Search for solar axions emitted in an M1 transition in 7Li* nuclei

Abstract

The resonance absorption of solar axions by 7Li nuclei, which is accompanied by the excitation of the first nuclear level of lithium a + 7Li → 7Li* → 7Li + γ, is sought. To this end, the energy spectrum has been measured by an HPGe detector that is surrounded by a LiOH layer. A new upper limit ma ≤ 16 keV (at 90% C.L.) has been determined for the mass of the hadron axion.