Ilya Selyuzhenkov December 08, 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)

Detector subsystems involved in analysis:

1. TPC (vertex, jets, charge particle veto)
2. Endcap EMC (triggering, photon candidate reconstruction)
3. Barrel EMC (away side jet reconstruction)

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)

Figure 1: EEMC x vs. y position of photon candidate for 2008 data sample
Problem with pre-shower layer in Sector 10 can been seen in the upper left corner

Figure 2: EEMC x vs. y position of photon candidate for 2006 data sample

Figure 3: Average < E_pre1 * E_pre2 > for 3x3 cluster around high tower
vs run number for sectors 9, 10 and 11
Note, zero pre-shower energy for sector 10 (black points) for days 61, 62, 64, and 67.
All di-jet events for pp2008 data are shown (no gamma-jet cuts)

Figure 3a: Same as Fig.3, zoom into day 61

Figure 3b: Same as Fig.3, zoom into day 62
Figure 3c: Same as Fig.3, zoom into day 64
Figure 3d: Same as Fig.3, zoom into day 67

Figure 4: EEMC x vs. y position of photon candidate for 2008 data sample
Same as Fig. 1, but excluding days: 61, 62, 64, and 67

Conclusion on QA:

No problem with pp2008 data have been found,
except that for some runs (mostly on days 61, 62, 64, and 67)
EEMC pre-shower layer for sector 10 was off.

Comparison between 2006 and 2008 data

Figure 5: 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 6: Shower shapes within +/- 30 strips from high strip (same cuts as in Fig. 5):

Figure 7: Shower shapes within +/- 5 strips from high strip
(same cuts as in Fig. 5, no scaling):