[BTeam] Hall A Energy discussion

[HyeKyoung Park]

All,
Since we have a regular BTeam meeting tomorrow, I suggest to meet and discuss further tomorrow at 1:30 at BlueJeans BTeam meeting.
Perhaps we talk about both hall A and B?
HyeKyoung
________________________________
From: Yves Roblin <roblin at jlab.org>
Sent: Monday, August 24, 2020 10:08 AM
To: Mike Spata <spata at jlab.org>; Brian Freeman <bfreeman at jlab.org>; bteam at jlab.org <bteam at jlab.org>; Michael Aiken <aiken at jlab.org>; HyeKyoung Park <hkpark at jlab.org>; Paul Vasilauskis <vasilaus at jlab.org>; ciprian at jlab.org <ciprian at jlab.org>; Daniel Moser <moser at jlab.org>; Eric Forman <eforman at jlab.org>
Subject: Re: Hall A Energy discussion

Regarding the bunch compression, it is larger than we usually run with. However, the design for maximum compression calls for up to 10.8 degrees. In practice, since the bunch is not necessarily upright, we rarely end up with this. Another limitation we had in the past is that excessive bunch compression offset ends up producing losses in the chicane itself due to the large energy spread it generates. I am actually surprised we can push 150 this way. Last time, above 4 degrees it was problematic.

This being said, if Hall A is taking productive data and we are not trashing the machine in this configuration, I would probably suggest we wait until the 8/31 pass change to address this as it will likely require adjusting other parameters to keep Hall A Compton rate low (steering, matching).

We can discuss that tomorrow at the BTeam.

________________________________
From: BTeam <bteam-bounces at jlab.org> on behalf of Mike Spata <spata at jlab.org>
Sent: Monday, August 24, 2020 10:01 AM
To: Brian Freeman <bfreeman at jlab.org>; bteam at jlab.org <bteam at jlab.org>; Michael Aiken <aiken at jlab.org>; HyeKyoung Park <hkpark at jlab.org>; Paul Vasilauskis <vasilaus at jlab.org>; ciprian at jlab.org <ciprian at jlab.org>; Daniel Moser <moser at jlab.org>; Eric Forman <eforman at jlab.org>
Subject: Re: [BTeam] Hall A Energy discussion

Good morning,

The last image<https://logbooks.jlab.org/files/2020/08/3830068/2008744.1.png> of the Lambertson that was logged had Hall A beam left of center. It may have been adjusted already and not logged. Hard to say if it's too far left of center since we can't see the wires anymore but might be worth taking a look. The comment was made this morning regarding the Hall B beam so if you are looking I would line them up as best you can.

I agree that the bunch compression is too large (>10 degrees from Eric's log) and we should not have to run like this for good transport. Definitely a topic for B-Team.

Mike


--
Michael Spata
Deputy Associate Director
Accelerator Ops and R&D
Jefferson Lab
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Cell: (757) 876-0528<callto:(757)%20876-0528>

________________________________
From: BTeam <bteam-bounces at jlab.org> on behalf of Brian Freeman <bfreeman at jlab.org>
Sent: Monday, August 24, 2020 8:21 AM
To: bteam at jlab.org <bteam at jlab.org>; Michael Aiken <aiken at jlab.org>; HyeKyoung Park <hkpark at jlab.org>; Paul Vasilauskis <vasilaus at jlab.org>; ciprian at jlab.org <ciprian at jlab.org>; Daniel Moser <moser at jlab.org>; Eric Forman <eforman at jlab.org>
Subject: Re: [BTeam] Hall A Energy discussion

Just some clarification  about the Hall A energy discussion of this morning.

  1.  Hall A is requesting a certain energy error (dp/p) -1E-4. This is an abnormal  request.
  2.  With FFB on in Energy mode,  or when running Arc 2 it does as designed and brings the error even closer to zero down to the E-5 range. So not sure what this request is about, and I believe this abnormal request is the root of the Hall A issue. (Cipran ?)
  3.  This issue with monitoring the SLMs, is that we are running 0L04 so far off crest that the spots almost encompass the entire image frame:
     *   https://logbooks.jlab.org/entry/3832990
     *   This was done to reduce Compton rates.
     *   I suggest we back out of the 0L04 change.

BTeam items for tomorrow's meeting? Yves you still on vacation?

Any others chime in, please.

-Brian
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