[Hallc_running] [New Logentry] RC daily update

simona at jlab.org simona at jlab.org
Wed Jan 31 10:00:04 EST 2018

Logentry Text:
Yesterday Hall C went to 5 pass. We got to "Jay's SHMS beam deflection test" around 6 pm. For a visual of the change in beam (X) position at the big BPMs H09 as the SHMS magnets are being ramped up check: 
The test was performed at 7.5 deg and 9.8 GeV/c momentum which is expected to be the smallest angle/highest momentum we will go to *during this Spring run*. The beam deflection was up to 1 cm at this kinematics setting. 

After Jay's test MCC spent some time doing the ion chamber calibrations (LH2 and C 6% A). Once that was done (shortly after midnight) we checked the beam centering on the C-hole target (new beam x and y positions and plots posted here: https://logbooks.jlab.org/entry/3524342). We could then start executing the 5 pass commissioning run plan. 

Steve Wood (shift leader during swing) spent most of his time while on shift dealing with the HMS magnets which tripped frequently and could not be kept for long at the currents required by a -6.693 GeV/c momentum setting. So we decided to give up on this momentum setting (for now at least) and go to the next highest one on the commissioning run plan, -5.816 GeV/c. To my knowledge, the highest HMS momentum setting needed for physics running this spring is 5.7 GeV/c but I will check with Steve Lassiter to see what can be done to go above 5.8 GeV/c, if needed.

During the night 3 out of the 6 kinematic settings of the HMS/SHMS tune verification run plan were covered (https://hallcweb.jlab.org/wiki/index.php/Commissioning_Plan_2017#Beam_energy_of_10.6_GeV). We are now completing the last 3 and this should put us sometime around 2 pm if beam is good. 

At that point we will take a controlled access to place the GEM detector in front of the SHMS HB. We will take low current (less than 1 muA) for about one hour (or less). Then we will make another access to retract the GEM to the side. RadCon and Jerry (Hall C tech) have been notified and they will provide support for this configuration change. 

After the GEM run we will move to the H(e,e',p) check and later into production running for the CT experiment (https://hallcweb.jlab.org/wiki/index.php/Main_Page#The_10.6_GeV_Run_Plan_.28282_hrs.29). We let MCC know that we are hoping for a higher current than 25 or even 30 muA during the CT production running.

***We will meet today at 2:20 pm*** on the second floor of the counting house (MCC meeting at 1:30 pm). The bluejeans info:

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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/3524559
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