Difference between revisions of "Kinematic Fitting of Two Photon Decays"

From GlueXWiki
Jump to: navigation, search
Line 1: Line 1:
Procedure:
+
===Procedure===
  
 
* generate 1 GeV η's which decay generically in the GlueX detector
 
* generate 1 GeV η's which decay generically in the GlueX detector
Line 9: Line 9:
  
  
Results:
+
===Results===
  
 
The plots below show confidence level and two photon invariant mass for four types of fits:
 
The plots below show confidence level and two photon invariant mass for four types of fits:

Revision as of 12:45, 4 September 2007

Procedure

  • generate 1 GeV η's which decay generically in the GlueX detector
  • reconstruct η→γγ and π0→γγ
    • π0 produced in η decay have low momentum
    • very few additional "clean-up" cuts applied
  • kinematically fit η's and π0's and examine confidence level distributions and pull distributions.
    • tests the accuracy of the photon covariance matrix


Results

The plots below show confidence level and two photon invariant mass for four types of fits:

  • π0 fit with two photons in the FCAL
  • π0 fit with two photons in the BCAL
  • η fit with two photons in the FCAL
  • η fit with two photons in the BCAL

Combinatoric backgrounds produce a peak at low confidence level and tails away from the nominal two-photon invariant mass. The relatively flat confidence level distribution is an indication that photon covariance matrices are properly constructed.

Two gam fit.jpg