Heavy Ion Photon reconstruction

Complete: 3

Goal of this page

The aim of this page is to document the photon reconstruction used in heavy ion events, where the code lives, how to run it, the input and output, and details of the implementation.

Code and tags

The code lives in the package RecoHI/HiEgammaAlgos.

The most recent version of the code will be tagged in CMSSW_3_4_0_pre4.

Before CMSSW_3_4_x release, if you want to check out the latest working version yourself, you can check out the release by the following command:

scramv1 project CMSSW CMSSW_3_3_0
cd CMSSW_3_3_0/src
cvs co -r V00-00-06 RecoHI/HiEgammaAlgos

and compile:

scramv1 b

This will prepare the working environment for you.

Configuration files

Compared to the p+p photon reconstruction algorithm, the photon reconstruction in Heavyion collision use Island SuperCluster algorithms for both barrel and endcap regions while in p+p one uses the hybrid algorithm for the barrel and multi5x5 algorithm for the endcap. This choice is found to cache less background contribution compared to hybrid and multi5x5 algorithm.

The reconstruction sequence is defined in RecoHI/HiEgammaAlgos/python/HiEgamma_cff.py.

Also the primary vertex for photon reconstruction is taken from heavyion algorithm.

How to run the photon reconstruction

Do you need to run the photon reconstruction?

If you already run the heavyion reconstruction, you don't need to do it yourself.

Running the photon reconstruction only

Running the full heavy ion reconstruction


Parameter settings


Photon ID / Isolation cuts

Heavy ion specific photon ID / Isolation variables are stored as user variable in PAT::Photon, while p+p default photon ID and isolation are also stored for comparisons / studies.

Accessing the heavy ion photons isolation variable


Responsible: YenJieLee

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Topic revision: r4 - 2009-11-09 - YenJieLee
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