Weekly Minutes 2009-10-09

   JLab:  Pawel  Ambrozewicz,  Liping  Gan,  Ashot  Gasparian,  Mark  Ito
   (chair), Victor Tarasov, Aram Teymurazyan
   UMass: Rory Miskimen

Review of items from last meeting

   We reviewed the [8]agenda from the meeting on September 25.

   Compton  results: We took a brief look at Pawel's talk from last time.
   The  next  step is a review of the analysis notes before settling on a
   final result.

Announcements

     * eta  note  from  Liping: Liping's contribution to the proceedings of
       CD2009 will be posted as a PrimEx note soon.
     * 8th  European Research Conference On "electromagnetic Interactions
       With Nucleons And Nuclei": Ashot recently returned from [10]Milos.
       He reported on several items:
          + There were workshops on electron-ion colliders and TMD's
          + COMPASS  showed  lots  of new results and plans. They see new
            states in the meson sector in the 2-4 GeV region.
          + Larry Cardman gave a report on the 12 GeV upgrade.
     * INT  Workshop  in Seattle: Next month there will be a [11]workshop
       on  12  GeV  physics  at  JLab.  Liping has been invited to give a
       presentaion on rare eta decays.


Cluster Separation Study

   Victor  presented  a  [13]study  of  the  probability of resolving two
   photons when they are close together in the HyCal. His slide presented
   the following topics:
     * Simulation of one gamma with energy 2 GeV, x=11cm y=15 cm
     * Dependence between GEANT energy and energy in HyCal
          + linear dependence is seen
     * Simulation of two gammas with energies 1 and 10 GeV; 3 and 8 GeV
     * The energy calibration in PrimEx
          + the energy correction curves shown
     * Check  of  position  and energy for 1 gamma in GEANT, energy range
       0.5 - 8 GeV, x=11 cm, y=15 cm
     * Table with values for 1 gamma simulation
     * Extreme position cases
     * A double check for 2 gammas
     * Dependence between probability to separate 2 clusters and distance
       between them
     * Conclusions

   Liping  remarked  that  the problem overlapping showers is a task left
   for collaboration.

eta Simulation Status

   Pawel showed [15]several slides describing recent progress. All showed
   properties  of  the  y signal from a helium target for three different
   detector configurations:
    1. target and tracking detectors
    2. target and no tracking detectors
    3. tracking detectors and no target

   Photons   were  detected  in  the  FCAL.  Angular  distributions  were
   generated  using  Ashot's  event  generator  for  11.3 GeV photons. He
   showed the following plots:
     * 1-d plots:
          + 2 gamma mass
          + elasticity
          + eta scattering angle
     * 2-d plots:
          + M_0 vs. theta_eta
          + invariant mass vs energy plot
          + delta-x, delta-y plot
          + cluster  position  showing  15  cm  cut  for low energy, high
            energy

   Finally he showed theta resolution for various fixed angles.

   In all cases, the magnetic field was on.

Secretary for next time

   Liping will take notes.

Next meeting time

   We will meet again in a week.

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References

   8. http://www.jlab.org/primex/wiki/index.php/PrimEx_Weekly_Meeting%2C_September_25%2C_2009
  10. http://www.iasa.gr/EINN_2009/
  11. http://www.int.washington.edu/PROGRAMS/09-3.html
  13. http://www.jlab.org/primex/weekly_meetings/slides_2009_10_09/Overlapping-clusters-in-PrimEx.pdf
  15. http://www.jlab.org/primex/weekly_meetings/slides_2009_10_09/plots.pdf