[halla_compton] Hall A Compton meetings Wednesday and Thursday

[Mark-Macrae Dalton]

Hi all,

These are my memories of what we discussed at the meeting.

We discussed the possibility of flipping the laser helicity.  Dave’s model was based on significantly more data taken in this state so it was thought prudent to leave it in the more well known state.  We discussed taking Compton data to do a systematic check of laser polarization.
* After the Wien flip, Dave et al will take data with the laser polarization set to an off-maximum value to compare the drop in asymmetry with the laser polarization model.
This should be about a shift on either side of the maximum polarization (current running).  If all goes well, this could be done on Friday.

We discussed the Compton spectra.  The most recent target out run does not appear to be well fit by the simulation which makes the analyzing power uncertain.  We desire to center the beam on the collimator as soon as possible to decrease sensitivity.  We also discussed the idea of removing the collimator.
* Amali will make some changes to fitting of spectra to investigate the disagreement.
  ** Fit only the high energy ~half of the Compton spectrum but plot the fit over the full range.  Do not include a pedestal offset in the fit.
 (Already done see: https://hallaweb.jlab.org/dvcslog/compton/524)
* Make an access at the earliest reasonable opportunity to lower the snapshot threshold to try and take a better target-out spectrum.

We discussed accumulator 0 results.  There are non-statistical fluctuations in the minirun results.  The leading hypotheses was thought to be varying backgrounds which are not we accounted for in the current ~10 minute background subtraction procedure.
* Juan Carlos will resurrect the cycle-wise analysis code and hand it off to Adam.  Now that we have a behaving laser this is a better analysis algorithm.
* Adam will make plots of the asymmetry at various timescales: cycle-wise, run-wise, and slug-wise

We briefly discussed accumulator 4.  Juan-Carlos said that he will look into this when he comes off RC.

Please let me know if you have any corrections or additions.

Regards,
Mark





On Aug 21, 2019, at 10:03 AM, Dave Gaskell <gaskelld at jlab.org<mailto:gaskelld at jlab.org>> wrote:

Hi all -

Reminder that we will be meeting at 11 am in room F226.

Cheers,
Dave

On 8/20/19 4:56 PM, Dave Gaskell wrote:
Hi everyone -

There will be a couple Hall A Compton meetings in the next couple days.

The first will be tomorrow (Wednesday, August 21) at 11 am EDT - this meeting will focus on the Compton status and data from the ongoing run.  The agenda is on the wiki:

https://hallaweb.jlab.org/wiki/index.php/Wednesday,_August_21,_2019,_11:00_am_EDT

Those on site can meet in room F226, Bluejeans link: https://bluejeans.com/140287970

The second meeting will be Thursday (August 22), also at 11 am EDT. The focus of this meeting will be to discuss plans for installing and testing the electron detector for the upcoming CREX run.  This meeting will also be in room F226, with the same Bluejeans connection.

Regards,
Dave

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