1. On the Prospect of Tau Neutrino Astronomy in GeV Energies and Beyond G.-L. Lin National Chiao-Tung U. Taiwan Moriond 2005

2. 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

3. The aspects of tau neutrino detections:  E > 10 6 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

4. 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  (  ) >  (  ).

5. The prospect of detecting galactic  : an illustration  The Flux CR Interstellar medium n p =1 particle /cm 3 Intrinsic Flux: Due to oscillation: Athar, Jezabek and Yasuda, 2000 Bento, Keränen and Maalampi, 2000

6. in the unit cm -2 s -1 sr -1 GeV -1 Primary comic ray proton spectrum T. K. Gaisser and M. Honda, 2002

7.  The flux of atmospheric background 2-flavor oscillation analysis Y. Ashie et al. [SK Collab.], 2004 We present the results with the best fit values H. Athar, hep-ph/0401242 H. Athar, F.-F. Lee &GLL, hep-ph/0407183 F.-F. Lee & GLL, hep-ph/0412383

8. Neutrino energy H. Athar, F.-F. Lee and GLL, hep-ph/0407183 Atmospheric  flux before Oscillations The , K production cross Section taken from T. K. Gaisser, astro-ph/0104327

9.  The intrinsic tau neutrino flux can be calculated by perturbative QCD supplemented by models for D s decays. L. Pasquali, M. H. Reno and I. Sarcevic, 1999

10. Neutrino energy Atmospheric tau neutrino flux after oscillations Downward to Horizontal Directions, Oscillations Occur in Atmosphere F.-F. Lee and GLL, hep-ph/0412383

11.   Galactic  =90 0  =66 0  =0 0 Neutrino energy F.-F. Lee and GLL, hep-ph/0412383 Comparison of galactic and atmospheric ’s– downward to horizontal directions

12. Neutrino energy Comparison in the upward direction Galactic-plane observable through  for E > TeV

13. 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.