Feasibility Studies of Low-mass Mesons Identification for the CBM Project Radoslaw Karabowicz Hot Matter Physics Department, Institute of Physics, Jagiellonian University

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Feasibility Studies of Low-mass Mesons
Identification for the CBM ProjectRadoslaw
KarabowiczHot Matter Physics Department,Institut
e of Physics, Jagiellonian University
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entered the CBM project on Nov.15, 2002 and
consists of Jerzy Cibor, Zbigniew Majka, Pawel
Staszel, Pawel Szostak, R. K.
Krakows group in the CBM collaboration
Tools -UrQmd event generator (104 central
AuAu events _at_ 25 GeV/u) -Pluto event
generator (106 light vector mesons
decays) -Geant4 transport code (simulation of
the detector)
Goals -Find expected working conditions of
the silicon tracking detector (hit densities,
radiation dose) -Assess the possibility of
detection of light vector mesons via ee- decay
channel
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CBM experiment and STS
Silicon Tracking Stations Magnet Target Beam pipe
Compressed Baryonic Matter
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Light vector mesons in central AuAu collisions
at 25 GeV/u
particle particles/event ee- br. ratio
w 10 7.1510-5
r 10 4.4810-5
f 1 3.0010-4
and w?p0 ee Dalitz decay channel 5.9010-4
Particle multiplicities NALL 1582 NCH 944
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Signal and background comparison
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Hit densities
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Collision rate, radiation Vector damage

• in numbers
• about 107 AuAu collisions per second,
• multiplicity of charged particles will be about
  103 in central AuAu collision (on average
  250),
• the inner parts of the first silicon tracking
  station will be exposed to about 107hits per mm2
  per second, that is 1012hits/mm2/week,
• radiation damages in the Si detector
  (displacement of atoms in the crystal lattice)
  was calculated for inner parts of the first STS
  the displacement damage cross section D exceeds
  60 MeVmb in one central event (per week D ? 1013
  MeVmb)
• A. Vasilescu (INPE Bucharest) and G. Lindstroem
  (University of Hamburg), displacement damage in
  silicon, on-line compilation.

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Extraction of the ee signal from light vector
mesons decays
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In progress

• magnetic field tracking
• investigation and optimization of different cuts
• realistic detector efficiencies,
  misidentifications