[Primexd] [EXTERNAL] run plan note

[Alexander Somov]

Hi Matt and Ashot,

My apologies for the late response, I was busy in the tagger hall.

This is a good point, we have to have enough data to refine the FCAL
calibration with the magnet on data. According to Igal, an  8-10-hour long
run will provide enough statistics to do this. We are currently planning to take
beam on data  for several shifts (we need to discuss it more during the meeting).

Thanks for bringing this up.

Cheers,
              Sasha






________________________________
From: Shepherd, Matthew
Sent: Tuesday, August 24, 2021 12:47 PM
To: Ashot Gasparian
Cc: Alexander Somov; primexd at jlab.org
Subject: Re: [Primexd] [EXTERNAL] run plan note


Hi Ashot,

> On Aug 24, 2021, at 11:11 AM, gasparan at jlab.org wrote:
>
> Will it be possible to measure that with the existing light
> monitoring system?
> This, of course, assumes that the LMS does not change significantly
> from the magnetic field.

It might be possible, but as you state there are some assumptions.  Also the inner blocks are  most difficult to illuminate with the LMS and these are the ones you care about most.  Even if you use the LMS I don't think it will remove the need for an independent calibration of the "field on" data.

Of course we've taken data with field off and on and apparently the effect isn't dramatic.  We see the HV setpoints for production GlueX running is largely consistent with choices/gains for PrimEx running with field on.

I just don't know the the effect has been quantified at the level that is needed for your analysis.

Matt

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