Notes from Local Meeting on Oct. 22, 2003

General Updates

• Introduction of Hachemi Benaoum, a graduate student from Syracuse. Tentatively will work on Lumi and HAPPEX-Pb.
• No new rumors on HAPPEX-H/He Startup.
• Eugene Chudakov has a start on the GEANT simulation to model Septum Heating.
• We would like an update on the status of the Small Angle Lumi Monitor installation.
• Meeting for the HAPPEX-I paper tomorrow (10/23/03)

Individual Updates

• Maud

  • New photo-cathode from SVT. It's a strained superlattice developed at SLAC. A different type of doping should provide for higher Quantum Efficiency (QE) without a limit on current.
  • Slides shown on QE, Polarization, Analyzing Power, and Conclusions from recent studies in the Test Cave. (PPT, PostScript)
  • This cathode provides the possibility of running with a diode laser during HAPPEX. However, Compton background may be quite sensitive to the ON/OFF transition of the diode laser.

• Lisa

  • Studies of LaserMetrics Cell have revealed that it is unusable for HAPPEX. It deflects the laser beam due to the wedge on the cell and imperfectly matched index matching fluid between the cell windows and cell.
  • Studies of TX Cell are on hold until the new switch arrives.
  • The cell used during the April Injector Studies may be studied further in the laser room, if G0 opts to use a different cell when they run. This cell is currently in the tunnel.
  • A polarimeter has been obtained, and will be used to characterize wave-plates (RWP, etc.). First impressions is that it is not very stable as a measuring tool.
  • Studies on imaging using the Ti-Saph laser are still ongoing.

• Bryan

  • Linearity Studies of HAPPEX PMTs with the HAPPEX ADCs have slowed due to signal ringing and large leakage currents. Probable culprits: conductivity between PMT base ground and HV dinodes, and improper matching of the PMT base load resistor with the HAPPEX ADC input impedance.
  • Demonstration of a beta version of an Online GUI to be used to view histograms and ROOT Tree variables. A version of this will be used for HyperNuclei (which will use the new Hall-A C++ analyzer) and will be compatible with PAN for use during HAPPEX-H/He/Pb.

• Tim

  • Still studying current bleedthrough during Small Angle GDH. Looking at correlations with Hall-C beam, slit widths, etc..

• Ryan

  • Helping in the Laser Room.
  • Beginning the analysis of position differences and charge asymmetry during Small Angle GDH.

• David L.

  • Working on the imbedded LED in the detector assembly to aid in linearity studies.
  • Considering a switch for swapping between HAPPEX DAQ to Event by Event DAQ. Old switch used during HAPPEX-I was noisy. An amplifier may be required to boost the PMT signals for the Event by Event DAQ.
  • Working on the proposal for the Compton Upgrade

• Kent

  • Working in the Laser Room.

• Bob

  • Preparing for HyperNuclei