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Ashra Report: VHE Neutrino Detection

Ashra Report: VHE Neutrino Detection. Koji Noda (ICRR, Univ. of Tokyo) for Ashra-1 collaboration DPF2006 Oct 31, 2006. Overview. Earth-skimming n t MC simulation Detector status Summary. 1. Earth-skimming n t. VHE neutrino candidates: AGN,GRB,GZK,,, Why Earth-skimming n t ?

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Ashra Report: VHE Neutrino Detection

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  1. Ashra Report:VHE Neutrino Detection Koji Noda (ICRR, Univ. of Tokyo) for Ashra-1 collaboration DPF2006 Oct 31, 2006

  2. Overview • Earth-skimming nt • MC simulation • Detector status • Summary Koji Noda, Univ. of Tokyo

  3. 1. Earth-skimming nt VHE neutrino candidates: AGN,GRB,GZK,,, Why Earth-skimming nt ? original idea: Fargion(1997), Domokos & Kovesi-Domokos(1998),,, Earth-skimming - larger & costless mass - first t detection Ice experiment -1km3 (1G ton) -mainly m detector complementary approach to PeV-EeV neutrino Koji Noda, Univ. of Tokyo

  4. Earth & Mauna Kea Earth & Mauna Kea as "target & filter" of nt - >100G ton target mass - thickness so that only t can exit the Earth Koji Noda, Univ. of Tokyo

  5. t generation from nt • n N interaction, factor uncertainty in s CTEQ4-DIS, <10% larger s than CTEQ6 • Energy dependent inelasticity [ref.] Gandhi et al., Astropart. Phys., 5, 81 (1996) • Earth density rock in the Big Island is denser than standard Koji Noda, Univ. of Tokyo

  6. dominant t t g X N Iyer Dutta et al., PRD, 63, 094020 (2001) t Energy Loss t loses its energy in the Earth through; 1. Ionization (a) 2. Bremsstrahlung (b) 3. Pair Production (b) 4. Photo-nuclear interaction (b) Koji Noda, Univ. of Tokyo

  7. 100 range [km] water 10 rock effect of energy loss 1012 1017 1020 1022 Tau Energy [eV] Range in the Earth t decay length tof E=1017-20eV is decelerated to E~1017eV in ~10km rock interaction length of conversion to n Fargion et al., ApJ, 613, 1285 (2004) Koji Noda, Univ. of Tokyo

  8. Decay of t Survivor t, however, decays in the atmosphere. observable air-shower t decay package TAUOLA (considering polarization of t ) - spectrum is NOT flat - many decay modes complicated air-shower Koji Noda, Univ. of Tokyo Esh /Et

  9. 2. MC Simulation only Cherenkov less BG, simple trigger shower geometry - self earth/mountain, first int. point tau decay - TAUOLA shower generation - CORSIKA shower shape fluctuation detection - self atmospheric absorption & detector MaunaKea Mauna Loa Koji Noda, Univ. of Tokyo

  10. Shower geometry Large light pool: ~1/10 @500m, ~1/1000 @1500m (dense air deflects particles) asymmetry by attenuation? <1%(500m), <5%(1500m) approx. to plain atmosphere 500m 20km Koji Noda, Univ. of Tokyo

  11. 1016eV leptonic (e-) core distance 260m 1016eV hadronic (p -) core distance 260m source Examples of Detection Koji Noda, Univ. of Tokyo

  12. 1013eV e- Discussions • proton BG ? nearly horizontal = atm. thickness >104g/cm2 only m can contribute (m ~1013eV is mainly by pair creation) ref) Cillis & Sciutto, PRD 64, 013010 (2001) need measurement & simulation • threshold energy ? • En ~0.75En : t (inelasticity) • ~0.39En : decay shower 1013eV secondary is detectable (light pool max.)~1014eV nt Koji Noda, Univ. of Tokyo

  13. radius distance Sensitivity ONLY Cherenkov, averaged geometry ref) Tseng et al., PRD 68, 063003 (2003) AGN: Neronov et al., PRL 89, 5, 051101-1 (2002) Preliminary TOTAL 0.20/yr Observation only with Cherenkov is meaningful By fluorescence, aperture will improve Koji Noda, Univ. of Tokyo

  14. 3. Detector Status Optics have been deployed - a few arc-minutes resolution - ready for BG measurement Cherenkov trigger is tested by sky observation - cosmic ray images are already obtained to be combined Koji Noda, Univ. of Tokyo

  15. Summary • Earth-skimming nt detection • MC simulation - complicated, but observable shower - Eth~1014eV, event rate ~0.2/yr • detector - to be completed soon • perspectives: - BG measurement on/near Mauna Kea - more detailed MC Koji Noda, Univ. of Tokyo

  16. Acknowledgements Ashra experiment is supported by - the Coordination Fund for Promoting Science and Technology, and Grant-in-Aid for Scientific Research, from the Ministry of Education, Science, Sports and Culture of Japan - the Joint Development Research at KEK - the collaborative development research program of NAOJ - the joint research program of ICRR and ISSP - the COE21 Program "Quantum Extreme Systems and Their Symmetries" from the University of Tokyo Two graduate students (including me) are supported by - "Research Fellowship for young scientists" from JSPS Koji Noda, Univ. of Tokyo

  17. Koji Noda, Univ. of Tokyo

  18.  A   A Domokos and Kovesi-Domokos, 1998 Fargion, 1997, 2002 Bertou et al., 2001 Feng et al., 2001 Bottai and Giurgola, 2002 Tseng et al., 2003 Koji Noda, Univ. of Tokyo

  19. Koji Noda, Univ. of Tokyo

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