Meeting Info.

Meeting Time

9:00 EST

We meet via Skype. The relevant Skype user names are:

some phone numbers if needed:

David: (757) 269-5567 Rory: (413) 545-2480

Attendees: Rory M. (chair), David L., Sascha M.

Contacted Richard Jones about beam polarization optimization. Received long e-mail in response with lots of info.
FOM to optimize polarization will include polarization^2 times event rate
Need to get correlation between polarization and energy from Richard
Still considering a relative measurement where we normalize to the π^o cross-section rather than try measuring the absolute photon flux.
- Photon flux was largest contributor to error bar in PrimEx in Hall-B
- Hall-D has very long distance between radiator and target and a collimator, making it difficult or impossible to use the tagger for photon flux measurement
- Pair spectrometer is option, but may not be as precise as π^o cross-section measurement.
- Further study is required
We are still missing the azimuthal distribution of the ππ system (not in Elton's plots)

Reproduced plots shown by Sascha last time of π⁺ energy with and without secondaries turned on
- Plots were somewhat consistent, but overall much cleaner than what Sashca saw. Most likely due to a newer version of the Hall-D sim-recon code.
Plot of efficiency vs. z-location of target produced using JLab farm
Vertex-constraint left on, but the z-location of the constraint was left at z=65cm (i.e. did not match the vertex location) This was an over site
Will re-reun with vertex-constraint off and also with it on, but adjusted to match vertex location

Look at π^o cross-section as a function of energy for potential use as normalization reaction (Rory)
Get correlation between polarization and energy from Richard (Rory)
Update sim-recon version and re-run to confirm Dave's plots (Sascha)
Re-run z-vertex scan with vertex constraint off as well as on, but aligned with vertex (David)