Difference between revisions of "FCAL Reconstruction in b1pi events 03/06/2012"
(→Efficiency) |
(→Extra photon problem) |
||
| Line 53: | Line 53: | ||
* The match radius is hardcoded as 5 cm, but in the calib/PID/photon_track_matching this parameter is set to 15 cm. Change this back to 15 cm. | * The match radius is hardcoded as 5 cm, but in the calib/PID/photon_track_matching this parameter is set to 15 cm. Change this back to 15 cm. | ||
| − | THE TIMING CUT WAS ALREADY IN EFFECT FOR THE PLOTS ABOVE... FIX THIS | + | THE TIMING CUT WAS ALREADY IN EFFECT FOR THE PLOTS ABOVE... FIX THIS... FIXED |
Revision as of 20:19, 6 March 2012
Contents
Thrown photons
Reconstructed photons
(after vetoing cluster matched to charged tracks)
Questions
- Why are so many "photons" reconstructed? How can we reduce this?
- What is the actual reconstruction efficiency?
- How many photons reach the FCAL without converting?
- Efficiency for non-converting photons?
- Can we recover converted photons?
- Energy resolution, etc.
1 GeV photon events
Mihajlo in GlueX-doc-823 (2007) says for 1 GeV photons:
- 99.6% efficiency for photons that reach FCAL
- 37% photon conversion before FCAL
- Taking into account single clusters from photons that converted close to the FCAL face, the overall photon reconstruction efficiency was estimated to be 77%
- 4% energy resolution at 1 GeV
Has anything changed since 2007? How does b1pi sample differ from single photon sample?
Efficiency
Energy distribution of thrown photons:
- Black=all thrown photons
- Red=photons which reach the FCAL without converting (determined using DFCALTruthShower object)
- Blue=photons which reach the FCAL without converting AND are reconstructed successfully (fabs(theta_thrown - theta_recon) < .004 && fabs(phi_thrown - phi_recon) < .08)
Red/Black=% of photons that reach FCAL without converting:
Roughly 20% of photons convert before reaching FCAL. Relatively constant across wide range of energy. There is an angular dependence, not shown here. Big improvement since 2007 (geometry change?)
Blue/Red=
Above 1 GeV, 98.6% of uncoverted photons are reconstructed. This is less than the 99.6% reported for single photon sample, most likely this difference is due to photon shower overlapping with charged particle shower.
Below ~600 MeV, efficiency drops. This is due to showers contained within a single cell, which means no cluster is created.
Overall FCAL reconstruction efficiency considering only uncoverted photons: 72%. Could be higher after trying to recover photons that convert.
Extra photon problem
To reduce number of extra "photons", consider a more aggressive matching of clusters to charged tracks:
- Only one matching FCAL cluster per track is allowed with the current code. Frequently hadronic showers are grouped into multiple clusters.
- The match radius is hardcoded as 5 cm, but in the calib/PID/photon_track_matching this parameter is set to 15 cm. Change this back to 15 cm.
THE TIMING CUT WAS ALREADY IN EFFECT FOR THE PLOTS ABOVE... FIX THIS... FIXED
