2009.12.07 Low EM study: LOW_EM option, 100KeV cuts, and DCUTE=100KeV

Conclusions/dicsussion at the emc2 hypernew
http://www.star.bnl.gov/HyperNews-star/get/emc2/3369.html
http://www.star.bnl.gov/HyperNews-star/get/emc2/3375.html

Monte-Carlo setup:

  • Throwing one photon per event
  • Full STAR y2006h (latest EEMC, v6.1 and TPC, v04 geometries)
  • Throw particles flat in eta (1.08, 2.0), phi (0, 2pi), and energy (5-35 GeV)
  • Using A2Emaker to get reconstructed Tower/SMD energy (no EEMC SlowSimulator in chain)
  • Vertex z=0
  • ~50K/per particle type
  • Non-zero energy: 3 sigma above pedestal

GEANT EM cuts list (default values in GeV)

  • CUTGAM - cut for gammas (GEANT default = 0.001)
  • CUTELE - cut for electrons (GEANT default = 0.001)
  • CUTHAD - cut for charged hadrons (GEANT default = 0.01)
  • CUTNEU - cut for neutral hadrons (GEANT default = 0.01)
  • CUTMUO - cut for muons (GEANT default = 0.01)
  • BCUTE - cut for electron brems (GEANT default = CUTGAM)
  • BCUTM - cut for muon brems (GEANT default = CUTGAM)
  • DCUTE - cut for electron delta-rays (GEANT default = 10^4)
  • DCUTM - cut for muon delta-rays (GEANT default = 10^4)
  • LOSS - energy loss
  • STRA - energy fluctuation model
  • Birks law parameters (Tracking Parameters)
    MODEL BIRK1; RKB BIRK2; C BIRK3

Low EM cut configurations (values in GeV)

  1. NoCuts: Default STAR geometry EM cuts

    Endcap EMC setup is quite non-uniform
    (all cuts are set via "Call GSTPAR (ag_imed,'CutName', Value)":

    • Block EMGT: 30 degree megatile

      CUTGAM = 0.00001
      CUTELE = 0.00001

    • Block ESCI: active scintillator (polystyrene) layer

      CUTGAM = 0.00008
      CUTELE = 0.001
      BCUTE = 0.0001
      CUTNEU = 0.001
      CUTHAD = 0.001
      CUTMUO = 0.001
      c-- Define Birks law parameters
      BIRK1 = 1.
      BIRK2 = 0.013
      BIRK3 = 9.6E-6

    • Block ELED : lead absorber plate

      CUTGAM = 0.00008
      CUTELE = 0.001
      BCUTE = 0.0001
      CUTNEU = 0.001
      CUTHAD = 0.001
      CUTMUO = 0.001

    • Block EALP: thin aluminium plate in calorimeter cell

      CUTGAM = 0.00001
      CUTELE = 0.00001
      LOSS = 1.
      STRA = 1.

    • Block EHMS: defines the triangular SMD strips

      CUTGAM = 0.00008
      CUTELE = 0.001
      BCUTE = 0.0001
      c-- Define Birks law parameters
      BIRK1 = 1.
      BIRK2 = 0.0130
      BIRK3 = 9.6E-6

  2. 100KeV: All cuts are set to 100KeV

    CUTGAM = 0.0001
    CUTELE = 0.0001
    BCUTE = 0.0001
    BCUTM = 0.0001
    DCUTE = 0.0001
    DCUTM = 0.0001

  3. DCUTE: All cuts are set to 10KeV, except electron delta-rays (DCUTE = 100KeV)

    CUTGAM = 0.00001
    CUTELE = 0.00001
    BCUTE = 0.00001
    BCUTM = 0.00001
    DCUTE = 0.0001
    DCUTM = 0.00001

  4. LOW_EM: All cuts are set to 10KeV

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

Figure 1: Endcap EMC sampling fraction for different cluster sizes:
1x1, 2x1, 3x3, and total energy in the EEMC
Lower right plot shows total s.f. vs. photon thrown energy

Figure 2: Endcap EMC shower shapes

Figure 3: Endcap EMC shower shape ratios