Electron Neutrino Flux Research Articles

Direct approach to resolve the solar-neutrino problem.

A direct approach to resolve the solar-neutrino problem would be to observe neutrinos by use of both neutral-current and charged-current reactions. Then, the total neutrino flux and the electron neutrino flux would be separately determined to provide independent tests of the neutrino-oscillation hypothesis and the standard solar model. A large heavy-water Cherenkov detector, sensitive to neutrinos from /sup 8/B decay via the neutral-current reaction ..nu..+d..--> nu..+p+n and the charged-current reaction ..nu../sub e/+d..-->..e/sup -/+p+p is suggested for this purpose.

Design of an enhanced 1 GeV electron neutrino beam

An enhanced ν e beam would be useful for experiments that have been proposed to investigate the time evolution of a ν e beam or to test the universality of ν e and ν μ interactions. We have performed detailed calculations to maximize the flux of electron neutrinos through a detector while minimizing the more copious muon neutrinos produced at 30 GeV proton accelerators. The ν e beam is formed from the semi-leptonic decay modes of the neutral kaon. Muon neutrinos generated by decays of charged pions and kaons are suppressed by a dipole sweeping magnet. The ν e/ ν μ ratio is enhanced from its usual value of ∼ 1 1000 to a value of ∼ 1 2 , albeit at a low flux. We find with this design a typical flux of 1.5 × 10 7 ν e/m 2 s. We find that a high magnetic field (≥ 40 kG) is essential to achieve this ν e/ ν μ enhancement. Although the use of collimators and/or plugs inside the magnet reduces the ν μ flux, the ν e flux is also diminished so that there is little beneficial effect on the ν e/ ν μ ratio. Magnetic focusing horns and quadrupole beams do not enhance the ν e/ ν μ ratio. The accuracy of the energy dependence of the calculation, as well as the absolute normalization of the fluxes, is determined by a subsidiary calculation of the ν μ yield from the magnetic horn focused beam at Brookhaven National Laboratory. This calculation is the first to our knowledge to agree well with the ν μ yield as measured in the BNL seven foot bubble chamber.

The Solar Neutrino Problem—A Progress(?) Report

The conflict between observation and theoretical prediction of the flux of electron neutrinos from the sun has advanced in the past year from being merely difficult to understand to being impossible to live with. We review here attempts to explore the nature of the conflict, to seek possible ways out of it, and to inquire into additional experiments that have the capability either of resolving the conflict or at least of deciding which branch of physics or astrophysics is responsible for it.

Experimental Test of Baryon Conservation and Neutrino Flux Limits

An experiment has been performed in which events not directly attributable to cosmic rays or natural radioactivity were observed for 4500 h in a 200-liter liquid scintillation detector. Shielding from cosmic rays was obtained through anticoincidence techniques and by locating the detector 585 m underground. Background from natural radioactivity was reduced by placing high-energy requirements on acceptable events. The residual signal has been used to establish new lower limits on the stability of nucleons and a new upper limit on the product of the cross section and the electron neutrino (${\ensuremath{\nu}}_{e}, {\overline{\ensuremath{\nu}}}_{e}$) flux whatever its origin, providing its energy is 400 MeV and >30 MeV (${\ensuremath{\nu}}_{e}$) or > 12 MeV (${\overline{\ensuremath{\nu}}}_{e}$). Depending on the assumed decay modes, nucleon lifetime limits in the range 0.6\ifmmode\times\else\texttimes\fi{}${10}^{28}$ to 4\ifmmode\times\else\texttimes\fi{}${10}^{28}$ years were obtained. The upper limits on the neutrino cross-section flux products are $8.5\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}38}{\ensuremath{\nu}}_{e}$ ${\mathrm{sec}}^{\ensuremath{-}1}$ and $3.2\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}38}{\overline{\ensuremath{\nu}}}_{e}$ ${\mathrm{sec}}^{\ensuremath{-}1}$.