[d2n-analysis-talk] Gas Cerenkov Cut Efficiencies (Background Corrected)

[David Flay]

> On Thu, 11 Mar 2010, David Flay wrote:
> > The high momenta data have the largest error bars (in particular p =
> > 1.70 GeV) as we have a very short list of runs to use (I am currently
> > using all of them).
>


On Thu, Mar 11, 2010 at 10:38 PM, Brad Sawatzky <brads at jlab.org> wrote:

> Sanity check the run-list.  We spent most of our time running at the
> highest momenta.  The total statistics should be comparable to the lower
> momentum runs (this was by design).  Your "short list of runs" statement
> doesn't make sense...
>

I should've worded this better -- I meant only at p = 1.70 GeV.  There are a
plentiful supply of runs for p = 1.60 GeV.

Unless there are mislabeled runs (runs that are really 1.70 GeV, but are not
labeled as such), and I'm missing them..


> Note that you can bin all runs for a given beam energy + LHRS momentum
> setting together in order to parametrize the shape of the pion
> contamination (the LHRS just sees a pion energy distribution, and that
> energy distribution doesn't care about polarization).  You then fit that
> shape to the residual pions for each unique kinematic to get the
> associated contamination (grouping runs by polarization state too for
> this bit).
>

I'll get some more runs together for each p.



> The better question is what is the error on your fit/subtraction?  That
> is, you say your total subtraction is 2% -- a pretty small number.  Say
> your relative uncertainty on that 0.02 correction is 50%.  That sounds
> pretty bad, but in the end it is only a 1% absolute contribution to the
> error budget and that's what matters.
>

I'll take a closer look at the uncertainties in the fits.


-- 
-----------------------------------------------------------
David Flay
Physics Department
Temple University
Philadelphia, PA 19122

office: Barton Hall, BA319
phone: (215) 204-1331

e-mail: flay at jlab.org
           flay at temple.edu

website: http://www.jlab.org/~flay
             http://quarks.temple.edu
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