[Hallc_running] [New Logentry] Beam update

hszumila at jlab.org hszumila at jlab.org
Mon Feb 12 08:50:08 EST 2018

Logentry Text:
We started to receive beam in the hall this morning around 4am. We looked at the beam on the yag, and it looked wide (https://logbooks.jlab.org/entry/3530648). Beam size was a bit spread out and probably the culprit for our target ion chamber trips that limited us to 35 uA this morning. We took a carbon hole run (https://logbooks.jlab.org/entry/3530657), and it looked reasonable in the SHMS. Jay has a new match that they are testing now that should shrink the beam size back to what we expect. Eric P is checking the DAQ as there were some missing reference times in the 6% C target run this morning (this results in about a loss of 1/3 the events, see https://logbooks.jlab.org/entry/3530742). The EB also produced an error that shift takers should be aware of: https://logbooks.jlab.org/entry/3530697. These events did not show up in the initial replay of the 50k. This morning, we were able to take the 6% C singles and most of the LH2 singles run. When the beam comes back, we need to check
  the profile and take a bit more (10 minutes or so) LH2 singles before proceeding to the LH2 coin at the Q^2=14.3. 

The accelerator is still tuning the beam for us. There was some bleed through in Hall B when Hall C was running. This issue and the beam profile in Hall C needs resolved before we officially get the beam back for production. In the meantime, they expect to start us at 35 uA again, give Hall A 20 uA, and try to slowly increase our current over time. No RF recovery is planned for tomorrow. 

Action item that needs attention:
-> The unser temperature is not regulating (https://logbooks.jlab.org/entry/3530289)

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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/3530744
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