2. 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 ---------------------------------------------------------------

3. SETUP USED IN CALCULATIONS

4. EVERYWHERE ARE PRESENTED DISTRIBUTIONS OF VALUES

6. MUON INPUT POINT TO WATER TANK

7. FIRST PMT HIT

9. PMT DISTRIBUTION

10. PMT HITS TIME HIGHT DISTRIBUTION r

15. COUNT RATE IN WATER TANK

16. RESULTS ----------------------------------------------------------------------------- By taking 1 and more fired PMT as muon trigger we 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

17. 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