Karl Slifer discussed the Scintillator efficiency correction:

• Checked the error contribution to the cross section
• Scintillator efficiency degraded over time
• Check on each energy:  error below 0.5% in each

    Karl looked at the difference in the Left and Right arm cross sections:

Studied temperature dependence of the density
• Temperature difference in the RTD values for Armageddon
         in parallel and transverse configurations (laser power?)
• Variation of n_t with T_p about 1% in 10 degrees
• Found file: rtd.bak, reproduced Steffen's temperature
        correction fairly well.
• Ioannis gave Karl updated target chamber densities, which
        have a 1% difference from Steffen's thesis
• Unpolarized cross section systematic error:  2.3% on fill density,
        2.0% final error on temperature corrected densities
• Question about increasing the number due to the large standard
        deviation and uncertainty of T_p (Delta = 34 +/- 18)
• Not an issue for error on cross section due to factor of P_tn_t

• Exclude runs at very low nu
• Compare data with Seonho's analysis
• For electron arm, parallel configuration agrees well, and
        perpendicular has a few points within error bars
• JP noted that the 5 points after the pion threshold are lower than
        Seonho's analysis (excluded runs?)
• Suggestion that Seonho and Karl should choose the same runs
• Hadron arm both analyses have similar results
• Note:  Difference in 50 MeV binning of Karl and Seonho's results

Issues since the last meeting:
• Ready to publish at the end of 2001, except for a few issues
• Big difference in asymmetries of two arms for perpendicular
        configuration at 3.4 GeV
• Strange shape of (sigma)^tt near pion threshold at 862 MeV
• Narrow width for Delta at 1.7 GeV


Problem with Helicity dependent deadtime corrections:

• Corrections not applied correctly
• Big corrections for some kinematic regions
• Small change for perpendicular configurations, except
        862 MeV QE region
• Fixes a few hard to solve problems
• Increases GDH integral by ~ 50% at lowest Q2


Helicity dependent deadtime corrections:

• Not beam trips
• Closely related to high deadtime (Disk write activity)
• Removal of high deadtime period reduces the corrections
• Asymmetry also changes, so final corrected values are stable


Strange shape of (sigma)^tt:

• Shape is due to data from perpendicular configuration
• The behavior is in both arms
• RC generate diverging features

    Seonho presented his conclusions:

• Helicity dependent deadtime correction properly applied
• Need to study the error on the perpendicular cross
        section at 862 MeV
• Ready for publication

• Karl will look at the bug in rebinning from 10 to 50 MeV
• Seonho will work on the systematic error in the DT correction
• Look at the difference in perpendicular and parallel cross sections

Problem:
• Rising tails at high nu, which cannot be explained by
        elastic tails from N₂ and ³He
• Additional material thickness ruled out by elastic and QE
        study
• Present for different targets and energies
• Seems to be unpolarized


Alexandre looked at contamination from windows due to straggling:
 

• Contamination cannot be cut with software cuts
• Two types:  events at large forward angles (1.15 to 3 degrees)
        and events close to HRS
• Determined that the second type of events are negligible
        (20 ppm for P0 = 250 MeV)
• The first type of events could be dominant, analysis has large
        uncertainties due to unmeasured cross sections at low Q²
• Need a more sophisticated simulation and check


Other issues:

• Results sensitive to beam and target parameters
• Using an upper value for the parameters, the tail can
        be increased in size by 4.5 order of magnitude
• Another possibility is a large photon flux, need to check
• Is this an issue for Small angle GDH?  Target diameter smaller, but
        no data taken at low momentum and beam quality is better
• Precautions:  take empty target run at low P0, and positron runs at
        low momentum (if it is a possible candidate)

Conclusions:

• Identified a few processes that could produce a rising tail
        at low momentum
• Need more work to give reasonable estimate
• Check photon flux candidate
• Issue for E97110?

    Work to be done for GDH:

• Finish checks for first PRL, see above, and change the
        error bar on the GDH curve so it is less confusing
• Begin work on second paper
• Preliminary decision on which figures to put in paper
• Figure 1 has a plot of g₁ and g₂ for ³He Vs. W²
        for the six energies
• Figure 2 has a plot of g₁ and g₂ for ³He Vs. x
        at 6 values of constant Q²
• Figure 3 will have Gamma-1, Gamma(p-n),
        Gammaⁿ₂, dⁿ₂ Vs. Q²
• Discussion on to add a table with g₁ and g₂ at different
        Q².  Need a Decision on whether to cite a web page or preprint
• Zein-Eddine will have something for the second paper
        a week before the next collaboration meeting
• Nilanga offered to work on a third paper discussing duality
        and higher moments