S. K. Liu, Q. Yue, K. J. Kang et al.
Constraints on axion couplings from the CDEX-1 experiment at the China Jinping Underground Laboratory

Phys. Rev. D 95, 052006 (2017)

We report the results of searches for solar axions and galactic dark matter axions or axionlike particles with the CDEX-1 experiment at the China Jinping Underground Laboratory, using 335.6 kg days of data from a p-type point-contact germanium detector. The data are compatible with the background model, and no excess signals are observed. Limits of solar axions on the model-independent coupling g_Ae < 2.5 × 10⁻¹¹ from Compton, bremsstrahlung, atomic-recombination, and deexcitation channels and g^eff_AN × g_Ae < 6.4 × 10⁻¹⁷ from a ⁵⁷Fe M1 transition at 90% confidence level are derived. Within the framework of the Dine-Fischler-Srednicki-Zhitnitskiy and Kim-Shifman-Vainshtein-Zakharov models, our results exclude the axion mass heavier than 0.9 and 177 eV/c², respectively. The derived constraints for dark matter axions below 1 keV improve over the previous results.