[d2n-analysis-talk] Transversity tracking efficiency report

[Brad Sawatzky]

Dec 2009 Hall A Analysis Workshop report on BB tracking:
  http://hallaweb.jlab.org/data_reduc/AnaWork2009/BigBite-Wire-Chamber-Analysis-Xin.pdf

Determine a set of good electrons _without_ using any tracking cuts
  NO cuts on momentum
  NO cuts on position, angle
  NO cuts on n_track

You should start with LHRS variables and select elastic protons.  Talk
to Zein-Eddine about what to do if you're not sure.  Suggestions
include:
  - cut on T5 only
  - LHRS: cut on elastic ToF peak
  - LHRS: cut on elastic momentum peak
  - LHRS: cut on elastic energy
  - etc,
You can do an ep elastic cross section calculation based on the proton
yield at this point and see how close you are to the known (world
average value.  Don't forget to correct for prescales, deadtime, etc.
I would think you should be able to get within a factor of 2 without
too much hassle.

Once you have a clean proton selection in the LHRS, you know (from
kinematics) that the elastic electrons are passing through BigBite.
That count is your denominator.  In ideal world, every one of those
events should leave a good track in BigBite.



This Data quality check overview from Transversity (Dec 2009 Hall A
Analysis Workshop) is also interesting (but I think I've linked to it
before).
  http://hallaweb.jlab.org/data_reduc/AnaWork2009/Transversity-Data-Quality-Chiranjib.pdf

-- Brad


-- 
Brad Sawatzky, PhD <brads at jlab.org>  -<>-  Jefferson Lab / Hall C / C111
Ph: 757-269-5947  -<>-  Fax: 757-269-5235  -<>- Pager: brads-page at jlab.org
The most exciting phrase to hear in science, the one that heralds new
  discoveries, is not "Eureka!" but "That's funny..."   -- Isaac Asimov