[BTeam] 7S01 BLM trips

[Brian Freeman]

All,

So, upon setting up the machine we "tried" adjusting the 1st step in 1S and 2S, per our new cold start up procedure. What we were missing was the 2nd large common dipole in the second step in pass 2, this process remains in development and untouched from design.

Per Jay's survey, and his conclusions we may need to adjust the S/R angles into the East Arc(s). Options could include a change back to design in the 1st step. From my observations it was not a large change in the overall optics, so could be something we try?

Another possibility is that the bleed though from the A and C beams are being plowed into the BS dipoles and creating the Radiation signature. Adjusting the angles from the YR and the ZA may help, especially since there was a warm region in the YR.  However, if it is the bleed through being lost in the BS dipoles, the "problem" with 7S trips may remain. Just want to throw this out there as a possibility, and ask has anyone looked into bleed through?

-Brian


________________________________
From: BTeam <bteam-bounces at jlab.org> on behalf of Jay Benesch <benesch at jlab.org>
Sent: Monday, October 25, 2021 1:23 PM
To: BTeam <bteam at jlab.org>; mcc_ops at jlab.org <mcc_ops at jlab.org>
Subject: [BTeam] 7S01 BLM trips

Colleagues,

I did a moderately detailed rad survey of the NE spreader, staying
outside the rope around MYBBS06.  I provide my conclusions in
https://logbooks.jlab.org/entry/3932262

To summarize: beam is bent upwards less than design in the common
dipoles.  The 7S ZA and 9S YR are at design.  MYBBS04 was at design
before it shorted and MYBBS06 was very hot.  The 7S01 BLM is above the
entrance to MYBBS06 so the trips were appropriate.

Since we don't want to mess with the BCOMs, I suggest steering to
address the 7S01 BLM trips be confined to the 9S YR and 7S ZA, in that
order because the beam pipe is cool entering the YR and hot exiting it.

YMMV

Jay
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