[Hallc_running] [New Logentry] Sunday RC update for Hall C

mack at jlab.org mack at jlab.org
Sun Jun 30 13:15:02 EDT 2019

Logentry Text:
We're done with 3-pass. The 4-pass separation is in progress, along with some largely opportunistic 3C arc power supply work so we can get our beam energy measurement system back. (An email exchange errupted last nite after Sarin's post at https://logbooks.jlab.org/entry/3696646 . Steve Suhring pointed out we have another opportunity for opportunistic PS work on Monday if needed.)  

Brad will have an RC meeting at 16:30 . Yesterday's meeting was surprisingly useful, and there's a big 4-pass program imminent. 

Not so TMI follows:

SAT DAY shift -  Finished one production kin setting, then made a major (but remote) kin change to start another, but SHMS Q3 would not 
respond to the requested ~1% decrease in current. After Markus tried everything to resolve it,  we made some calls, were fairly patient, then 
asked for a controlled access to see what we could do at the PS controls. We decided to VERY carefully drop the DAC setting to the goal. Fortunately,
Markus had no problem understanding the WTF menu. Steve L started watching our changes remotely at some point, and by the time we finished, Big NC Brother 
had reset the balky communications interface. Resumed production with significant beam off periods. See Markus's shift summary at https://logbooks.jlab.org/entry/3696454 

SAT SWING shift - Completed (e,e'pi) production, then switched to elastic coincidences. Stephen made some updates to the kinematics file, also 
changing the beam energy in the file to the "Mark Jones SHMS carbon elastic" value which trimmed most of the excess fat from the missing neutron mass.
  https://logbooks.jlab.org/entry/3696628   See Stephen's shift summary at https://logbooks.jlab.org/entry/3696552 .   

SUN OWL shift - After coin elastics, the SHMS polarity was reversed so singles p(e,e')p data could be taken. Beam off at the end of the shift for pass change. 
See Richard's to-die-for shift summary is at https://logbooks.jlab.org/entry/3696670 . 

The last day was a complex program. What a great team. 


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/3696886
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