Search for Axion-like Particles from the Sun in an Underground Negative-Ion TPC

Abstract

Axion-like particles produced in the sun with masses in the keV range have been proposed to explain several long-standing anomalies in astrophysical X-ray observations. The gravitationally bound massive axions could be observed decaying to two X-ray photons in an instrumented underground detector volume. We propose to use a 1.5m 3 Negative-Ion TPC instrumented with GEM/Micromegas pad readout to perform a sensitive search for keV range axions. The sensitivity of the proposed experiment will be five orders of magnitude below existing limits after one year of running.