Minutes for A1n Analysis Meeting, click here.
    Minutes for Small Angle GDH Meeting, click here.
    Minutes for Septum and Commissioning Meeting, click here.
    Minutes for GDH Analysis Meeting, click here.
 

    Tentative Date of next Collaboration Meeting:  May 24-25, 2002
 

    Kevin Kramer reported on the status of the g2n analysis:
 

Kevin has been conducting cut studies the past few months
• Zein-Eddine Meziani suggested that the detector calibrations
        should be checked
• In one of the plots, the windows were slightly tilted
        and needs to be corrected
• Kevin used empty cell runs to cut the windows out
• If he cuts below 16 cm from the center of the target, the percentage of
        events from the window is below 5%
• It was suggested that Kevin check the Preshower Vs. Shower plot


PID cuts:

• Kevin found no change in the asymmetries with respect to cuts
• There is only a small deviation within error bars
• Cut studies no more than 1 sigma deviation
• The group suggested that Kevin should study the effect of cutting out electrons
• The pion asymmetry walks off with cuts in the parallel configuration,
        not seen in perpendicular configurations
        (For parallel, only have 0 degree configuration)
• Question on whether or not this has statistical significance
• Suggestion that Kevin should look at one arm at a time.


Clock Synchronization and beam ramping cuts:

• Large charge asymmetry fluctuation during beam ramping
• To cut beam ramping, data events and scalers must be cut accurately
• Use ratio of scaler to event clock, but must check raw data to make
        sure no events are missing
• Issue:  Data events after scaler clock stops.  Uncertain if these are
        included in the scalers
• 10-15% of runs have these, and most are in the right arm
• For now these events are cut out, Bob Michaels has fixed the problem
        (See DAQ minutes in SAGDH minutes)
• Scaler/Event clock ratio derived from data.  Insignificant error
• Suggestion to look at individual runs with lots of beam trips
        and a few with few trips
• The charge asymmetry has a sharper peak with beam trip cuts


Raw Charge asymmetries:

• Error bars are lower for Q^2 = 0.58 configuration
• Concern over the small Chi squared for Q^2 = 0.96 parallel asymmetry
• Question on if statistics are lost, will the average stay the same?


Kevin reported the results for Xiaofeng Zhu on the QE false asymmetry:

• For no cuts, False asymmetry is 66 +/- 79 ppm
• Geometric cuts only, False asymmetry is 119 +/- 85 ppm
• Geometric and PID cuts, False asymmetry is 126 +/- 86 ppm


Issues addressed during the meeting:

• Target angle field surveys
• 4 surveys showed that the angle was within half a degree
• Last survey showed that 90 degrees was off by > 1 degree
• Conclusion that this is about the same level as the false asymmetry


Future Tasks:

• Incorporate target polarization data in asymmetries
• Perform Dead time correction accurately
• Resolve Target field direction issues
• Small corrections to cut studies (cleaner pions, slightly different PID, etc.)
• Dilution Analysis
• Elastic Data re-analysis
• Begin Looking at Radiative corrections
• Present Preliminary results at UVa/APS meetings?


Target Analysis

• For NMR, the temperature analysis is done
• Need to finish a few more details on the pressure analysis
• Working on improving the flux model
• Working to verify Sebastien's water polarization model
• For the water calibration in both channels, method to add
        the two channels in quadrature works well
• For the height Vs. flux tests, Kevin found the data fits better to
        a linear fit.  Where does the offset come from?
• Kevin studied the flux from the front of the coils fits better
        without a coefficient
• Still need to finalize polarizations from NMR for each run