Reactor Neutrino Spectrum Research Articles

Precision spectroscopy with reactor antineutrinos

In this work we present an accurate parameterization of the anti-neutrino flux produced by the isotopes 235U, 239Pu and 241Pu in nuclear reactors. We determine the coefficients of this parameterization, as well as their covariance matrix, by performing a fit to spectra inferred from experimentally measured beta spectra. Subsequently we show that flux shape uncertainties play only a minor role in the KamLAND experiment, however, we find that future reactor neutrino experiments to measure the mixing angle $\theta_{13}$ are sensitive to the fine details of the reactor neutrino spectra. Finally, we investigate the possibility to determine the isotopic composition in nuclear reactors through an anti-neutrino measurement. We find that with a 3 month exposure of a one ton detector the isotope fractions and the thermal reactor power can be determined at a few percent accuracy, which may open the possibility of an application for safeguard or non-proliferation objectives.

Brief Calculation of Neutrino Energy Spectra by the Use of Nuclear Data Files

Nuclear reactors generate a highly intense flux of electron-antineutrinos from fission products through β− decay, and a slight amount of electron-neutrinos through either β+ decay or electron capture. Neutrino energy spectra are usually calculated by the β decay theory. Since the reactor neutrinos are emitted from a great number of nuclides, the calculation requires a lot of level scheme of these nuclides. Nuclear data files, however, are available these days. It is possible to evaluate the electron-antineutrino and -neutrino spectra for a nuclear reactor on the basis of nuclear data files (JENDL-FP-Decay-Data-File-2000, JENDL-3.3)1, 2).In the study, we consider β transition of 420 nuclides for electron-antineutrino spectra and 120 nuclides for electron-neutrinos. We derive electron-neutrino and -antineutrino spectra in the energy range of 10 keV to 8 MeV from nuclear data files. The method gives good agreement with other studies for electron-antineutrino spectra. We show a simple method to estimate the reactor neutrino spectra without complicated computation.

Sensitivities of low energy reactor neutrino experiments

The low energy part of the reactor neutrino spectra has not been measured experimentally. Its uncertainties limit the sensitivities in certain reactor neutrino experiments. This paper discusses the origin of these uncertainties and examines their effects on the measurements of neutrino interactions with electrons and nuclei. The discrepancies between previous results and the standard model expectations can be explained by the underestimation of the reactor neutrino spectra at low energies. To optimize the experimental sensitivities, measurements for ν̄e–e cross-sections should focus on events with large (>1.5 MeV) recoil energy while those for neutrino magnetic moment searches should focus on events <100 keV. The merits and attainable accuracies for neutrino–electron scattering experiments using artificial neutrino sources are discussed.