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RICH simulation in Geant3

RICH simulation in Geant3. Yuri Kharlov IHEP, Protvino CBM software week GSI, 10-15 May 2004. Event generators. UrQMD v1.3 as a background Au+Au at 30 GeV/nucleon b<3 fm timestamp = 40 fm/c Pluto++ v.1.60 as a signal Au+Au at 30 GeV/nucleon

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RICH simulation in Geant3

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  1. RICH simulation in Geant3 Yuri Kharlov IHEP, Protvino CBM software week GSI, 10-15 May 2004

  2. Event generators • UrQMD v1.3 as a background • Au+Au at 30 GeV/nucleon • b<3 fm • timestamp = 40 fm/c • Pluto++ v.1.60 as a signal • Au+Au at 30 GeV/nucleon • All thermal e sources from fireball decay at T=200 MeV: 0, , , 0, J/, D, D0 with appropriate weights

  3. GEANT3 model • Detector model used for simulation: • Dipole magnet 1 Tm • RICH with the shape of cut cone with a conical beam hole; front wall is 0.5-mm Al foil • RICH Cherenkov radiator is N2 at normal conditions • Spherical mirror with curvature radius 450 cm • Photodetector in the focal plane of the mirror with 100% detection efficiency

  4. 1 UrQMD event Generated events were tracked by GEANT3 with energy cut 20 MeV: pink – Cherenkov photons red – charged hadrons blue – high-energy photons green – electrons yellow – muons black – neutral hadrons Chagred hadrons give Cherenkov light at high energies only, while any electrons, even d-electrons, emit Cherenkov photons.

  5. Single particle response Number of Cherenkov photons focused onto the photodetector plane emitted by single electron of charged pion

  6. Cherenkov photon multiplicity vs hole radius (UrQMD) No beam hole: 2000 Cherenkov photons per event With beam hole (R>13 cm): <600 Cherenkov photons per event

  7. Number of detected tracks per event (UrQMD) Beam hole = 13 cm

  8. Ring images in UrQMD event R(hole)=0 cm R(hole)=13 cm

  9. Cherenkov photon occupancy vs (x,y) in UrQMD events UrQMD PLUTO++

  10. Cherenkov photon density vs R (UrQMD) Average Cherenkov photon density per 1 cm2 is low, but eventually up to 10 photons can hit one cell. (Remember the photon detection efficiency is 20% which improve the detector load).

  11. Electron vertices in UrQMD events • Sources of electrons giving detected Cherenkov photons: • Target (primary electrons) • Front wall • Mirror • Air and radiator gas

  12. Pseudorapidity of electrons/positions giving detected Cherenkov photons Background Signal

  13. Detection efficiency vs p Background Signal

  14. Detection efficiency vs  Background Signal

  15. Pseudorapidity vs ring distance from the beam axis (Rhole=13cm) Background Signal

  16. Summary • RICH response to signal and background events is studied: • High efficiency of electron detection • High suppression of charged pions at high momenta • Beam hole influence to acceptance: • Reduces significantly RICH load • Suppresses background from pions • Reduces acceptance at high .

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