2009.08.24 Test of corrected EEMC geometry

Test of corrected EEMC geometry (bug 1618)

Monte-Carlo setup:

• One particle per event (photons, electrons, and pions)
• Full STAR 2006 geometry.
  In Kumac file: detp geom y2006g; gexec $STAR_LIB/geometry.so
• Flat in eta (1.08-2.0), phi (0,2pi), and pt (3-30 GeV)
• Using A2Emaker to get reconstructed Tower/SMD energy (no EEMC SlowSimulator in chain)
  what assumes fixed sampling fraction of 0.05 (5%)

Some definitions:

• Et correction factor : average p_T^thrown / E_T^{reco}.
  E_T^{reco} is the total energy in the Endcap Calorimeter (from A2Emaker)
• Sampling fraction: average 0.05 * Energy^{reco} / Energy^thrown.
• SMD energy: average energy in all strips fired (u-plane used for this post)
• Number of SMD strips fired: average total number of strips fired (u-plane used for this post)

Notations used in the plots:

• Left plots: no cAir fix
• Right plots: cAir-fixed
• Photons: black
• Electrons: red
• Pions: green

Et correction

Note: compare "Left" plots with Brians old results

Figure 1a: Et correction factor vs. pt thrown

Figure 1b: Et correction factor vs. eta thrown

Figure 1c: Et correction factor vs. phi thrown

Sampling fraction

Note: compare "Right" plots with Jason results with EEMC only geometry

Figure 2a: Sampling fraction vs. pt thrown

Figure 2b: Sampling fraction vs. energy thrown

Figure 2c: Sampling fraction vs. eta thrown

Figure 2d: Sampling fraction vs. phi thrown

SMD energy

Figure 3a: SMD energy vs. energy thrown

Figure 3b: SMD energy vs. eta thrown

Number of SMD strips fired

Figure 4a: Number of SMD strips fired vs. energy thrown

Figure 4b: Number of SMD strips fired vs. eta thrown

2009.08.25 Test of corrected EEMC geometry: shower shapes

Test of corrected EEMC geometry (bug 1618)

Monte-Carlo setup is desribed here

• One particle per event (photons, electrons, and pions)
• Full STAR 2006 geometry.
  In Kumac file: detp geom y2006g; gexec $STAR_LIB/geometry.so
• Flat in eta (1.08-2.0), phi (0,2pi), and pt (3-30 GeV)
• Using A2Emaker to get reconstructed Tower/SMD energy (no EEMC SlowSimulator in chain)
  what assumes fixed sampling fraction of 0.05 (5%)
• Vertex z=0
• ~50K/per particle type
• Non-zero energy: 3 sigma above pedestal

Figure 1:Single photon shower shape before (red) and after (black) EEMC cAir bug fixed
pt=7-8GeV, eta=1.2-1.4 (left), eta=1.6-1.8 (right)

Figure 2: Single photon shower shape vs. data
Monte-Carlo: pt=7-10GeV, eta=1.6-1.8
data: no pre-shower1,2; pt_photon>7, pt_jet>5. no eta cuts.
(see Fig. 1 from here for other pre-shower conditions)

2009.08.27 fixed EEMC geometry: pre-shower sorted shower shapes & eta-meson comparison

Test of corrected EEMC geometry: shower shapes (bug 1618)

Monte-Carlo setup is desribed here

• One particle per event (photons, electrons, and pions)
• Full STAR 2006 geometry.
  In Kumac file: detp geom y2006g; gexec $STAR_LIB/geometry.so
• Flat in eta (1.08-2.0), phi (0,2pi), and pt (3-30 GeV)
• Using A2Emaker to get reconstructed Tower/SMD energy (no EEMC SlowSimulator in chain)
  what assumes fixed sampling fraction of 0.05 (5%)
• Vertex z=0
• ~50K/per particle type
• Non-zero energy: 3 sigma above pedestal

Color coding:

• Black - photon (single particle/event MC)
• Red - electron (single particle/event MC)
• Green - neutral pion (single particle/event MC)
• Blue - photons from eta-meson decay (real data)

Single particle shower shape before (left) and after (right) EEMC cAir bug fixed
Single particle kinematic cuts: pt=7-8GeV, eta=1.2-1.4
Eta-meson shower shapes (blue) taken from Fig. 1 from here of this post
All shapes are normalized to 1 at peak (central strip).

