Seq. Number
(TBA   ) 
Research Plan at RIKEN CC-J  
                                Date:   17/09/03   (DD/MM/YY) 
 
To: the Planning and Coordination Office of RIKEN CC-J 
 
Reseach Subject : Direct photon mesurement in RHIC-PHENIX 
 
(PHENIX official or not :      no ) 
 
Person responsible for this research: 
Name : Takuma Horaguchi 
Tel/Fax : 1-631-344-2256/1-631-344-7158 
E-mail : horaguchi@bnl.gov 
 
Person responsible for the job submission: 
Name : Yasuyuki Akiba 
Tel/Fax :  
E-mail : akiba@rhic.rcf.bnl.gov 

Person responsible for the job submission: 
Name : Takuma Horaguchi 
Tel/Fax : 1-631-344-2256/1-631-344-7158 
E-mail : horaguchi@bnl.gov 
 
Other collabrators in this research subject: 
Name : 
tel/Fax: 
E-mai: 
   
 
Summary of this research (10-100 lines) 
 
We need disk space in CCJ because of starting the direct photon  
analysis at CCJ. The direct photon events is very interesting for  
us bucause of the following reason ; 
 
1, Measurement of the gluon distribution function (g(x)) in proton 
2, Provide a testing ground for precision perturbative QCD 
3, Baseline for future polarized pp collision analysis for polarized
   gluon distribution function (delta g(x)) 
 
We are going to carry over this analysis as the following procudure. 
At first, we have to estimate the background from photons in Jet and
charged particles and so on. The number of them is much bigger than  
the direct photon events. Therefore, it is important to estimate the
background for selecting the direct photon events. We request  
"isolation cut" for selecting direct photon candidates. The "isolation
cut" means that the photon is isolated other photon or charged particles. 
Additionally, we reconstruct pi0 and eta which two photons from thier
decay are detected and evaluate the ratio between the yield that both 
photons are accepted and the yield that one of the two photons is not 
accepted. 
Secondaly, we will calculate the cross section of direct photon. 
To calculate the cross section, we need to estimate of efficiency of
isolation cut because of suppressing the bremssstlugling process by  
isolation cut. We will estimate by using Monte Carlo simulation (PYTHIA)  
and PISA simulation program.   
 
For these estimation, we need disk space and CPU time as following.  
 
   
Estimated CPU time required : 10000 hours (with Pentium III 1GHz) 
   
Estimated disk space usage required :  200 GB 
  
Estimated HPSS space usage required :  200 GB 
 
HPSS band width for above estimate  :  12 MB/s 
 
Target date for completion :   31/12/03   (DD/MM/YY) 
 
Plan for the publication of this result (if possible) 
 
CC-H Home  



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