Hypothetical axion-like particles with a two-photon interaction would be produced in the Sun by the Primakoff process. In a laboratory magnetic field (``axion helioscope\'\') they would
be transformed into X-rays with energies of a few keV. Using a decommissioned LHC test magnet, CAST has been running for about 6 months during 2003. The first results from the analysis of these
data are presented here. No signal above background was observed, implying an upper limit to the axion-photon coupling $g_{a\\gamma}
< 1.16 \\times 10^{-10}~{\\rm GeV}^{-1}$ at 95\\% CL for $m_a\\alt 0.02~{\\rm eV}$. This limit is comparable to the limit from stellar
energy-loss arguments and considerably more restrictive than any previous experiment in this axion mass range. |