Figure 1: Pre-shower bin 0: E_pre1=0; E_pre2=0

Figure 2: Pre-shower bin 1: E_pre1=0; E_pre2>0

Figure 3: Pre-shower bin 2: E_pre1>0; E_pre1<0.004

Figure 4: Pre-shower bin 3: E_pre1>0.004; E_pre1<0.01

Shower shape ratios

Results only for corrected EEMC geometry
All shapes are divided by MC single-photon shower shape.

Figure 5a: Pre-shower bin 0: E_pre1=0; E_pre2=0

Figure 5b: Pre-shower bin 1: E_pre1=0; E_pre2>0

Figure 5c: Pre-shower bin 2: E_pre1>0; E_pre1<0.004

Figure 5d: Pre-shower bin 3: E_pre1>0.004; E_pre1<0.01

Figure 6: Single photon to eta-meson shape ratios only (with error bars):
Pre-shower bins 0 (upper-left),1 (upper-right),2 (lower-left), and 3 (lower-right)

Extracting gamma-jet cross section at forward rapidity from pp@200GeV collisions

Analysis overview

1. Data samples, event selection, luminosity determination
2. Isolating photon-jet events
   • Transverse shower shape analysis
   • Isolation cuts
   • Cut optimization
3. Trigger effects study
4. Data to Monte-Carlo comparison/normalization and raw yields
5. Acceptance/efficiency corrections
6. Corrected yields
7. Background subtraction
8. Systematic uncertainties
9. Comparison with theory

Data samples, event selection, luminosity determination

Real data, and signal/background Monte-Carlo samples:

• pp@200GeV collisions, STAR produnctionLong.
  Trigger: eemc-http-mb-L2gamma [id:137641] (L ~ 3.164 pb^1)

• Pythia prompt photon (signal) Monte-Carlo sample.
  Filtered Prompt Photon p6410EemcGammaFilter.
  Partonic pt range 2-25 GeV.

• Pythia 2->2 hard QCD processes (background) Monte-Carlo sample.
  Filtered QCD p6410EemcGammaFilter.
  Partonic pt range 2-25 GeV.

Isolating photon-jet events

1. Shower shape analysis
   • Shower shapes
   • Sided residual analysis
2. Isolation cuts
   • Energy clustering (2x1 vs. 2x2 vs. 3x3, cluster energy vs. rapidity)
   • Charge particle veto
   • photon and jet pt balance
   • Tower multiplicity
3. Cut optimization with LDA.
   Input variables (list can be expanded):
   • Energy fraction in 3x3 cluster within a r=0.7 radius, E_3x3/E_0.7
   • Photon-jet pt balance, [pt_gamma-pt_jet]/pt_gamma
   • Number of charge tracks within r=0.7 around gamma candidate
   • Number of Endcap towers fired within r=0.7 around gamma candidate
   • Number of Barrel towers fired within r=0.7 around gamma candidate
   • Shower shape analysis: distance to 80% cut line
   • Energy fraction in E_2x1 and E_2x2 witin E_3x3
   • Energy in post-shower layer under 3x3 tower patch
   • Tower energy in 3x3 patch
   • SMD-u/v energy in 25 central strips
   • SMD-u/v peak energy (in 5 central strips)

Trigger effects study

No studies yet

• Trigger effects vs pt
• Trigger effects vs eta
• What else?

Data to Monte-Carlo comparison/normalization and raw yields

• Overall data to MC normalization based on vertex z distribution
• Data to MC comparison of raw yield in various detector subsystems
• Uncorrected yields optimized with different efficiency/purity

Acceptance/efficiency corrections

No studies yet

• What needs to be studied for acceptance/efficiency effects?
• Converting reconstructed photon (jet) energy/momentum to the true one
• Reconstruction efficiency vs. rapidity, pt, etc

Corrected yields

No studies yet

• Produce acceptance/efficiency corrected yields

Background subtraction

No studies yet

• Statistical background subtraction based on Pythia+GEANT Monte-Carlo
• Estimate systematic uncertainties due to background subtraction

Systematic uncertainties

No studies yet

• Calorimeter energy resolution
• Trigger bias
• Other effects

Comparison with theory

No comparison yet

• Request for pQCD calculations at forward rapidity