Browsing by Author "Liu, Tsung-Che"

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Probing neutrino flavor transition mechanism with ultrahigh energy astrophysical neutrinos
(2014-02-06)
Lai, Kwang-Chang
;
Lin, Guey-Lin
;
Liu, Tsung-Che
;
物理研究所
;
Institute of Physics
Observation of ultrahigh energy astrophysical neutrinos and identification of their flavors have been proposed for future neutrino telescopes. The flavor ratio of astrophysical neutrinos observed on the Earth depends on both the initial flavor ratio at the source and flavor transitions taking place during propagations of these neutrinos. The flavor transition mechanisms are well classified with our model-independent parametrization. We find that a new parameter R equivalent to phi(e)/(phi(mu) + phi(tau)) can probe directly the flavor transition in the framework of our model-independent parametrization, without the assumption of the nu(mu)-nu(tau) symmetry. A few flavor-transition models are employed to test our parametrization with this new observable. The observational constraints on flavor transition mechanisms by the new observable are discussed through our model- independent parametrization.
Probing neutrino mass hierarchy by comparing the charged-current and neutral-current interaction rates of supernova neutrinos
(2016-07)
Lai, Kwang-Chang
;
Lee, Fei-Fan
;
Lee, Feng-Shiuh
;
Lin, Guey-Lin
;
Liu, Tsung-Che
The neutrino mass hierarchy is one of the neutrino fundamental properties yet to be determined. We introduce a method to determine neutrino mass hierarchy by comparing the interaction rate of neutral current (NC) interactions, nu((nu) over bar)+p -> v((v) over bar) +p, and inverse beta decays (IBD), (nu) over bar (e)+p -> n + e(+), of supernova neutrinos in scintillation detectors. Neutrino flavor conversions inside the supernova are sensitive to neutrino mass hierarchy. Due to Mikheyev-Smirnov-Wolfenstein effects, the full swapping of (nu) over bar (e) flux with the (nu) over bar (x)(x = mu, tau) one occurs in the inverted hierarchy, while such a swapping does not occur in the normal hierarchy. As a result, more high energy IBD events occur in the detector for the inverted hierarchy than the high energy IBD events in the normal hierarchy. By comparing IBD interaction rate with the mass hierarchy independent NC interaction rate, one can determine the neutrino mass hierarchy.
Simulating neutron propagations with FLUKA, GEANT4 and MCNP
(2007)
Yeh, Yung-Shun
;
Wang, Chung-Hsiang
;
Liu, Hong-Ming
;
Liu, Tsung-Che
;
Lin, Guey-Lin
We perform simulations on neutron transport properties for neutrons with energies less than 500 MeV. The simulation packages FLUKA, GEANT4 and MCNP are used. The neutron energy distributions and attenuation lengths, which are resulted from a mono-energetic initial neutron beam traversing a given thickness of medium, are presented.