Simulation of

1
Simulation of Electron Identification with Fast
TRD (Fast Simulator)

• Contents
• Detector layout
• basic features starting points
• TR spectra properties (gap, foil)
• energy losses of e- ?
• ? efficiency different geometry
• summary

2
Layout of the simulated detector

• radiator (regular)
• 25 ?m Mylar foil
• gas volume (Xe/CO2)

• Standard Geometry (SG)
• 100 Polypropylene foils
• foil - 10 ?m
• gap 90 ?m
• XeCO2 (85/15), 6mm
• p 2 GeV/c (e, ?)
• 90 electron efficiency

3

• Basic features
• MC based standalone code
• microscopic simulations
• no real stuff (rate, space charge etc)
• Tuned with help of ALICE TRD simulations
  measurements ref.1
• production of the TR in the radiator ref.2
• absorption of the TR in the radiator, Mylar foil
  and gas volume
• energy losses of e and ? in the gas volume (with
  input from GEANT3)
• Likelihood distributions
• ? efficiency computation

4
ALICE TRD - Simulations Measurements

• Features
• 2GeV/c
• 4 Detectors
• 3.7 cm XeCO2 (85/15)
• PO fibres (INV6)
• momentum dependence
• not reproduced by simulation

ref. NIM A522 (2004) 40
5
TR spectrum

• SG
• ltNgt 0.8 / e
• ltEgt 8.8 keV
• ltEabgt 6.4 keV
• ltEescgt 12.5keV

6
TR properties - Foil
thicker foil more material
7
TR properties - Gap
8
TR properties Detector thickness
9
TR properties No. of foils
thicker radiator more material
10
Energy losses Likelihood
11
Energy losses Measurements Simulations
Data from testbeam July 2004, GSI
12
Pion Efficiency (I)
13
Pion Efficiency (II)
1.2
14
Summary

• What was done
• scan over basic parameters of the TR
• estimation of the Pion Efficiency for given TRD
  geometry
• 100 200 pion rejection can be reached

• What needs to be done
• more detailed simulations(rate effectsetc.)
• test the properties of such a detector in a beam
  with different radiators
• (if possible)
• concerning CBM framework digitizer..(standalone
  , or GEANT4) ..?

Ref 1 Nucl. Instrum. Meth. A519 (2004) 508 2
C.W. Fabjan et al., Phys. Lett. B 57, 483,
(1975)