Status report of the Tokyo axion helioscope experiment

TL;DR

This paper reports on the status of the Tokyo axion helioscope experiment, which searches for solar axions using a superconducting magnet and X-ray detectors, setting upper limits on axion-photon coupling and preparing for future searches in higher mass regions.

Contribution

It provides the latest results and status update of the Tokyo axion helioscope, including upper limits on axion-photon coupling and plans for exploring higher axion masses.

Findings

No positive axion detection in the 0 to 0.27 eV mass range.

Set upper limit on axion-photon coupling constant to g < 6-10E-10/GeV.

Preparing for future experiments targeting axions with masses of one to a few eV.

Abstract

We have searched for solar axions with a detector which consists of a 4T x 2.3m superconducting magnet, PIN-photodiode X-ray detectors, and an altazimuth mount to track the sun. The conversion region is filled with cold helium gas which modifies the axion mass at which coherent conversion occurs. In the past measurements, axion mass from 0 to 0.27eV have been scanned. Since no positive evidence was seen, an upper limit to the axion-photon coupling constant was set to be g < 6-10E-10/GeV (95%CL) depending on the axion masses. We are now actively preparing for a new stage of the experiment aiming at one to a few eV solar axions. In this mass region, our detector might be able to check parameter regions which are preferable to the axion models.