# 9/25/2006 Group Meeting 1 Measuring bremsstrahlung photons in pp collisions Ali Hanks Group Meeting Sep. 25, 2006.

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9/25/2006 Group Meeting 1 Measuring bremsstrahlung photons in pp collisions Ali Hanks Group Meeting Sep. 25, 2006

9/25/2006 Group Meeting 2 Outline/Methodology Method: select  dir associated with high p T hadron using correlations 1 st Step: construct hadron-  inc correlation functions 2 nd Step: remove background from decay photons –construct hadron-  tagged correlations from  0 decays –estimate tagging efficiency as a function of  and p T using fastmc –use corrected hadron-   0 to estimate the total hadron-  dec contribution 3 rd Step: calculate  frag yield from resulting h-  dir correlation

9/25/2006 Group Meeting 3 h-  inc per trigger yield

9/25/2006 Group Meeting 4 h-  tagged per trigger yield + fg  tagged + bg  tagged

9/25/2006 Group Meeting 5 h-  tagged per trigger yield With combinatorial background subtracted

9/25/2006 Group Meeting 6 h-  subtracted per trigger yield h-  inc – h-  tagged as a first try at subtracting decay contribution

9/25/2006 Group Meeting 7 Tagging efficiency +  inc + fg  tag + bg  tag +  inc +  tag

9/25/2006 Group Meeting 8 Invariant mass fg/bg + fg  tagged + bg  tagged

9/25/2006 Group Meeting 9 Tagging efficiency Simulation generates  0 s in a guassian distribution around a “trigger” hadron –distribution is p T dependant –determined from real data Let these  0 s decay and compare resulting h-  distribution for single photon acceptance and pair acceptance 00 trigger  hadron-  ∆  distribution ∆∆ single acc pair acc

9/25/2006 Group Meeting 10 Tagging efficiency estimates Study tagging efficiency as a function of  in several p T bins Still need to do this with input  0 spectrum from pp and run 5 acceptance Tagging efficiency 4 < p T < 4.5 GeV/c ∆∆ Tagging efficiency p T > 6 GeV/c ∆∆ Tagging efficiency p T < 3.5 GeV/c ∆∆

9/25/2006 Group Meeting 11 To Do Complete work on subtraction of h-  decay –errors in calculation of combinatorial background for tagging  0 decay photons –esitmate of tagging efficiency using fastmc still in early stages –contribution from other hadronic decays Still not clear if shape is same as for   0

9/25/2006 Group Meeting 12 Hot tower Maps hot towers for cluster with p T from 1-2 GeV/c

9/25/2006 Group Meeting 13 Hot tower Maps hot towers for cluster with p T from 2-3 GeV/c

9/25/2006 Group Meeting 14 Hot tower Maps hot towers for cluster with p T from 3-20 GeV/c

9/25/2006 Group Meeting 15 Backup – tagging efficiency Input  0 distribution with gaussian around trigger larger than acceptance

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