Solar axion search with the CAST experiment

TL;DR

The CAST experiment searches for solar axions by converting them into photons within a strong magnetic field, setting new experimental limits on axion-photon coupling and upgrading for higher mass sensitivity.

Contribution

This paper reports the first results with helium-4 and system upgrades enabling sensitivity to higher axion masses in the CAST experiment.

Findings

Most restrictive limit on axion-photon coupling from initial vacuum phase

First results from helium-4 data taking

Upcoming sensitivity estimates for helium-3 phase

Abstract

The CAST (CERN Axion Solar Telescope) experiment is searching for solar axions by their conversion into photons inside the magnet pipe of an LHC dipole. The analysis of the data recorded during the first phase of the experiment with vacuum in the magnet pipes has resulted in the most restrictive experimental limit on the coupling constant of axions to photons. In the second phase, CAST is operating with a buffer gas inside the magnet pipes in order to extent the sensitivity of the experiment to higher axion masses. We will present the first results on the $^{4}{\rm He}$ data taking as well as the system upgrades that have been operated in the last year in order to adapt the experiment for the $^{3}{\rm He}$ data taking. Expected sensitivities on the coupling constant of axions to photons will be given for the recent $^{3}{\rm He}$ run just started in March 2008.