Search for Solar Axions Produced in the $p + d \rightarrow\rm{^3He}+ A$ Reaction

TL;DR

This paper searches for solar axions produced in a specific nuclear reaction, setting new limits on axion couplings and fluxes using BGO detectors and analyzing positron flux data.

Contribution

It provides the first model-independent limits on axion-photon and axion-nucleon couplings from solar axion detection and constrains axion-electron couplings across a range of masses.

Findings

Set a limit on $|g_{Ae} imes g_{AN}|$ of $3.2 imes 10^{-9}$ for massless axions.

Derived upper bounds on $g_{Ae}$ for axions with masses 0.1-1.0 MeV.

Established new constraints on axion-electron coupling from interplanetary positron flux data.

Abstract

A search for the axioelectric absorption of 5.5-MeV solar axions produced in the $p+d\rightarrow \rm{^3He}+\gamma(5.5 \rm{MeV})$ reaction was performed with two BGO detectors placed inside a low-background setup. A model independent limit on axion-photon and axion-nucleon couplings was obtained: $|g_{Ae}\times g_{AN}| \leq 3.2\times 10^{-9} (m_A=0)$. Constraints on the axion-electron coupling constant were obtained for axions with masses in the $(0.1-1.0)$ MeV range: $g_{Ae}\leq (1.8-9.0)\times 10^{-7}$. The solar positron flux from $A\rightarrow e^-+e^+$ decay was determined for axions with masses $m_A > 2m_e$. Using the existing experimental data on the interplanetary positron flux, a new constraint on the axion-electron coupling constant for axions with masses in the $(1.2-5.4)$ MeV range was obtained: $g_{Ae} \leq (1-5)\times 10^{-17}$.