Difference between revisions of "FCAL Reconstruction 04/08/2012"

Revision as of 22:19, 8 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.

E_raw/E_thrown plots

Check for theta dependence (currently not accounted for):

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Only apparent at low angles near hole in FCAL.

Dependence on number of blocks

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