Difference between revisions of "FCAL Reconstruction 04/08/2012"
(→FCAL energy corrections) |
(→E_raw/E_thrown plots) |
||
| Line 47: | Line 47: | ||
Check for theta dependence (currently not accounted for): | Check for theta dependence (currently not accounted for): | ||
| − | [[]] | + | [[File:SinglePhotonFCAL.ratio 2D n blocks.svn8951.png]] |
Only apparent at low angles near hole in FCAL. | Only apparent at low angles near hole in FCAL. | ||
| Line 53: | Line 53: | ||
Dependence on number of blocks | Dependence on number of blocks | ||
| − | [[]] | + | [[File:SinglePhotonFCAL.ratio 2D theta.svn8951.png]] |
Revision as of 10:56, 9 April 2012
Efficiency
There is a tunable parameter in the FCAL code with default:
MIN_CLUSTER_BLOCK_COUNT = 2;
At lower energies (<~500 MeV), this causes photon reconstruction efficiency to be lower because often only one block has energy deposited in it (above the 20 MeV threshold in mcsmear).
In single photon sample:
- red:
MIN_CLUSTER_BLOCK_COUNT = 1 - black:
MIN_CLUSTER_BLOCK_COUNT = 2
In b1pi events:
- Overall FCAL efficiency increases by ~6%: 78% -> 84%
- 15% in total photon count (after timing cut) (1.18->1.36)
1-block "clusters" will collect less energy than multi-block clusters of same photon energy-->will affect energy calibration, energy resolution
Energy resolution
- red:
MIN_CLUSTER_BLOCK_COUNT = 1 - black:
MIN_CLUSTER_BLOCK_COUNT = 2
Fit to black curve says sigma(E) = 6.1%/sqrt(E) ⊕ 1.9%
Need to recalibrate energy corrections at low E.
FCAL energy corrections
What's the deal with FCAL energy correction? current code by Mihajlo (DocDB 1093) what does this adjust for? attenuation? lack of full containment?
Assume form 
, where E_c is the energy of clustered blocks and E_gamma is the energy of thrown photon.
Fit MC data for A,B,C,
.
In reconstruction, get E_corrected from E_clust by solving this equation iteratively.
The simplest option for recalibrating would be to use the current scheme but re-fit for A,B,C, using sample with 1 block clusters. But is there a better way?
E_raw/E_thrown plots
Check for theta dependence (currently not accounted for):
Only apparent at low angles near hole in FCAL.
Dependence on number of blocks
