The CAST experiment: status and perspectives

TL;DR

The CAST experiment searches for solar axions using a magnet and buffer gases, setting upper limits on axion-photon coupling and exploring higher mass ranges with ongoing and future phases.

Contribution

This paper reports on the status, results, and future perspectives of the CERN Axion Solar Telescope (CAST) in searching for solar axions across different mass ranges.

Findings

Set an upper limit on axion-photon coupling of g < 2.17 x 10^10 GeV$^{-1}$ for axion masses below 0.4 eV.

Conducted a search for axions up to 1.2 eV using 3He buffer gas, with ongoing analysis.

Discussed future sensitivities and long-term plans for a new helioscope experiment.

Abstract

The status of the solar axion search with the CERN Axion Solar Telescope (CAST) will be discussed. Results from the first part of CAST phase II where the magnet bores were filled with 4He gas at variable pressure in order to scan axion masses up to 0.4 eV will be presented. From the absence of excess X-rays when the magnet was pointing to the Sun, we set a typical upper limit on the axion-photon coupling of g < 2.17 x 10^10 GeV$-1 at 95% CL for axion masses lower than 0.4 eV, the exact result depending on the pressure setting. Our search for axions with masses up to about 1.2 eV using 3He as a buffer gas is in progress in the second part of CAST phase II. Expectations for sensibilities will be given. Near future perspectives as well as more long term options for a new helioscope experiment will be evoked.