[BTeam] minutes of 07/21/2020 meeting

[Yves Roblin]

We started discussing the machine status. Some of the RF equipment in the NL is still being worked on as well as the refrigeration unit for NL. Expected to be resolved by tomorrow morning when we will start spinning up. The injector is setup with the transverse matching and the PBQ checks done.
High current checks at 135 uamps were done.

Regarding last time action items, we reviewed the status of the locks in Hal A and the redundant locks were disabled. The ion chamber calibration procedure is an OPS procedure, it is good for Hall A, Hall C does not have a thick target calibration, Lester Richardson and Brad Sawatzky are iterating on it.

We discussed the sequencing of the restoration and whether or not we could compress it. It was decided that we can omit the spin-up/reproducibility test and instead spin up only to 3R and do the M56, then resume.

Discussions about the adequacy of using BLMs as diagnostics (Steve). The issue being that they are not necessarily calibrated and sometimes indicate losses with no concomitant  vacuum indications. However the chronic loss they picked up last run was clearly real since we had a lot of hot stops in the higher arcs (7 and 9).  This raised the issue (Spata) of longidutinal beam setup in the injector. That is, how well do we control all beams.

Reza said that he checked carefully and for this setup, all beams are within specs but that he would like us to measure the bunchlength in ARC1 once we can.

Finally, another point Reza raised was the dynamic range of the measurements . When we perform transverse matches with the harps, we may not pickup the low level tails which may be the cause of chronic loss. Regular harps are limited to maybe 100 to 1 , pm harps may be an order of magnitude more. Mike T indicated that the diagnostic group is currently looking at this.


The M56 plan is important to keep because we ran with a completely off nominal setup last time. We could not correct the ARC1 M56 without excessively disturbing the transverse match so we corrected only half of it and used ARC2 to compensate. Mike T points out that it could be a cause for the beam loss since this occurrence roughly coincide with the advent of losses in the machine.

We have prepared snap files, we will load them, measure with the real time system and be able to tell immediately which is the better setup (we have 3)



Email me if I forgot anything.












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