[BTeam] NL gradient calibration results

[Nathan Rider]

We are planning  on replacing the RF module at 1A21 and 1A26 during the maintenance day tomorrow.  If the North Linac was open we could change the RF module at 1A04 as well.  The A04 stack has been very problematic and we cannot guarantee that replacing the RF module would fix it.  However, it would give us some valuable data and there is a chance it will fix the issue.

--Nate
________________________________
From: Jay Benesch <benesch at jlab.org>
Sent: Tuesday, November 28, 2023 10:29 AM
To: BTeam <bteam at jlab.org>; Christopher Slominski <cjs at jlab.org>; Adam Carpenter <adamc at jlab.org>; Nathan Rider <nrider at jlab.org>; Dave Gaskell <gaskelld at jlab.org>
Subject: NL gradient calibration results

Colleagues,

The spreadsheet attached has the results of the rfcal run taken of the
entire NL in order over ten hours with 1E-3 energy lock offset and
comparison with data taken with somewhat different conditions earlier
that day and the previous day - see comments column.

The 11/16 data beginning 1545 was taken with
IPM1A04 2.51 m etax
IPM1A21 7.59 m etax
IPM1A26 -2.39 m etax
either disabled or excluded from BEM

The earlier data was taken with IPM1A26 included.

All of the SL data was taken with all BPMs active.  The sum of the
calibrated momentum gains was 1037.3 MeV vs 1047 MeV per the arc.

In the NL, without these three BPMs, the sum is 1180 MeV, 12.7% above
1047.  I conclude that BEM's calculation and therefore the energy lock
is not accurate without at least 1A21 and perhaps all three BPMs.  This
may explain why the polarization has been off expected values in all
halls and why HALLC:p is 20 MeV below that expected from eDT.

Jay



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