0000000000055745
AUTHOR
H. Nunokawa
showing 6 related works from this author
Pulsar Velocities without Neutrino Mass
1998
We show that pulsar velocities may arise from anisotropic neutrino emission induced by resonant conversions of massless neutrinos in the presence of a strong magnetic field. The main ingredient is a small violation of weak universality and neither neutrino masses nor magnetic moments are required.
Active-active and active-sterile neutrino oscillation solutions to the atmospheric neutrino anomaly
1998
We perform a fit to the full data set corresponding to 33.3 kt-yr of data of the Super-Kamiokande experiment as well as to all other experiments in order to compare the two most likely solutions to the atmospheric neutrino anomaly in terms of oscillations in the $\nu_\mu \to \nu_\tau$ and $\nu_\mu \to \nu_s$ channels. Using state-of-the-art atmospheric neutrino fluxes we have determined the allowed regions of oscillation parameters for both channels. We find that the $\Delta m^2$ values for the active-sterile oscillations (both for positive and negative $\Delta m^2$) are higher than for the $\nu_\mu \to \nu_\tau$ case, and that the increased Super-Kamiokande sample slightly favours $\nu_\mu…
Atmospheric neutrino observations and flavor changing interactions
1999
Flavor changing (FC) neutrino-matter interactions can account for the zenith-angle dependent deficit of atmospheric neutrinos observed in the SuperKamiokande experiment, without directly invoking neither neutrino mass, nor mixing. We find that FC $\nu_\mu$-matter interactions provide a good fit to the observed zenith angle distributions, comparable in quality to the neutrino oscillation hypothesis. The required FC interactions arise naturally in many attractive extensions of the Standard Model.
Type-II Supernovae and Neutrino Magnetic Moment
1998
The present solar and atmospheric neutrino data together with the LSND results and the presence of hot dark matter (HDM) suggest the existence of a sterile neutrino at the eV scale. We have reanalysed the effect of resonant {\sl sterile} neutrino conversions induced by neutrino magnetic moments in a type-II supernova. We analyse the implications of $\nu_e-\nu_s$ and $\bar{\nu}_e-\bar{\nu}_s$ ($\nu_s$ denotes sterile neutrino) conversions for the supernova shock re-heating, the detected $\bar\nu_e$ signal from SN1987A and the $r$-process nucleosynthesis hypothesis. Using reasonable magnetic field profiles we determine the sensitivity of these three arguments to the relevant neutrino paramete…
Feasibility and physics potential of detecting $^8$B solar neutrinos at JUNO
2021
The Jiangmen Underground Neutrino Observatory (JUNO) features a 20 kt multi-purpose underground liquid scintillator sphere as its main detector. Some of JUNO's features make it an excellent location for 8B solar neutrino measurements, such as its low-energy threshold, high energy resolution compared with water Cherenkov detectors, and much larger target mass compared with previous liquid scintillator detectors. In this paper, we present a comprehensive assessment of JUNO's potential for detecting 8B solar neutrinos via the neutrino-electron elastic scattering process. A reduced 2 MeV threshold for the recoil electron energy is found to be achievable, assuming that the intrinsic radioactive …
Optimization of the JUNO liquid scintillator composition using a Daya Bay antineutrino detector
2021
To maximize the light yield of the liquid scintillator (LS) for the Jiangmen Underground Neutrino Observatory (JUNO), a 20 t LS sample was produced in a pilot plant at Daya Bay. The optical properties of the new LS in various compositions were studied by replacing the gadolinium-loaded LS in one antineutrino detector. The concentrations of the fluor, PPO, and the wavelength shifter, bis-MSB, were increased in 12 steps from 0.5 g/L and <0.01 mg/L to 4 g/L and 13 mg/L, respectively. The numbers of total detected photoelectrons suggest that, with the optically purified solvent, the bis-MSB concentration does not need to be more than 4 mg/L. To bridge the one order of magnitude in the detect…