Electron Capture Beta Decay of Partially Polarized Nuclei

TL;DR

This paper calculates the spin excess of neutrinos emitted during electron capture beta decay in polarized nuclei, showing it exceeds previous estimates, with implications for directed neutrino sources.

Contribution

It provides a direct computation of neutrino spin excess in polarized nuclei, improving upon earlier simplified estimates.

Findings

Spin excess is greater than previously estimated.

Results are specific to $^{119}$Sb nuclei in ferromagnetic materials.

Potential application in directed neutrino radiation sources.

Abstract

We compute the spin excess for the neutrinos radiated in the process of electron capture beta decay of partially polarized nuclei. The results of computation are presented for the $^{119}$Sb nuclei polarized by the strong hyperfine field in a ferromagnetic substance. This system was suggested as a possible source of directed neutrino radiation. We directly compute the spin excess of radiated neutrinos and show that it is greater than that estimated previously under simplifying assumptions.