Browsing by Author "Athar, H"

Now showing 1 - 7 of 7

Comparison of high-energy galactic and atmospheric tau neutrino flux
(2003-01-01)
Athar, H
;
Cheung, KM
;
Lin, GL
;
Tseng, JJ
;
物理研究所
We compare the tau neutrino flux arising from the galaxy and the earth atmosphere for 10(3) <= E/GeV <= 10(11). The intrinsic and oscillated tau neutrino fluxes from both sources are calculated. The intrinsic galactic v(tau) flux (E >= 10(3) GeV) is calculated by considering the interactions of high-energy cosmic-rays with the matter present in our galaxy, whereas the oscillated galactic v, flux is coming from the oscillation of the galactic v(mu), flux. For the intrinsic atmospheric v, flux, we extend the validity of a previous calculation from E <= 10(6) GeV up to E <= 10(11) GeV. The oscillated atmospheric v, flux is, on the other hand, rather suppressed. We find that, for 10(3) <= E/GeV <= 5.10(7), the oscillated v(tau) flux along the galactic plane dominates over the maximal intrinsic atmospheric v(tau) flux, i.e., the flux along the horizontal direction.
Comparison of high-energy galactic and atmospheric tau neutrino flux
(2003-03-01)
Athar, H
;
Cheung, K
;
Lin, GL
;
Tseng, JJ
;
物理研究所
We compare the tau neutrino flux arising from the galaxy and the earth atmosphere for 10(3) less than or equal to E/GeV less than or equal to 10(11). The intrinsic and oscillated tau neutrino fluxes from both sources are calculated. The intrinsic galactic nu(tau) flux (E greater than or equal to 10(3) GeV) is calculated by considering the interactions of high-energy cosmic-rays with the matter present in our galaxy, whereas the oscillated galactic nu(tau) flux is coming from the oscillation of the galactic nu(mu) flux. For the intrinsic atmospheric nu(tau) flux, we extend the validity of a previous calculation from E less than or equal to 10(6) GeV up to E less than or equal to 10(11) GeV. The oscillated atmospheric nu(tau) flux is, on the other hand, rather suppressed. We find that, for 10(3) less than or equal to E/GeV less than or equal to 5 x 10(7), the oscillated nu(tau) flux along the galactic plane dominates over the maximal intrinsic atmospheric nu(tau) flux, i.e., the flux along the horizontal direction. We also briefly mention the presently envisaged prospects for observing these high-energy tau neutrinos. (C) 2002 Elsevier Science B.V. All rights reserved.
Energy spectrum of tau leptons induced by the high energy Earth-skimming neutrinos
(2003-09-15)
Tseng, JJ
;
Yeh, TW
;
Athar, H
;
Huang, MA
;
Lee, FF
We present a semianalytic calculation of the tau-lepton flux emerging from the Earth induced by incident high energy neutrinos interacting inside the Earth for 10(5)less than or equal toE(nu)/GeVless than or equal to10(10). We obtain results for the energy dependence of the tau-lepton flux coming from the Earth-skimming neutrinos, because of the neutrino-nucleon charged-current scattering as well as the resonant (nu) over bar (e)e(-) scattering. We illustrate our results for several anticipated high energy astrophysical neutrino sources such as the active galactic nuclei, the gamma-ray bursts, and the Greisen-Zatsepin-Kuzmin neutrino fluxes. The tau-lepton fluxes resulting from rock-skimming and ocean-skimming neutrinos are compared. Such comparisons can render useful information about the spectral indices of incident neutrino fluxes.
Muon pair production by electron-photon scatterings
(2001-10-01)
Athar, H
;
Lin, GL
;
Tseng, JL
;
物理研究所
;
Institute of Physics
The cross section for muon pair productions by electrons scattering over photons, sigma (MPP), is calculated analytically in the leading order. It is pointed out that for the center-of-mass energy range s greater than or equal to 5m(mu)(2), the cross section sigma (MPP) is less than 1 mub. The differential energy spectrum for either of the resulting muons is given for the purpose of high-energy neutrino astronomy. An implication of our result for a recent suggestion concerning the high-energy cosmic neutrino generation through this muon pair is discussed.
Neutrino spin-flip effects in active galactic nuclei
(2002-06-01)
Mughal, MA
;
Athar, H
;
物理研究所
;
Institute of Physics
We study the effects of neutrino spin-flips in the magnetic field, BAGN, of an active galactic nuclei (AGN) for high-energy neutrinos (E greater than or equal to 10(6) GeV) originating from the AGN, induced by an interplay of a violation of the equivalence principle parameterized by Deltaf and the twist in B-AGN. We point out that a conversion effect may exist for Deltaf similar to 10(-34)(deltam(2)/10(-5) eV(2)) independent of the gravity mixing angle. Observational consequences for this conversion effect are discussed.
On possibility of the tau neutrino astronomy in GeV energies
(2005-06-01)
Athar, H
;
Lee, FF
;
Lin, GL
;
物理研究所
;
Institute of Physics
We discuss the possibility of searching the galactic-plane tau neutrinos in GeV energies.
Pev cosmic neutrinos from the mountains
(2004-05-30)
Yeh, P
;
Athar, H
;
La Barbera, N
;
Bouaissi, S
;
Catalano, O
The NuTel collaboration is building a wide field-of-view Cerenkov telescope to be installed on a mountain site for observing near horizontal air showers emerging from another mountain. Cosmic tau neutrinos is the primary source of such showers. This technique will be realized for the first time in the v, energy range of 2 PeV to 1000 PeV. The telescope has enough sensitivity to observe cosmic neutrinos from sources like Active Galactic Nuclei and Galactic Center assuming fluxes from current theoretical models.