[d2n-analysis-talk] BB cer peds

[Brad Sawatzky]

On Fri, 19 Feb 2010, posik at jlab.org wrote:

> I have looked at the ped values from the runs that I showed in our
> meeting yesterday
> 
> https://hallaweb.jlab.org/wiki/images/0/04/Posik_20100217.pdf
[ . . . ]
> Looking at these plots I don't think that our peds will be shifting
> from run to run.

Those do look fairly stable.  That's good, at least.

> I also fitted a run 1314, a 13uA run on the v792 ADC. Those fits can
> be seen here:
> 
> http://jlab.org/~posik/d2n/BB/cer/peds/ped_values/1314_beam_ped_values_2.png
> 
> If this looks ok, I will start to enter these new ped values into the
> DB files.

OK.  Note that you will need to confirm that the pedestals in the DB are
correct (and stable) for every configuration change.  This includes:
  - significant beam current changes 
    - ie. any low-current calibration/optics/efficiency-check runs with
      I_beam < 8uA should also have their pedestals confirmed/updated
  - BB Cerenkov HV changes
  - 1881 vs. v792 switch-over
  - amplifier vs. no amplifier changes
  - changes/repairs to the 60Hz filters on the ADC
  - the period when (some) Cerenkov signals were split and fed into an
    FADC and an 1881/v792

You should also document these checks by generating histos of the
pedestals for runs associated with the above changes and putting them in
an appropriately named folder (or PDF file, etc) along with sufficient
notes so that you can figure out what was done 6 months from now.

-- Brad

-- 
Brad Sawatzky, PhD <brads at jlab.org>  -<>-  Jefferson Lab / Hall C / C111
  Ph: 757-269-5947 -<>- Pager: 757-584-5947 -<>- Fax: 757-269-7848
The most exciting phrase to hear in science, the one that heralds new
  discoveries, is not "Eureka!" but "That's funny..."   -- Isaac Asimov