An experiment for the measurement of the bound-beta decay of the free neutron

TL;DR

This paper reports an experiment measuring the hyperfine-state population of hydrogen from neutron bound-beta decay, aiming to test neutrino helicity and weak interaction couplings with improved precision.

Contribution

It introduces a novel experimental setup using a high-flux reactor beam tube to measure hydrogen hyperfine states, enhancing constraints on weak force parameters.

Findings

Background free hydrogen detection rate of ca. 3 s$^{-1}$

Potential to improve constraints on neutrino helicity by a factor of ten

Enhanced sensitivity to scalar and tensor contributions in weak interactions

Abstract

The hyperfine-state population of hydrogen after the bound-beta decay of the neutron directly yields the neutrino left-handedness or a possible right-handed admixture and possible small scalar and tensor contributions to the weak force. Using the through-going beam tube of a high-flux reactor, a background free hydrogen rate of ca. 3 s$^{-1}$ can be obtained. The detection of the neutral hydrogen atoms and the analysis of the hyperfine states is accomplished by Lamb shift source type quenching and subsequent ionization. The constraints on the neutrino helicity and the scalar and tensor coupling constants of weak interaction can be improved by a factor of ten.