Introduction

Our long-term goal in the photon analysis group is to perform an A_LL measurement with photon+jet events.  Right now highly-developed code exists for jet trees and for gamma trees, but there is no maker for gamma+jet together.  I sent an email to the phana mailing list looking to find what people had done.  The thread starts here.  I'll update what I'm working on in this blog page.

Progress

1.  Make some photon+jet trees for a day of data to play with.  Runs are from good run list in 2006:

#Run      Fill                                     QA Note

7136022 7863 ppProductionLong        Ok
7136023 7863 ppProductionLong        Ok
7136024 7863 ppProductionLong        Ok
7136027 7863 ppProductionLong        Ok
7136031 7863 ppProductionLong        Ok
7136033 7863 ppProductionLong        Ok
7136035 7863 ppProductionLong        Ok
7136041 7863 ppProductionLong        Ok
7136045 7863 ppProductionLong        Ok
7136046 7863 ppProductionLong        Ok
7136073 7864 ppProductionLong        Ok
7136075 7864 ppProductionLong        Ok
7136076 7864 ppProductionLong        Ok
7136079 7864 ppProductionLong        Ok
7136080 7864 ppProductionLong        Ok
7136084 7864 ppProductionLong        Ok

I used the script the Robert Fersch wrote for testing earlier this year as my starting point.  I made some changes to try to make it more condor-friendly.  Also had to do 2 changes to make it run:

i.  Add gSystem->Load("StJetEvent") before gSystem->Load("StJetMaker);

ii.  Change gammaMaker->setSmdRange(20.0); to gammaMaker->setBsmdRange(20.0) and gammaMaker->setEsmdRange(20.0)

I am considering adding the endcap pi0 maker to this chain as well, but one thing at a time.

2. Port Renee's code to fresh cvs co of jet code.  Just did a diff between files and added the getGamma() and gammaHisto() functions to the StRoot/StJetMaker/StJetReader code.  Compiles.

3.  Cross fingers and run Renee's code.  I had to load some extra libraries on both the jet and gamma side (note: someone with karma should fix loadGammaLibs() to load libMinuit()).  Also Renee had verifyJet as an assert, which I just changed to skip the jet.  Otherwise if the assert fails on the first event then you will miss everything else in that run.

4.  Stripped out unused parts of StJetReader in Renee's code and moved it to a new class "StBetaPhoJetMaker" so that I can use the most recent jet code and avoid having a private copy.  Should get rid of StJetReader redundancies so it's bare minimum of what I need.  Then plan to look at some tree making functionality (see Pibero's code for this).