1. Test of Monte-Carlo models with the L3+C muon spectrum measurement Presented by Yuqian Ma For XIII ISCRVHE at Pylos, 6-11 Sep 2004, Greece IHEP, Beijing China Qingqi Zhu, Yuqian Ma, Linkai Ding, Chao Zhang

2. Precise measurement of muon spectrum in 20- 3000GeV is achieved by L3+C experiment. What we can do with this spectrum? -- Test of the MC code; -- Derive the atmospheric neutrino spectrum. In this work, we start from vertical muon spectrum of L3+C

3. About primary CR spectrum The spectrum index of proton is referenced from the data book by “particle Data Group”, in which the index 2.50 for <100 GeV, 2.66 for 100-1000 GeV for VHE primary protons, the index changed with energy really. The select of 2.6 is a little flat than 2.68 of BESS, but within the error of BESS, the integral intensity is from BESS(38), The index of Helium is from RUNJOB.

4. MC simulation Software: COMUGEN based on Minijet model Parameters selection of Primary spectrum Power law energy band For protons: -2.60 22 -1000 GeV I p (>22GeV) = 38 / (m 2 s sr) (from BESS) -2.78 >1000 GeV For Hellium -2.68 > 88 GeV I p (>88GeV) = 2.09 / (m 2 s sr) (from RUNJOB) For CNO -2.60 > 500 GeV I p (>500GeV)=0.09 / (m 2 s sr) 10% of uncertainty is taken into account.

5. COMUGEN is based on minijet model

6. Red line comes from 10% error of primary spectrum Muon spectrum measured by L3+C and MC

7. MC results comparing L3+C and others measurement Red line: this work, 10% error of primary spectrum taken account MC result from Cosika had been presented by Pierre Le Coultre for L3+C, on NOON, 2002

8. MC result of atmospheric neutrino flux

9. The ratio of survival muons is compatible with ν μ / ν e ratio

10. Summary MC studying has been made for atmospheric muon spectrum by COMUGEN, which shows compatible with L3+C vertical muon flux measurement. Further MC will be done to investigate the flux in various zenith angle. L3+C precision spectrum can be used for test of MC generator. The vertical energy neutrino spectrum in high energy band have been obtained.

11. Thank you