06/18/2003

Small angle GDH preparation (2nd part):

• Jian-Ping:

     - septum was switched.
     - the cool down of the septum is about twice faster.
     - several sensors were added.
     - laser pipes are installed.
     - still more work needed on the beam pipe.


• Alexandre:

     - the ramping down of the septum current will be fixed.
     - showed ³He cross section assuming no ice: more checks and optics results are needed to interprete the elastic cross sections.


• Vince:

     - got all information about beam polarization from Eugene.
     - finished ice-cone water calibration.
     - recalibrated the RF field: problem to go higher RF field since the beginning of small angle GDH (ran at about 60mG).
     - Plans: field mapping and water calibration.

Spin duality analysis :(Patricia)

     - Pedestal runs analysis:
         --> unable to use ESPACE to extract all pedestal positions
         --> used pedestal files that Bob Michaels generated during the experiment.
     - Cerenkov calibration:
         --> with new pedestal values, redid Cerenkov calibration.
         --> determined gain coefficients by aligning single photo-electron peak at channel 200 (for both arm).
         --> fluctuations and incertainties in the right arm are due mostly to mirror #3 and the low statistics at 5 GeV.
     - Pion rejector (left arm):
         --> after using the new pedestal positions it looks like only 2 different calibrations will be needed (before 3 needed)
         --> still checking
     - Preshower-shower (right arm):
         --> when started to look at the PID efficiency, discovery of a big problem from the calibration that was obvious in the preshower%shower plot.
         --> the strips seen are from a bad calibration of the preshower.
         --> after several tests, I realized where my mistake was: I supposed the calibration software determined the pedestal positions.
         --> after using the new pedestal values (from pedestal run analysis) and re-running the calibration software, the preshower%shower plot looks much better.
         --> still checking and working on it.
     - Plans: finish PID calibration + efficiency, generate asymmetries.

g2n analysis :(Kevin)

     - Comparison of the internally radiated transverse polarization QE cross section with K. Griffeon calculation: what Kevin gets from Polrad and Keith calculations don't agree.

GDH analysis :(Karl)

     - going through all the steps of his analysis a last time in order to be confident in his results.