Tokyo axion helioscope experiment

TL;DR

This paper reports on an upgraded solar axion search experiment using an axion helioscope with enhanced capabilities to explore higher axion mass regions, setting new limits on axion-photon coupling.

Contribution

The experiment was upgraded to investigate higher axion masses (0.84-1.00 eV) using dispersion-matching gas, extending previous searches and setting new coupling limits.

Findings

No axion signal detected in the explored mass range.

Set upper limits on axion-photon coupling constant g < 5.6-13.4 x 10^{-10}/GeV.

Explored a previously unsearched axion mass region.

Abstract

A search for solar axions has been performed using an axion helioscope which is equipped with a 2.3m x 4T superconducting magnet, a gas container to hold dispersion-matching gas, PIN-photodiode X-ray detectors, and a telescope mount mechanism to track the sun. In the past measurements, axion mass up to 0.27eV have been scanned. It has been upgraded to handle dispersion-matching gas (He-4) of higher density to explore higher mass region. From December 2007 through April 2008, the axion mass region 0.84 < m < 1.00eV was newly explored, where the axions in the "photon-coupling vs. mass" parameter region of the preferred axion models were newly searched. From the absence of any evidence, a limit on axion-photon coupling constant was set to be g < 5.6-13.4e-10/GeV at 95% confidence level in the above mass region.