[BTeam] injector energy change this morning affected BCD

[Jay Benesch]

Mike, 

Look at figure 4 in https://logbooks.jlab.org/entry/3843977   Injector energy rose.  I didn't state that because I assumed readers would look at the elogs and because that implication of my text seemed clear to me. 

Jay 

________________________________________
From: Michael Tiefenback <tiefen at jlab.org>
Sent: Tuesday, September 8, 2020 5:20 PM
To: Matthew Bickley; Jay Benesch; BTeam
Subject: Re: [BTeam] injector energy change this morning affected BCD

It is not yet clear to me why this is in play.  Absent changes to the injection chicane BL magnets, there should have been no change in injector momentum.  The injection chicane is no longer set up in an adequately calibrated fashion (strong interferences from local dipoles in the main machine) and steering corrections are not bucked out appropriately.  If the energy in the halls fell on multi-pass beam, then it must be that the energy gain per pass fell.  With first pass energy being held constant, this must be due to a rise (not decrease) in injector energy.  I am confused by what is being stated.  Perhaps I am misinterpreting what is happening.  But it looks confused to me, although perhaps the confusion lies in a different quarter.

Michael Tiefenback

________________________________
From: BTeam <bteam-bounces at jlab.org> on behalf of Matthew Bickley <bickley at jlab.org>
Sent: Tuesday, September 8, 2020 15:33
To: Jay Benesch <benesch at jlab.org>; BTeam <bteam at jlab.org>
Subject: Re: [BTeam] injector energy change this morning affected BCD

Jay,
   Your decision is the right one...Hall A will have to live with the higher Compton counts in the interest of maintaining the other endstations' (in particular Hall C's) polarization.

Matt

________________________________
From: BTeam <bteam-bounces at jlab.org> on behalf of Jay Benesch <benesch at jlab.org>
Sent: Tuesday, September 8, 2020 3:22 PM
To: BTeam <bteam at jlab.org>
Subject: [BTeam] injector energy change this morning affected BCD

Colleagues,

https://logbooks.jlab.org/entry/3843753 Yan phased 0L04 cavities in 0L06
spectrometer
https://logbooks.jlab.org/entry/3843858 7 degree phase change needed for
A Compton counts

after phone calls from Brad:
https://logbooks.jlab.org/entry/3843974  Terry
https://logbooks.jlab.org/entry/3843977   me
https://logbooks.jlab.org/entry/3843984   me

Examining the archiver, I found that INJ:p changed by 0.87 MeV across
the injector work necessitated by the 0L04-4 problem.  This caused the
ARC1 energy lock to lower the NL by the same amount.  Hall A energy
locked by SL so it's fine.  Halls B and C lose 4*0.87 MeV and Hall D
loses 5*0.87 MeV.  This is not good for polarization in either B or C.
spinDoctor is broken on both RHEL 6 and 7 (see below) so I can't say how
bad it is.  Dave Gaskell created a graph which wmhenry posted in the
CLOG a week or so ago that showed about 1% drop per MeV.

It would seem that the only way to fix this is to go back into the
injector and adjust BL dipoles and horizontal correctors to reduce the
injector energy to where it was on owl shift.  Not something I want to
do late swing shift.  I expect I'll hear from run coordinators about my
elog and their druthers.

Jay


spinDoctor errors on RHEL6, RHEL7 roughly the same:

ACC RHEL i686 6.10 (rhel-6-ia32)
[51] benesch at opsl12 > spinDoctor&
[1] 10065
[52] benesch at opsl12 > Can't load
'/a/certified/apps/swig/cedlib/6.4/perl/5.10.1/lib/rhel-7-x86_64/cedlib.so'
for module cedlib:
/a/certified/apps/swig/cedlib/6.4/perl/5.10.1/lib/rhel-7-x86_64/cedlib.so:
wrong ELF class: ELFCLASS64 at
/usr/csite/pubtools/perl/5.10.1/lib/5.10.1/i686-linux-thread-multi/DynaLoader.pm
line 200.
  at
/a/certified/apps/swig/cedlib/6.4/perl/5.10.1/lib/rhel-7-x86_64/cedlib.pm
line 11.
Compilation failed in require at /cs/prohome/bin/spinDoctor line 25.
BEGIN failed--compilation aborted at /cs/prohome/bin/spinDoctor line 25.

[1]    Exit 2                        spinDoctor
[
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