Zero Degree and Very Forward Calorimeters for the CBM experiment

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Zero Degree and Very Forward Calorimeters for the
CBM experiment
Alexey Kurepin Institute for Nuclear
Research, Russian Academy of Science 117312
Moscow, Russia

• 5.11.2004 CBM-Russia meeting, ITEP, Moscow

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Weizsacker-Williams method of equivalent quanta
Enrico Fermi 1924 äquivalente strahlung

C.F. Weizsacker and E.J. Williams
1930s relativistic case
Projectile
Z
P2
Equivalent pulses of radiation

Target
Target
P1
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Forward emission of neutrons RELDIS predictions
Most of the neutrons are emitted with Pt lt 0.15
GeV/c - much lower compared to hadronic
interactions !
Our detectors at H8 beam line are well suited to
detect EMD neutrons !
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Schematic view of experimental setup for forward
neutron emission measurements for 30 A GeV Pb
ions _at_ CERN SPS
S0, S1, SS plastic scintillator detectors.
MBPL and MBPL - Magnets
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Energy resolution and response as function of the
beam coordinate
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Calorimeter response and relative energy
resolution as a function of the pion beam energy
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Energy spectra of the neutron calorimeter in
proton and Pb runs
1n
ADC spectrum for 30 GeV protons
2n
3n
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Sum of 1n and 2n cross sections is well described
by RELDIS
Target RELDIS Experiment
Al 0.64 0.64/-0.05
Cu 3.03 3.2/-0.2
Sn 8.62 10.8/-0.7
Pb 21.52 21.9/-1.6
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Calculated and measured 1n and 2n emission in
dissociation of 30GeV Pb ion Al,Cu,Sn,and Pb
targets
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Latest ALICE-lumi dataforward neutron emission
measurements for 158 A GeV In ions _at_ CERN SPS
1n
2n
3n
4n
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Neutron calorimeter
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CASTOR PROTOTYPE
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CASTOR PROTOTYPE
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Estimations of particle density in the hole of
CBM ECAL for central UrQMD AuAu 25AGeV


estimations was done by cbmroot OCT04 gold target 250 µm Z-position 11m from target
neutrons
protons
electrons
gammas
pions
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Charmonium Feasibility studies Invariant mass
spectra for signal (J/?) di-electron
combinatorial background normalized to 1 event.
J/?
J/?
35 AGeV
25 AGeV

• Background source
• UrQMD central AuAu events with beam energy 25,
  35 AGeV
• electrons efficiency 90
• momentum resolution 1
• all electrons with vertex closer than 1 cm to
  target (very pessimistic estimation)
• and Ptgt1GeV/c was included into background
• pion suppression factor was 10-4
• electrons selected on the TRD3 (Z815cm)

• Simulation conditions
• CBMROOT Geant3 transport
• Homogeneous magnetic field used in simulation
• Dielectron decay of J/? was calculated by PLUTO