Beam position was checked by taking data at Carbon hole. There are some concerns with the apparent (but small) horizontal offset (https://logbooks.jlab.org/entry/4452356 ) but Dave mentioned that the aperture in the cryotarget is large enough to accommodate this change so we won't be changing beam position. The HMS Dipole NMR field wasn't locked till 7:04am the next day. Dave made a log entry about why it wasn't locked (https://logbooks.jlab.org/entry/4452278 ). Data taking was smooth during OWL till the SHMS Horizontal Bender magnet interlocked at 4:16am (https://logbooks.jlab.org/entry/4452224 ), seemed to be related to the magnet temperature. I contacted the magnet expert on call (Joe Beaufait) who was unable to fix the problem remotely so had to come in and was able to fix the issue. Data taking resumed at 6:18am till beam was shut down for the Wien angle change and Hall B pass change. Beam is expected to be back by late DAY.

It was agreed that we have reached our statistics goal for the current setting z=0.34, thpq=2° so we took advantage of the downtime to change the SHMS angle (https://logbooks.jlab.org/entry/4452395 ) and momentum (in progress). The GUI had to be set at Once the beam is back we will start data taking on the z = 0.5, thpq = 5.2° (e,e'π+) setting, LH2 target. Note- The GUI had to be set at 13.52° for the camera angle to be 13.51°, I will communicate this with future shift takers so this doesn't cause confusion.

Updates from the accelerator-
- There is a test of tune beam + Continuous Wave beam that will be done around 10am tomorrow. Will take around 10-15 minutes. We can take data using this beam but we need to make sure to start a separate run using this beam. I will communicate this with the shift takers.
- The accelerator folks are ready for the beam energy measurement on Monday (despite it being a holiday).

Reminders/Lessons learnt-
Please make sure to lock the HMS dipole NMR field. There are detailed instructions on the wiki under the bookmark 'Information for Shift Takers'. If you're still unsure let the TO or RC know.

Shift Summaries
8/27 DAY- https://logbooks.jlab.org/entry/4451726 
8/27 SWING- https://logbooks.jlab.org/entry/4451916 
8/28 OWL- https://logbooks.jlab.org/entry/4452122 

LH2 fan speed test-
Silviu is able to support a test of the impact of the fan speed on the LH2 target on Friday, starting around 11 am. His availability is limited, so Dave proposed the following plan-

1. Set up for HMS DIS (no need to change kinematics) ps4=0.
2. Ask for a “high” current: 50 to 60 uA.
3. Take 15 minutes runs at: 1) 45 Hz (the present fan speed), 2) 35 Hz (close to what we’ve been seeing much of this run) 3) 25 Hz (lower limit of what we’ve seen)
4. If Silviu has time, repeat the above steps at 20 uA.

We will have the regular RC meeting at 2:30 pm today in the counting house conference room.
Zoom link: https://urldefense.proofpoint.com/v2/url?u=https-3A__jlab-2Dorg.zoomgov.com_j_1618227115-3Fpwd-3D8JkhFg6YNesVc3HNgWjwUSIKIu&d=DwIFaQ&c=CJqEzB1piLOyyvZjb8YUQw&r=u5tNM-t17TvnEMN44CWm5qVyE415lk08NPqyR_N_lLM&m=Z0C46E7V0aQD_OYXPTadY4i-a-prm8JBouEuyzjJWWHeVKmBzE0To0eQsjYSngA9&s=TtCvH8fgwNnA70Gv06fBnzsuHY1CDzRBnbdeB8lVO7Y&e= ... <https://urldefense.proofpoint.com/v2/url?u=https-3A__jlab-2Dorg.zoomgov.com_j_1618227115-3Fpwd-3D8JkhFg6YNesVc3HNgWjwUSIKIu5SvP.1&d=DwIFaQ&c=CJqEzB1piLOyyvZjb8YUQw&r=u5tNM-t17TvnEMN44CWm5qVyE415lk08NPqyR_N_lLM&m=Z0C46E7V0aQD_OYXPTadY4i-a-prm8JBouEuyzjJWWHeVKmBzE0To0eQsjYSngA9&s=QC4ytp8apvI5Osxk_7uV345cae0_P6ExZQaYNcRuBVE&e= >
Meeting ID: 161 822 7115
Passcode: 253463
Dial-in: 833 568 8864


Sincerely,
Abhyuday Sharda

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