Possibility of using ⁸¹Kr to detect solar neutrinos

Abstract

THE state of the experiment designed to detect solar neutrinos by the reaction ν+³⁷Cl→³⁷Ar (T_1/2 = 35d)+e⁻(threshold = 814 keV) has been summarised by Bahcall and Davis¹, who report essentially a null result for the average of many runs over the past few years. The experiment is sensitive only to a tiny fraction of the total flux, that is to neutrinos arising from the ⁸B decay (Table 1) and it is therefore essential to have another experiment which responds to the lower energy, more abundant neutrinos if the fundamental ideas about the mechanisms by which the Sun produces its energy are to be tested. There seem to be very few^1,2 experiments with this property and an interesting alternative approach has been suggested by Freedman et al.³. They hope to obtain a value of the average flux during the past few Myr by measuring the ²⁰⁵Pb produced in old, thallium-rich minerals in the reaction ν+²⁰⁵T1→²⁰⁵Pb (T_1/2 = 1.6×10⁷y)+e⁻ (threshold = 46 keV), which is sensitive to all parts of the neutrino-producing chain. The purpose of this communication is to investigate the feasibility of detecting solar neutrinos through the reaction ν+⁸¹Br→⁸¹Kr (T_1/2 = 2.1 × 10⁵ y)+e⁻ (threshold = 490 keV), which turns out to be sensitive mostly to the ⁷Be neutrinos, the second most abundant in the chain.