Test of corrected EEMC geometry: SVT and LOW_EM cuts

Monte-Carlo setup:

• One particle per event (only photons in this post)
• Full STAR 2006 geometry (with/without SVT, LOW_EM cuts)
  In Kumac file: detp geom y2006g; gexec $STAR_LIB/geometry.so (vary SVTT_OFF, LOW_EM)
  LOW_EM cut definition is given at the end of this page
• Throw particles flat in eta (1.2, 1.9), phi (0, 2pi), and pt (6-10 GeV)
• Using A2Emaker to get reconstructed Tower/SMD energy
  (this post: no EEMC SlowSimulator)
• Vertex z=0
• ~50K/per iteration
• Non-zero energy: 3 sigma above pedestal

Color coding:

• SVT, LOW_EM marked in legend as LowEM (single photon MC)
• STV, no-LOW_EM marked in legend as default (single photon MC)
• no-SVT, no-LOW_EM marked in legend as no-SVT (single photon MC)
• photon-jet candidates [pp2006] (used data points from this post)
• photons from eta-meson [pp2006]

Pre-shower bins:

1. Ep1 = Ep2 = 0 (no energy in both EEMC pre-shower layers)
2. Ep1 = 0, Ep2 > 0
3. 0 < Ep1 < 4 MeV
4. 4 < Ep1 < 10 MeV
5. Ep1 > 10 MeV
6. All pre-shower bins combined

Note: Ep1/Ep2 is the energy deposited in the 1st/2nd EEMC pre-shower layer.
For a single photon MC it is a sum over
all pre-shower tiles in the EEMC with energy of 3 sigma above pedestal.
For eta-meson/gamma-jet candidates from pp2006 data the sum is over 3x3 tower patch

Shower shapes

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: Shower shape sorted by pre-shower conditions.

Figure 2: Shower shape ratio. All shapes in Fig. 1 are divided by single photon shape
for "SVT+LOW_EM" configuration (black circles in Fig. 1)

Sampling fraction

Figure 3: Sampling fraction (0.05 * E_reco/ E_thrown)

Pre/post-shower energy and migration

Figure 4: Pre-shower1 energy (all tiles)

Figure 5: Pre-shower2 energy (all tiles)

Figure 6: Post-shower energy (all tiles)

Figure 7: Pre-shower bin photon migration

Tower energy profile

Figure 8a: Energy ratio in 2x1 to 3x3 cluster
For the first 4 pre-shower bins total yield in MC is normalized to that of the data
Blue circles indicate photon-jet candidates [pp2006] (points from this post)
Same data on a linear scale

Figure 8b: Energy ratio in 2x1 to 3x3 cluster: 7 < pt < 8 and 1.2 < eta < 1.4

Figure 8c: Energy ratio in 2x1 to 3x3 cluster: 7 < pt < 8 and 1.6 < eta < 1.8

Figure 9: Average energy ratio in 2x1 to 3x3 cluster vs. thrown energy

Figure 10: Average energy ratio in 2x1 to 3x3 cluster vs. thrown energy

LOW_EM cut definition

LOW_EM option for the STAR geometry (Low cuts on Electro-Magnetic processes)
is equivalent to the following set of GEANT cuts:

• CUTGAM=0.00001
• CUTELE=0.00001
• BCUTE =0.00001
• BCUTM =0.00001
• DCUTE =0.00001
• DCUTM =0.00001

All these values are for kinetic energy in GeV.

Cut meaning and GEANT default values:

• CUTGAM threshold for gamma transport (0.001);
• CUTELE threshold for electron and positron transport (0.001);
• BCUTE threshold for photons produced by electron bremsstrahlung (-1,);
• BCUTM threshold for photons produced by muon bremsstrahlung (-1);
• DCUTE threshold for electrons produced by electron delta-rays (-1);
• DCUTM threshold for electrons produced by muon or hadron delta-rays (-1);

Some details can be found at this link and in the GEANT manual