Compton Meeting, June 4, 2013 (L210A)

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Agenda

Usual meeting room (L210A).

Miscellaneous

• Collaboration meeting coming up. Note from Mark Pitt:

This will be an important meeting.  We will be carefully assessing our
progress to determine how realistic our goal of putting forward an April
2014 invited talk nomination by the deadline of October is (the final
decision would be made at our October collaboration meeting).

Laser

• Haven't started measurements, but PC is working and filters have arrived.

Photon Detector

• Look at backgrounds via scalers - correlate with extracted asymmetries.
• Certifying the Monte Carlo
  • I would like to generate a "status summary" including what has been changed from Megan's version and what we think is wrong at the moment. ELOG 262
  • I would also like to generate a concrete job list.

Electron detector

• Efficiencies from tracking mode data (accounting for angle of electrons on detector)
  • Efficiency from straight tracks: Edet log 532
• Effect of efficiency (at trigger level) on extracted polarization
  • Elog from last week: Edet log 531 --> need more statistics to get reasonable error estimate

Minutes

• Collaboration meeting: Will Qweak want to show results from Run-1 + Run-2 at April 2014 APS meeting? DG wrote to Mark Pitt - answer is yes. But if Run-1 is not ready, they can live with just Run-2. We should mention and discuss at July collaboration meeting.

• Electron detector
  • Discussion of Amrendra's MC efficiency tests. Statistics now large enough that unc. calculation makes some sense. Efficiency has 0.04% effect (max.) on polarization. This is for spectra with good statistics - what happens when errors are more comparable to what we get for a good run in the experiment?
  • To explore this, we may need to run the MC in "experiment" mode in which each helicity state is explicitly generated (rather than calculating the weighted average of the analyzing power). This takes a lot more CPU time.
  • Running the MC this way may also be required to explore noise and cross-talk.
  • Discussed Vladas' update of his earlier log entry exploring efficiency from tracking data. As he looks at the tracks, it appears that the strip that is hit in each plane is changing in the opposite order than expected. For example, rather than hitting strips 44-45-46 in planes 1-2-3, the strip order is 46-45-44. This implies some kind of (vertical) offset of the planes.
• Photon detector
  • Juan Carlos shows list of changes made to Megan's GEANT4 simulation. It is important that each one of these changes be compared to the un-modified (or minimally modified) version of her simulation to make sure we have a solid benchmark for our extracted analyzing powers.