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Moriond 2005 On the Prospect of Tau Neutrino Astronomy in GeV Energies and Beyond G.-L. Lin National Chiao-Tung U. Taiwan Outline • The current aspects of tau neutrino detections • The reward for an effective discrimination of from other neutrino flavors— illustrated with the detection of galactic , atmospheric background considered in detail. • Conclusion The aspects of tau neutrino detections: E > 106 GeV Double bang events 2 showers separated by roughly 50(E/PeV) m J. G. Learned and S. Pakvasa 1995 H. Athar, G. Parente and E. Zas 2000 E between GeV and PeV: make use of shower properties Different shower distributions for NC and CC+ decays T. Stanev 1999 Upward atmospheric ’s ~100 GeV-- T. Stanev, 1999 Extragalactic ’s -- S. I. Dutta, M. H. Reno and I. Sarcevic, 2000 R=shower event rate/ muon event rate ()~() in the above. It will be rewarding if one can do better in discriminating from other flavors—in the situation () > (). The prospect of detecting galactic : an illustration The Flux CR Interstellar medium np=1 particle /cm3 p p , K , Ds X , Intrinsic Flux: 2 e Due to oscillation: e on Earth Athar, Jezabek and Yasuda, 2000 Bento, Keränen and Maalampi, 2000 Primary comic ray proton spectrum p E p dN p / dE p , T. K. Gaisser and M. Honda, 2002 p E p 1.49 E p 2.15 exp 0.21 E p 2.74 in the unit cm-2s-1sr-1GeV-1 The flux of atmospheric background 2-flavor oscillation analysis Y. Ashie et al. [SK Collab.], 2004 sin 2 2 23 0.9, 1.9 103 eV 2 m31 3 103 eV 2 2 We present the results with the best fit values sin 2 2 23 1, m31 2.4 103 eV 2 2 H. Athar, hep-ph/0401242 H. Athar, F.-F. Lee &GLL, hep-ph/0407183 F.-F. Lee & GLL, hep-ph/0412383 Atmospheric flux before Oscillations p A M X , M , K , charm hadrons Fraction M X / total . H. Athar, F.-F. Lee and GLL, hep-ph/0407183 and comparable beyond this energy from Ds decays The , K production cross Section taken from T. K. Gaisser, astro-ph/0104327 Neutrino energy The intrinsic tau neutrino flux can be calculated by perturbative QCD supplemented by models for Ds decays. p A Ds X Ds ; X L. Pasquali, M. H. Reno and I. Sarcevic, 1999 Atmospheric tau neutrino flux after oscillations : zenith angle cos 1, 0.8, 0.6, 0.4, 0.2, 0 From bottom to top Downward to Horizontal Directions, Oscillations Occur in Atmosphere F.-F. Lee and GLL, hep-ph/0412383 Neutrino energy dN0 dN0 P dN 1 P d log10 E d log10 E d log10 E Comparison of galactic and atmospheric ’s– downward to horizontal directions =660 =900 =00 Galactic Neutrino energy F.-F. Lee and GLL, hep-ph/0412383 Comparison in the upward direction Galactic-plane observable through for E> TeV Neutrino energy Conclusion • We have outlined the current strategy of identifying astrophysical . • We made a detailed comparison between galactic and atmospheric neutrino flux. • We showed that an effective discrimination of from other neutrino flavors is rewarding. The galactic-plane can be seen through in GeV to TeV energies.
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