Search for 8.4-keV Solar Axions Emitted in the M1 Transition in 169Tm Nuclei.

Axions with an energy of 8.4 keV emitted in the М1 transition in ¹⁶⁹Tm nuclei in the Sun are sought in the → ¹⁶⁹Tm* → (8.4 keV) reaction of resonant absorption by ¹⁶⁹Tm nuclei on the Earth using a thulium garnet crystal as a bolometric detector. The flux of monochromatic 8.4‑keV axions has been calculated. New constraints on the axion–nucleon coupling constants have been obtained and, as a result, new upper bounds on the axion mass eV and eV have been obtained at 90% C.L. in the KSVZ and DFSZ models, respectively. [ABSTRACT FROM AUTHOR]