20,731 research outputs found
Neutrino–nucleus reactions and nuclear structure
The methods used in the evaluation of the neutrino–nucleus cross section are reviewed. Results are shown for a variety of targets of practical importance. Many of the described reactions are accessible in future experiments with neutrino sources from the pion and muon decays at rest, which might be available at the neutron spallation facilities. Detailed comparison between the experimental and theoretical results would establish benchmarks needed for verification and/or parameter adjustment of the nuclear models. Having a reliable tool for such calculation is of great importance in a variety of applications, e.g. the neutrino oscillation studies, detection of supernova neutrinos, description of the neutrino transport in supernovae and description of the r-process nucleosynthesis
Reactor antineutrino spectra and their application to antineutrino-induced reactions. II
The antineutrino and electron spectra associated with various nuclear fuels are calculated. While there are substantial differences between the spectra of different uranium and plutonium isotopes, the dependence on the energy and flux of the fission-inducing neutrons is very weak. The resulting spectra can be used for the calculation of the antineutrino and electron spectra of an arbitrary nuclear reactor at various stages of its refueling cycle. The sources of uncertainties in the spectrum are identified and analyzed in detail. The exposure time dependence of the spectrum is also discussed. The averaged cross sections of the inverse neutron β decay, weak charged and neutral-current-induced deuteron disintegration, and the antineutrino-electron scattering are then evaluated using the resulting ν̅_e spectra.
[RADIOACTIVITY, FISSION 235U, 238U, (^239)Pu, (^240)Pu, (^241)Pu, antineutrino and electron spectra calculated. σ for ν̅ induced reactions analyzed.
Uncertainties in nuclear transition matrix elements for neutrinoless decay II: the heavy Majorana neutrino mass mechanism
Employing four different parametrization of the pairing plus multipolar type
of effective two-body interaction and three different parametrizations of
Jastrow-type of short range correlations, the uncertainties in the nuclear
transition matrix elements due to the exchange of heavy
Majorana neutrino for the transition of neutrinoless
double beta decay of Zr, Zr, Mo, Mo, Ru,
Pd, Te and Nd isotopes in the PHFB model are
estimated to be around 25%. Excluding the nuclear transition matrix elements
calculated with Miller-Spenser parametrization of Jastrow short range
correlations, the uncertainties are found to be 10%-15% smaller
Crystal Nucleation in a Supercooled Liquid with Glassy Dynamics
In simulations of supercooled, high-density liquid silica we study a range of
temperature T in which we find both crystal nucleation, as well as the
characteristic dynamics of a glass forming liquid, including a breakdown of the
Stokes-Einstein relation. We find that the liquid cannot be observed below a
homogeneous nucleation limit (HNL) at which the liquid crystallizes faster than
it can equilibrate. We show that the HNL would occur at lower T, and perhaps
not at all, if the Stokes-Einstein relation were obeyed, and hence that glassy
dynamics plays a central role in setting a crystallization limit on the liquid
state in this case. We also explore the relation of the HNL to the Kauzmann
temperature, and test for spinodal-like effects near the HNL.Comment: 4 pages, 4 figure
A simple model of reactor cores for reactor neutrino flux calculations for the KamLAND experiment
KamLAND is a reactor neutrino oscillation experiment with a very long
baseline. This experiment successfully measured oscillation phenomena of
reactor antineutrinos coming mainly from 53 reactors in Japan. In order to
extract the results, it is necessary to accurately calculate time-dependent
antineutrino spectra from all the reactors. A simple model of reactor cores and
code implementing it were developed for this purpose. This paper describes the
model of the reactor cores used in the KamLAND reactor analysis.Comment: 14 pages, 7 figures, submitted to Nuclear Instruments and Methods in
Physics Research
Single-photon excitation of a coherent state: catching the elementary step of stimulated light emission
When a single quantum of electromagnetic field excitation is added to the
same spatio-temporal mode of a coherent state, a new field state is generated
that exhibits intermediate properties between those of the two parents. Such a
single-photon-added coherent state is obtained by the action of the photon
creation operator on a coherent state and can thus be regarded as the result of
the most elementary excitation process of a classical light field. Here we
present and describe in depth the experimental realization of such states and
their complete analysis by means of a novel ultrafast, time-domain, quantum
homodyne tomography technique clearly revealing their non-classical character.Comment: 9 pages, 9 figures. Accepted for publication in Phys. Rev.
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