High Impact: Search for solar axions via axion-photon coupling with the Majorana Demonstrator

Axions were originally proposed to explain the strong-𝐶⁢𝑃 problem in QCD. Through axion-photon coupling, the Sun could be a major source of axions, which could be measured in solid state detection experiments with enhancements due to coherent Primakoff-Bragg scattering. The Majorana Demonstrator experiment has searched for solar axions with a set of ⁷⁶Ge-enriched high purity germanium detectors using a 33 kg-yr exposure collected between January, 2017 and November, 2019. A temporal-energy analysis gives a new limit on the axion-photon coupling as 𝑔_𝑎⁢𝛾<1.45×10^-9  GeV−1 (95% confidence level) for axions with mass up to 100  eV/𝑐². This improves laboratory-based limits between about 1  eV/𝑐² and 100  eV/𝑐².