Search for Resonant Absorption of Solar Axions Emitted in M1 Transition in $^{57}$Fe Nuclei

TL;DR

This paper reports a search for solar axions emitted during nuclear transitions in $^{57}$Fe, setting new upper limits on axion mass through detection of gamma rays from resonant absorption.

Contribution

It presents the first experimental search for resonant absorption of solar axions in $^{57}$Fe, establishing new upper bounds on axion mass.

Findings

New upper limit for axion mass: 151 eV at 90% confidence level.

Detection of gamma rays consistent with resonant absorption in $^{57}$Fe.

Improved constraints on hadronic axion properties.

Abstract

A search for resonant absorbtion of 14.4 keV solar axions by $^{57}$Fe target was performed. The Si(Li) detector placed inside the low-background setup was used to detect the $\gamma$-quanta appearing in the deexcitation of 14.4 keV nuclear level: $A+\rm{^{57}Fe} \to \rm{^{57}Fe^{*}} \to \rm{^{57}Fe} + \gamma$. The new upper limit for the hadronic axion mass have been obtained: $m_{A} \leq 151$ eV (90% C.L.) ($S$=0.5, $z$=0.56).