Reconstruction, June 9, 2009

Time: 11:00 EST/10:00 CST

• • Ventrilo for sound. (Zisis will connect) See GlueX Communications for detailed instructions
• ESNET Number 8542553

Reconstruction To Do List

1. Generation
   1. Use genr8 for a2 production
   2. Skim off (hd_filter) the wanted events by cutting on the total neutral energy (> 6 GeV) but record the total number of events before skimming. The resulting MC data set will be stored for general use.
   3. Use Pythia for background generation after removing a₂ → η π⁰ from the MC data stream as well as events with total neutral energy <= 6GeV.
   4. Use a2 charge exchange production xsection vs pythia total xsection to estimate number of signal and noise events 124μb @ 9GeV ?
2. Analysis
   1. After pruning the Pythia events, check the generated vs. reconstructed energy in a plot.
   2. Look at the a2 mass peak - adjust cuts on the eta and pi0 masses then look at the effect on the different angular distributions (i.e. Gottfried-Jackson angles, etc.)
   3. look at difference between reconstructed and generated z position for less than 65 cm
   4. look at single photon reconstruction efficiencies
   5. adjust the error matrix for the BCAL (look in PID/DPhoton_factory.cc)
3. Gather all relevant DocDB documents and cross section publications at one spot on the Wiki.

Documents to Review

• Reconstruction References

1. Gluex-doc-856
2. GlueX Calorimeter Review Feb 2008

Tentative Agenda

1. Review Reconstruction Plans in list above
2. a2_1320
   1. η's and π0's are not separate objects (as much as I understand) that I can apply cuts to when looking at the 4 photon invariant mass in the current code. The η doesn't know that I also made a π0.
   2. proton reconstruction is now included via HDParSim
3. bggen and Pythia
   1. HOW-TO:
      • bggen: by default uses the photon beam spectra over 0.15 to 12 GeV. Cross-section??. This has to be modified in fort.15 to 9GeV for us to compare cross sections. This also now dramatically increases our background data set by a factor of 10 over the default beam energy. Why is there a limit on 2.2 million events?
      • filter_HighE: Filter out events with total neutral energy less than 6GeV.
      • hdgeant: run the background thrown data set through hdGeant.
      • fCalTree: reconstruction of possible pi0s and etas. η's and π0's are not separate objects
4. Discussion on Analysis

a2(1320) analysis

Above:reconstructed energy ratio as a function generated energy

Above:Photon multiplicity

Above: invariant mass distribution selecting events with only 4 reconstructed photons

pythia background

Above: photon energy fraction as a function of Thrown energy. Full of Fail.

Above: Pythia photon multiplicity after neutral energy filtering and reconstruction.

Above: invariant mass distribution selecting events with only 4 reconstructed photons from Pythia background.