Search for Solar Axions Produced in the $p+d\to {}^3\mathrm{H}\mathrm{e}+A$ Reaction

A search for the axioelectric absorption of 5.5-MeV solar axions produced in the $p+d\to {}^3\mathrm{H}\mathrm{e}+\gamma (5.5\mathrm{M}\mathrm{e}\mathrm{V})$ 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: $g_{Ae}\le (1.8-9.0)\times {10}^{-7}$. The solar positron flux from $A\to e^{-}+e^{+}$ 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: $g_{Ae} \leq (1-5)\times 10^{-17}$.