[Hps-analysis] beam charge

[Nathan Baltzell]

Following up on the discussion in today’s meeting.  I was thinking the most
accurate way to get beam charge for cross-sections probably goes like this:

Start with the gated faraday cup scaler from its last readout in a given run, which
accounts for run duration and fluctuation in beam current and DAQ live-time.
Convert counts to charge via a calibration factor (the same one that was used to
produce the EPICS scaler_calc1 in nA).  I think Jeremy’s run summary crawler is
going to grab this for each run from the raw data and make it more accessible.

Then account for SVT position/bias “inefficiency”.  This could take the form of a
scale factor for each run with which to multiply the gated faraday cup, and it would
be the ratio of the beam current integrals from run start time to run end time for:

only when the SVT was had correct bias+position
and
everything

And this efficiency I think is what Sho has calculated and saved on the run
spreadsheet, based on data from the Mya archive.

Maybe this has all been discussed and decided on before.

Doing this for individual files is going to be more work, but I'll omit those details
for now.  May want to consider how important that is.


I think what Sebouh was showing in today's meeting was instigated because it is
currently easier and more accessible than getting the last fcup reading in each run,
but will work if he also includes HPSTRIGSC_LIVETIME in his Mya integrals to
account for DAQ livetime. 

-Nathan