Nuclei as neutrino detectors

摘要

Neutrinos make reactions with nuclei by means of neutral current (NC) as well as charged current (CC). The solar neutrinos (solar-v) have relatively low energy of up to ≈15 MeV. In this low-energy limit, the main component of the NC is the axial-IV current caused by the spin-isospin (στ) operator, while that of the CC is both the axial-IV current, and also the IV current caused by the isospin (τ) operator. The nuclear στ and τ responses can be well studied by using high energy-resolution (~3He, t) reaction at the intermediate incident-energy of 140 MeV/nucleon. Since the reaction is caused by the strong interaction, we have a larger reaction rate. Therefore, NC and CC responses of nuclei to the solar-v can be studied efficiently. We first examine the properties of nuclear excitations that are induced by the CC for some of the nuclei that have been discussed as "good tools" for the study of solar-v. Also discussed are the properties of p-shell (mass number A = 5 - 16) and also sd-shell nuclei (A = 17 - 40) with the z-component of isospin T_z = (N - Z)/2 = ±1/2. We seek the possible use of these nuclei as good tools for the study of excitations by means of both NC and CC.