[BTeam] Fw: [EXTERNAL] Follow up on Hall B Halo Rates Troubleshooting

[Michael Tiefenback]

We've had hints of scraping in 3S01 and vicinity.  It may be useful to test the sensitivity of 2R vertical (perhaps horizontal as well) steering.  The orbit locks steer the beam in the accelerator with some delay, not coordinating within the set of locks.  This flutter will move the beam by small amounts during the (very minor) steering tweaks.  If no effect on count rates is seen, then perhaps scraping is not the cause of the Hall B background rates.  Other diagnostic tests near the Hall B target are under consideration, too.

Michael Tiefenback

________________________________
From: BTeam <bteam-bounces at jlab.org> on behalf of Dennis Turner <dturner at jlab.org>
Sent: Thursday, August 27, 2020 21:03
To: HyeKyoung Park <hkpark at jlab.org>; bteam at jlab.org <bteam at jlab.org>
Subject: Re: [BTeam] Fw: [EXTERNAL] Follow up on Hall B Halo Rates Troubleshooting

Separation has already been rechecked.  First pass separation was tweaked, but no improvement for Hall B beam resulted:
https://logbooks.jlab.org/entry/3835771
https://logbooks.jlab.org/entry/3835775

Dennis

________________________________
From: BTeam <bteam-bounces at jlab.org> on behalf of HyeKyoung Park <hkpark at jlab.org>
Sent: Thursday, August 27, 2020 7:40 PM
To: bteam at jlab.org <bteam at jlab.org>
Subject: [BTeam] Fw: [EXTERNAL] Follow up on Hall B Halo Rates Troubleshooting

FYI
I presume BTeam has been pondering the results of tests and analysis.
Talk to you tomorrow,
HyeKyoung

________________________________
From: mhattawy at odu.edu <mohammad.hattawy at gmail.com>
Sent: Thursday, August 27, 2020 6:21 PM
To: Brian Freeman <bfreeman at jlab.org>; HyeKyoung Park <hkpark at jlab.org>; Stepan Stepanyan <stepanya at jlab.org>; Kuhn, Sebastian E. <skuhn at odu.edu>; Paul Vasilauskis <vasilaus at jlab.org>; Mike Spata <spata at jlab.org>
Subject: [EXTERNAL] Follow up on Hall B Halo Rates Troubleshooting

Dear HyeKyoung and all,
   Following up on the effort of understating the rates increase we see in Hall B and the logbook entry from Brian https://logbooks.jlab.org/entry/3835655. Brian reported on checking the laser phase on FC and the sensitivity to the 2C09 position. Unfortunately, we did not improve the situation and the rates are still increasing forcing me to reduce the beam current to 170 nA (from 180 nA).

Brian mentioned additional possible tests in his summary:
1. Check/ Recheck all Separation.
2. Check background relative to pre-buncher settings.
3. Test the sensitivity to Quad changes.

I would like to ask Brian if he can provide a time estimate for these additional tests and I would like to ask you if you can provide the manpower to continue this investigation tomorrow at the beginning of the day shift.

Best regards,
Mohammad Hattawy.
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