[BTeam] Hall A and C trade-off change

[Jay Benesch]

I took an initiative this morning and got the following response.   Thia agrees that Ops can reduce current to Hall A and therefore 0L04 phase offset so C beam won't cause 0R08 BLM trips at 30 uA.   

________________________________________
From: Cynthia (Thia) Keppel <keppel at jlab.org>
Sent: Friday, August 28, 2020 8:56 AM
To: Jay Benesch
Cc: Camille Ginsburg
Subject: Re: Two requests

Hi Jay,

Yes on 1.

Yes on 2 as well... Hall C has a much higher priority than A at this point. Let's go for 30 uAmps and no (:)) trips!

Thanks,
Thia



Cynthia Keppel, PhD

Hall A and C Leader

Thomas Jefferson National Accelerator Facility

1-757-269-7580

________________________________
From: Jay Benesch <benesch at jlab.org>
Sent: Friday, August 28, 2020 7:31 AM
To: Cynthia (Thia) Keppel <keppel at jlab.org>
Cc: Camille Ginsburg <ginsburg at jlab.org>
Subject: Two requests

Thia,

1. May I tell Ops and DC Power that you have agreed to degauss the horizontal dipole MBE3H07 and move the leads from its "bipolar" power supply to MQF3M01 so I can reduce the spot size at the pivot and beyond?  I'm not asking to do all I presented at the Hall C meeting, just this.   Six hours in the hall.  If the target breaks before the end of the run, then.  Otherwise, during the down.   Optics would remain as is during d2n.

2. CREX has received 443 C.  Gross online cuts reduce this to about 300 C "good" but in my experience with parity experiments, ~90% of the total will be usable, so 400 C.  d2n has gotten only 13 C.  Operations has to trade off compression in the injector chicane to keep Hall A Compton background down with 0R08 BLM trips due to tails on the C beam when at 30 uA.  If Hall A current were reduced to 120 uA and absolute Compton background rates were allowed to remain the same, reducing S:N from 3.5:1 to 3:1, Ops could back off injector chicane compression and reliably deliver 30 uA to Hall C with fewer trips for everyone.  CREX would get another 100+ C through the end of the run in this setup.

Thank you.

Jay