New Constraints on the Axion–Electron Coupling Constant for Solar Axions

Abstract

The resonant excitation of the 83Kr first excited nuclear level (E = 9.4 keV) by solar axions whose fluxes depend on the axion–electron coupling constant gAe is sought. The γ- and X-ray photons and the conversion and Auger electrons from the excited-level relaxation are detected with a gas proportional counter of a low-background detector in the underground Baksan Neutrino Observatory (Institute for Nuclear Research, Russian Academy of Sciences). As a result, a new constraint $${\text{|}}{{g}_{{Ae}}}(g_{{AN}}^{3} - g_{{AN}}^{0}){\text{|}}$$ ≤ 1.50 × 10–17 (90% C.L.) has been obtained for the axion–electron and axion–nucleon coupling constants, which corresponds to new constraints on the axion mass mA ≤ 320 eV and mA ≤ 4.6 eV in the KSVZ and DFSZ axion models, respectively.