Muon simulation status from Dubna Valery Rodionov ITEP, April 28, 2010. Outlook: Muon system in PandaRoot MC: DY (-,+) registration efficiency by muon system as function of polar angle of DY effective photon: -- muon detectors only: with/without magnetic field -- full PANDA setup(material): with/without magnetic field -- how to improve acceptance MC: J/ (-,+) registration efficiency by muon system as function of polar angle of J/ XXXI Panda meeting, December 7-12, 2009

PANDA setup in PandaRoot Muon system in PANDA TS/barrel: 12 layers of MDT inside the yoke + “zero” bi-layer. TS/endcap: 5 layers MuonFilter: 4 x (60mm/Fe + MDT) FS: “zero” bi-layer+16 x(60mm/Fe +MDT)

DY (- , +) registration efficiency by muon system: selection criterion for (- , +) rejection: No hit (muon system) at least for one muon from pair. The point of study: the “cross”-like hole in Target Spectrometer. The fraction of muons from the DY pairs (one or both) are passing through the hole (Endcap+MuonFilter) without giving the hits in MDT’s.  The efficiency registration by Forward muon system. If we loose (no hits in muon system) at least one muon from the (- , +)  an event is rejected. The task: MC based registration efficiency estimation for such type events. MC: full setup calculation. The only muon system is shown. For demonstation: 80 (- , +) in one event; only - are visible

Geometrical acceptance of muon system in case of: muon detectors only (without Solenoid and Yoke). Pythia as event generator (40K DY events) + PandaRoot. Option: with/without magnetic field in Solenoid/Dipole. PANDA muon system. For demonstration the geometrical acceptance of muon system, the simulated 50 DY events are presented on the same figure.

Geometrical acceptance study of muon system in case of: full PANDA setup (material). Pythia as event generator (40K DY events) + PandaRoot. Option: with/without magnetic field in Solenoid/Dipole. Polar angle distribution of DY photons.

Current design: Endcap: 3 Layers with small hole + 2 Layers with holes for DC MF: 4 Layers with holes for DC An option: Endcap: 4 Layers with small hole + 1 Layers with holes for DC MF: 4 Layers with holes for DC Front and cut view of Endcap/MF. Left: current design. Right: Optional.

Geometrical acceptance study of muon system in case of: full PANDA setup (material). Pythia as event generator (40K DY events) + PandaRoot. Option: with/without magnetic field in Solenoid/Dipole. Option#1: 4 Layers with small hole + 1 Layers with holes for DC

Stopping in Dipole/Ecal(Forward) Geometrical acceptance study of muon system in case of: full PANDA setup (material). Pythia as event generator (40K DY events) + PandaRoot. Option#1: with magnetic field in Solenoid/Dipole. Finally: ~12% losses of DY events with selection criterion: no hits in muon system for at least one muon from DY (-,+). The relative loses for DY events in muon system 65% Forward region 5% “beam pipe” 30% Stopping in Dipole/Ecal(Forward) XXXI Panda meeting, December 7-12, 2009

Geometrical acceptance study of muon system in case of: full PANDA setup (material). Pythia as event generator (37K J/(-,+ events) + PandaRoot. Option: with/without magnetic field in Solenoid/Dipole. Polar angle distribution of J/.

Conclusion: The MC (PandaRoot) study of DY(-,+) and J/ (-,+) registration efficiency by muon system was started In current muon system design: a) the acceptance for DY pairs may be increased to ~ 88% by introducing minor changes in MDT layers design in Endcap  this is a point for further studies/discussions b) the acceptance for J/ looks better and less sensitive to magnetic field as compared to DY 3) In order to get more detailed results, we need the higher statistical samples (at least 1M events for each process  DY, J/ and D-mesons)