[BTeam] minutes bteam 07/07/20

[Yves Roblin]

We first discussed the machine status. 2L03 is going to be disabled for the duration of this run. This is a 20-25 MeV hit. Jay B. indicated that we have more than enough headroom to run without it for the coming 6 weeks program.

The injector setup is going on. Today, the Hall A parity crew is working with OPS and Joe Grames to rotate the cathode to the optimal orientation which minimizes false asymetries.  They think they will be done this afternoon, after this the rest of the injector setup resumes. Optics on call will stand by to assist for transverse matches as needed (the 5MeV and the 123 MeV)

A summary of the  meetings with Hall A/Hall C staff was given. The goal is to review the status of the interlocks, locks and ion chamber procedures as well as any other item which affects beam delivery or target safety.   Several issues that came out of these were:

1) ops procedures for ion chamber calibration can be harmonized between A/C and made official.
 For all thicks targets, we have a Al Standoff which will be used to calibrate the ion chambers on a radiation length similar to the target frames. The He3 gas targets have a separate procedure that was developed by Lester Richardson and Brad Sawarsky.    The action item is to make sure the procedures that are officially used by the crews reflect that.

One issue that may have arisen last time is that the current procedure calls for immediately doing an ion chamber calibration once CW is in the hall.  This occurs prior to finding the optimal target position. Therefore, it is possible to mistakenly calibrate the ion chambers while hitting the target frame resulting in an inadequate threshold. We propose to modify the procedure to redo the ion chamber calibration after the optimal target position is found.


2) Prestartup checks should include verifying that the beam excursion software is still functional.

3) We will review the status of all the locks in Hall A and make sure conflicting locks are removed rom the system (Dan)

4) the ORFP needs to be updated to specify when and how to use the aperture tool. Currently, it is not done systematically. (Yves)

5) Mike T. is writing an ATLIS for measuring the body gradients (especially in ARC1/ARC2) . We can execute it if we have time or during regular beam studies.

6)  We discussed the issue of not having enough corrector strength at full 11GeV in Hall A to compensate for a grossly misaligned target (3mm or more). It is not clear whether or not we can move the last vertical upstream because the lead shielding for moller is in the way and cant be done without. Jay B. remarked that the better way would be of course to redo the end of the beamline like the design he has for Moller. Meanwhile, I will ask the halls for specific ranges and tolerances on their target positions and see if they can mitigate some of the excursion (Yves)











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