Ilya Selyuzhenkov December 09, 2008

Data sets:

• pp2006 - STAR 2006 pp longitudinal data (~ 3.164 pb^1)
  Trigger: eemc-http-mb-L2gamma [id:137641]
• pp2008 - STAR 2008 pp data
  Trigger: etot-mb-l2 [id:7]
  Days: 53-70; ~0.5M triggered events (1/3 of available statistics)

Gamma-jet analysis cuts:

1. Select only di-jet events
2. cos(phi_gamma - phi_jet) < -0.8 : gamma-jet opposite in phi
3. R_EM^jet < 0.9 : neutral energy fraction cut for the away side jet
4. N_ch=0 : no charge tracks associated with a gamma candidate
5. N_bTow = 0 : no barrel towers associated with a gamma candidate (gamma in the endcap)
6. N_(5-strip cluster)^u > 2 : minimum number of strips in EEMC SMD u-plane cluster around peak
7. N_(5-strip cluster)^v > 2 : minimum number of strips in EEMC SMD v-plane cluster around peak
8. gamma-algo fail : my algorithm failed to match tower with SMD uv-intersection, etc...
9. Tow:SMD match : SMD uv-intersection has a tower which is not in a 3x3 cluster
10. R_{3x3cluster}: Energy in 3x3 cluster of EEMC tower to the total jet energy (not applied here)

Comparison between 2006 and 2008 data

Figure 1: Vertex z distribution:
All gamma-jet cuts applied, plus pt_gamma>7 and pt_jet > 5 GeV (exlcuding days 61, 62, 64, and 67)
Results are shown for pp2008 data sample (black), vs. pp2006 data (red).
pp2008 data scaled to the same total number of candidates as in pp2006 data.

Figure 2: Shower shapes within +/- 30 strips from high strip (same cuts as in Fig. 1):

Figure 3: Shower shapes within +/- 5 strips from high strip
(same cuts as in Fig. 1, no scaling):