[Sbs] [EXTERNAL] Physics impact of modifications to the SBS magnet on upcoming program?

[Bogdan Wojtsekhowski]

Hi Brad,

The bypass of flat slabs coils were planned for GMn/GEn due to stray field on BB detectors. The plan now is to use 2100 A with 4 flat slabs as now considered, when needed, which provides 1.60 Tm.

Bogdan


________________________________
From: Brad Sawatzky <brads at jlab.org>
Sent: Friday, October 29, 2021 3:57 PM
To: Robin Wines <wines at jlab.org>; Jessie Butler <jbutler at jlab.org>; Bogdan Wojtsekhowski <bogdanw at jlab.org>; Andrew Puckett <puckett at jlab.org>; Arun Tadepalli <arunts at jlab.org>; David Hamilton <dhamilto at jlab.org>; Michael Kohl <kohlm at jlab.org>
Cc: sbs at jlab.org <sbs at jlab.org>
Subject: [EXTERNAL] Physics impact of modifications to the SBS magnet on upcoming program?

Hi folks,

I thought about asking these during today's RC meeting, but decided
it might be easier to get better answers on the list.

I gather 6 of 10 of the SBS racetrack coils will be bypassed and, at
least in the near term, the magnet will be run at a lower current.

How does this impact the field uniformity (within the acceptance)
and the integrated BdL of SBS?  Is the lower SBS current (1600A?)
intended to be a maximum for this run period (I wasn't sure how to
interpret that discussion).

I believe GEn-RP assumed a BdL of 1.7 T.m at a nominal 2000A.  It
would be good to know well in advance if those assumptions need to
be reworked.


Other important mechanical/engineering items that need to be reviewed
with Jessie and Robin (et al.) include:

- Status and plans for the beamline shielding 'wall' that sits between
  SBS and the beamline and will need to be installed along with the
  GEn-RP detectors.

- Installation and possible mechanical interferences with the SBS
  Rear Field Clamp.
  - This is not presently installed but will need to be installed with
    the GEn-RP detectors.
  - As it stands the new braces between SBS and the beamline corrector
    magnets appear incompatible with the SBS rear field clamp.

- Magnetic forces on the (steel) passive analyzer plate.
  - I know this has been raised several times in the past, but given the
    recent excitement those calculations should probably be reviewed.

-- Brad

--
Brad Sawatzky (he/him), PhD <brads at jlab.org> -<>- Jefferson Lab/ Hall C/C111
Ph: 757-269-5947  -<>-  Fax: 757-269-5235  -<>- Pager: brads-page at jlab.org
The most exciting phrase to hear in science, the one that heralds new
  discoveries, is not "Eureka!" but "That's funny..."   -- Isaac Asimov
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