[BTeam] B-Team Meeting to discuss new schedule

[Brian Freeman]

Joe,

The dipole field maps for Arc 1 and Arc 2 have already been updated to include the anticipated error, so the expectation is that we are closer than before (others please correct me if I am wrong).  We are planning on sending beam into Hall A 1st pass for the energy calibration ahead of the spin dance to hopefully get a better idea of energy discrepancies. I think that this will help? Beam into Hall possibly by Friday next week for energy measurement, if all goes well, if of course Hall A is still okay with this.

Thanks,
-Brian

________________________________
From: BTeam <bteam-bounces at jlab.org> on behalf of Joe Grames <grames at jlab.org>
Sent: Wednesday, November 13, 2019 10:28 PM
To: Yves Roblin <roblin at jlab.org>; bteam at jlab.org <bteam at jlab.org>
Cc: Simona Malace <simona at jlab.org>; Javier Gomez <gomez at jlab.org>; Stepan Stepanyan <stepanya at jlab.org>; Dave Gaskell <gaskelld at jlab.org>
Subject: Re: [BTeam] B-Team Meeting to discuss new schedule

Mike, Brian - please include Simona, Stepan, Dave in your scheduling discussions, since their support is required to validate the machine energy viz a viz the spin dance.

Since the purpose of this early spin dance is to belt and suspenders how precisely we set the machine energy, then it seems we ought to complete it prior to starting physics, right?  Your attached schedule shows Halls B/D starting physics on 11/25, before the spin dance on 11/27.

That said, the spin dance is going to yield one of three cases:

  1.  nailed it => great, move on...
  2.  good enough => w/ A longitudinal, Halls B&C say polarization is close enough => great, move on...
  3.  not good enough => w/ A longitudinal, Physics requests a machine energy adjustment to satisfy B&C

In case #3 have you already agreed how to react?   I imagined the response would be to use the Hall B or C spin dance data to inform a <0.1% adjustment to the linac energies.   Why like this?   In broad stroke, each ~10 deg correction at 5-pass incurs ~1 deg change at 1-pass.   For example, changing machine energy to correct 20 deg error at 5-pass incurs ~2 deg change at 1-pass, or thereabouts.   When you then fix 1-pass with the Wien to satisfy longitudinal polarization then 5-pass is now only "wrong" by ~2 deg, not 20 deg, which is tolerable, i.e. cos(2)~0.999 vs. cos(20)~0.940.   That's the high level argument I have in mind.

I have a conference call + meeting Friday 1-3pm, so glad to discuss any of this before or after the b-team mtg,
Joe

________________________________
From: BTeam <bteam-bounces at jlab.org> on behalf of Yves Roblin <roblin at jlab.org>
Sent: Wednesday, November 13, 2019 6:14 PM
To: bteam at jlab.org <bteam at jlab.org>
Subject: [BTeam] Fwd: B-Team Meeting to discuss new schedule





Sent from my Verizon, Samsung Galaxy smartphone

>From Camille Ginsburg:


Dear Colleagues,

Let's have a special B-Team meeting Friday 15.Nov. at 1pm in the MCC conference room to discuss the new schedule Mike A. and Brian put together (please see attachment).  The goal is to check that the re-start schedule is as accurate as possible, and check whether anything can be run in parallel or otherwise optimized so we can get to physics sooner.  Clearly we must not compromise the quality of necessary work.  By Monday I will give the experimenters our estimate for the physics start delay.

If you have a related Atlis, please be sure to attend or send a representative.

Thanks,
Camille

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