minutes of GEn01 meeting (June 18, 2003)

From: Glen Warren (gwarren_at_anti-spam)
Date: 19-Jun-2003 11:42:36


GEn01 analysis meeting June 18, 2003
====================================

attended by:
    Paul, Oscar  at UVa
    Hongguo, Frank, Nikolai and Glen at JLab

REPORTS

*) Background: Frank has completed binning of background for Q2=1, 4th 
pass.  The overall correction is 0.5%.  We discussed the uncertainty, 
and decided to go with the sigma of the distribution of background over 
the various runs.  It is almost certainly an overestimate, but at 0.2%, 
it will have no practical impact.

*) CEX: Frank has several questions about Marko's CEX number, mostly 
concerned with exactly how to apply the corrections.  Frank has sent 
Marko an email and is waiting for a response.

*) uncertainty in dilution factor: Hongguo compared the rates for 
different target materials as provided by Nikolai.  Hongguo was 
concerned about the ratio of the proton to neutron rates varying for the 
different targets.  Nikolai commented that this ratio is very clean, so 
it is probably related to physics.

There is about a 20% scaling factor between data and MC (data is 
larger).  Hongguo followed the procedures set out for Q=0.5, and gets an 
uncertainty of 2.6% in the stick 4 dilution factor.

*) Target polarization: Paul investigated the spike in new times for run 
around 73 minutes.  He found that for Q2=1, there are the distribution 
of the length of the runs spikes around 70-75 minutes.  Next, he looked 
at individual runs, and found that indeed there is a spike in runs 
around 73 minutes, but once you look on a scale of seconds instead of 
minutes, you see differences.  Glen is satisfied that everything the 
spike is real.  Paul will submit version 9 of the target polarization list.

*) paper: no progress.

*) model uncertainties: There was a long discussion about the model 
uncertainties.  Nikolai raised the issue that the inclusion of the model 
uncertainties as Glen proposed may double count errors.  The discussion 
made several circles.  Glen, Hongguo, Frank and Nikolai will met on 
Friday to reach some conclusions.

*) Combining stick 3 and Stick 4: We will take the average.  The 
question is how to do the average.  We agreed to use sqrt(counts) as the 
weighting, i.e. <f> = (sqrt(N_3)f_3+sqrt(N_4)f_4) / (sqrt(N_3)+sqrt(N_4))



Donal
        *) work on paper.
        *) review surveyors reports are target alignment

Glen
        *) work on paper
        *) Lead discussion on model uncertainties, kinematic 
uncertainties, etc.


Frank
        *) accidentals
        *) complete Q2=0.5 replay
        *) incorporate CEX correction

Hongguo
        *) kinematic uncertainties

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