A search for bremsstrahlung solar axions using the Majorana low-background BEGe detector at Kimballton (MALBEK)

TL;DR

This study uses a specialized germanium detector to search for solar axions produced via bremsstrahlung, setting new limits on axion-electron coupling and exploring detection prospects through annual modulation signals.

Contribution

It provides the first experimental upper bound on DFSZ axion-electron coupling using low-background germanium detectors and discusses future sensitivity improvements.

Findings

Upper bound of $1.36\times 10^{-11}$ on axion-electron coupling

Detection prospects via seasonal modulation signals

Potential for improved sensitivity with future detectors

Abstract

A low-background, high-purity germanium detector has been used to search for evidence of low-energy, bremsstrahlung-generated solar axions. An upper bound of $1.36\times 10^{-11}$ $(95% CL)$ is placed on the direct coupling of DFSZ model axions to electrons. The prospects for the sensitivity of the Majorana Demonstrator array of point-contact germanium detectors to solar axions are discussed in the context of the model-independent annual modulation due to the seasonal variation of the earth-sun distance.