170 likes | 175 Vues
INIITIAL POINTS :. LNGS muon Angular Distribution / MACRO / - [1] Cylindrical symmetry PMT placement Muon Energy – 17.5 GeV Optical Photon Energy – 2–5 eV [ 620-280 nm] Photocathode Radius – 20 cm Photocathode Quantum Efficiency – 0.15 Water Transparency – 10 m Tyvek Reflactivity – [2]
E N D
INIITIAL POINTS: • LNGS muon Angular Distribution / MACRO / - [1] • Cylindrical symmetry PMT placement • Muon Energy – 17.5 GeV • Optical Photon Energy – 2–5 eV [ 620-280 nm] • Photocathode Radius – 20 cm • Photocathode Quantum Efficiency – 0.15 • Water Transparency – 10 m • Tyvek Reflactivity – [2] • PMT Number - 45 – 150 [ 0.3 – 1.0 % ] • Cherenkov photons – 300 photon/cm • MaGe frame • ---------------------------------------------------------------
RESULTS -----------------------------------------------------------------------------By taking 1 and more fired PMT as muon triggerwe will have • 45 PMT give reduction factor of background ~ 170 / 99.41% / • 110 PMT give reduction factor of background ~ 430/ 99.77% / • Input count rate is ~ 3500 Hz for N_pmt >0 • Such reduction input External Gammas Background • at level 10^-3 cpy/kg/keV
REFERENCES • [1] S.Ahlen et al.,”Muon Astronomy With the Macro detector” , App.J. 412(1993) • [2] hep-ex/0404039 “ A new Ge-76 Double Beta decay Experiment at LNGS” • [3] C.Arpesella, Nucl.Phys.( Proc. Suppl. ) A 28 (1992) 420-424