Tokyo Axion Helioscope

TL;DR

The Tokyo axion helioscope searches for solar axions by converting them into X-ray photons using a superconducting magnet and helium gas, setting new limits on axion-photon coupling for specific axion masses.

Contribution

This paper presents a new experimental setup and results that improve the limits on axion-photon coupling in the 0.84-1.0 eV mass range.

Findings

Set a new limit of g_{a\gamma\gamma}<(5.6--13.4)×10^{-10} GeV^{-1} for 0.84<m_a<1.0 eV

Used a cryogen-free 4T superconducting magnet with 2.3 m length

Enhanced conversion coherence with helium gas filling

Abstract

A new search result of the Tokyo axion helioscope is presented. The axion helioscope consists of a dedicated cryogen-free 4T superconducting magnet with an effective length of 2.3 m and PIN photodiodes as x-ray detectors. Solar axions, if exist, would be converted into X-ray photons through the inverse Primakoff process in the magnetic field. Conversion is coherently enhanced even for massive axions by filling the conversion region with helium gas. The present third phase measurement sets a new limit of g_{a\gamma\gamma}<(5.6--13.4)\times10^{-10} GeV^{-1} for the axion mass of 0.84<m_a<1.0 eV at 95% confidence level.