[b1_ana] draft proposal

[O. A. Rondon]

Hi JP,

J. P. Chen wrote:
> 2) For charge determination, it is confusing. Should not say 5%. With the
> calibration of Tungsten calorimeter, the BCM will have an absolute
> uncertainty
> at the level of 1-2%, and relative uncertainty (from one target
> polarization period
> to next period) should be better than 1%, depending on the linearity of the
> BCM response.
> 

We need to be careful here. Since this is a Hall C proposal, Dave Mack
will tell you that he cannot calibrate the low current BCM's to better
than 5% (5 nA at 100 nA). See this hclog entry
https://hallcweb.jlab.org/hclog/0902_archive/090211140308.html

I think the 1% estimate is reasonable, but it involves integrating over
time. I believe the charge monitors read every 2s in Hall C. So we'll
have to accumulate about 25 readings, or one minute, for a 1% delta Q/Q.

I'm sure the Hall A calorimeter will help, but how long does it need to
integrate at 100 nA for a 1% error?

In any case, we need to be precise about this for the TAC.

Cheers,

Oscar