Recoilless Resonant Emission and Detection of Electron Antineutrinos

TL;DR

This paper explores the theoretical feasibility of recoilless resonant emission and detection of monoenergetic electron antineutrinos via Moessbauer effect in the 3H-3He system, discussing challenges and potential scientific insights.

Contribution

It analyzes the effects of line broadening and energy shifts on the possibility of observing Moessbauer antineutrinos, highlighting overlooked factors affecting resonance.

Findings

Homogeneous line broadening due to magnetic relaxation is significant.

Inhomogeneous broadening impacts resonance line width.

Energy shifts from lattice binding energies may hinder detection.

Abstract

Recoilless resonant capture of monoenergetic electron antineutrinos (Moessbauer antineutrinos) emitted in bound-state beta-decay in the system 3H - 3He is discussed. The recoilfree fraction including a possible phonon excitation due to local lattice expansion and contraction at the time of the nuclear transition, homogeneous and inhomogeneous line broadening, and the relativistic second-order Doppler effect are considered. It is demonstrated that homogeneous line broadening is essential due to stochastic magnetic relaxation processes in a metallic lattice. Inhomogeneous line broadening plays an equally important role. An essential issue which has been overlooked up to now, is an energy shift of the resonance line due to the direct influence of the binding energies of the 3H and 3He atoms in the lattice on the energy of the electron antineutrinos. This energy shift as well as the second-order Doppler shift exhibit variations in a non-perfect (inhomogeneous) lattice and may seriously jeopardize the observation of Moessbauer antineutrinos. If successful in spite of these enormous difficulties, Moessbauer antineutrino experiments could be used to gain new and deep insights into the nature of neutrino oscillations, determine the neutrino mass hierarchy as well as up to now unknown oscillation parameters, search for sterile neutrinos, and measure the gravitational redshift of electron antineutrinos in the field of the Earth.