PID in the CBM by TOF

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PID in the CBM by TOF
CBM Collaboration meeting, February 11-13,
2004 GSI, Darmstadt

• D.Kresan, I.Kadenko, O.Bezshyyko, V.Pluyko,
  V.Shevchenko

Taras Shevchenko National University of
Kyiv Ukraine
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Outgoal

• Hadron identification with TOF
• Impact of non-perfect PID on D0 detection
• Radiation damages in the STS

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PID by TOF
Efficiency of K? identification as a function of
momentum
TOF wall to be placed at 10 or 15 m ?
parameters time resolution
80 or 60 ps track length resolution 4
mm momentum relative uncert. 6.4e-3
purity 50
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PID results
10m RPC improvement gives roughly the same
resolution, with smaller losses in low momentum
15m wall better resolution, but higher decay
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PID results (2)
Identification probability as a function of polar
angle
pt slope 151MeV ?y 0.85
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K- acceptance
STS
STSTOF
laboratory momentum distribution
STSTOFPID 10m, 80ps
transverse momentum vs. rapidity
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D0 significance
STS standart setup TOF 10m
considering ltD0gt10-3, ?m18MeV, non-perfect
PID 3? detection limit
Nev4.7e6 S/B2
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D0 significance (2)
STS standart setup TOF 15m
considering ltD0gt10-3, ?m18MeV, non-perfect
PID 3? detection limit
Nev4.1e6 S/B2.4
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Background at 10 GeV/u
y01.53 ? T122 MeV ?y0.922 K- T142
MeV ?y0.802
Transverse momentum and rapidity distributions of
K- and ?
748 background pairs per event
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D0 significance at 10GeV/u
STS standart setup TOF 10m
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D0 significance at 10GeV/u (2)
STS standart setup TOF 15m
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Radiation damages in the STS

• Total Ionizing Dose
• Displacement damages

Calculation of equivalent dose rate and 1MeV
neutron flux for first two stations
Particle fluxes from central AuAu collision _at_
25AGeV reaction rates 10MHz
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TID in the STS
Energy losses of charged particles in first
station z5cm, d500?m UrQMD Geant4
Quality factor vs. specific energy losses in water
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Eq. dose rate distribution
z5cm
worst pixel 0.68 Sv/s
z10cm
worst pixel 0.45 Sv/s
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Displacement damage
Kinetic energy of particles, produced in one
event UrQMD Geant4
Hardness parameter vs. kinetic energy
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Eq. neutron flux density
z5cm
worst pixel 7e9 n/s?cm2
z10cm
worst pixel 2.4e9 n/s ?cm2
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Displacement effects
Taken from preparation to InIn run by NA60
collaboration
n doped
p doped
M.Keil, Effects of Radiation Damage in the NA60
Silicon Pixel Detectors
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Displacement effects (2)
For the silicon pixel telescope from
NA60 considering estimated fluxes for the CBM
experiment
At maximum rapidity type conversion after 4?109
events.
Depletion voltage ?250V after 7?1010 events.
But still depleted pixels at midrapidity
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Conclusion and next steps

• D0 significance was calculated with non-perfect
  PID
• Estimated radiation damages can be used in
  selection of right candidate for STS
• TODO
• Increasing of statistics in pointing angle
  distribution for background at 10GeV/u
• Measurements of radiation damages effects on
  pixel detectors (after making choice)