Experimental HEP Seminar

First results from the CERN Axion Solar Telescope (CAST)

Marie Di Marco

Queen's University

The CERN Axion Solar Telescope (CAST) aims at the detection of the axion, a particle predicted by theory as a solution to the strong CP problem, and a well-motivated candidate for galactic dark matter. If axions exist, they could be copiously produced in the core of the sun, and convert into low-energy photons (~ 4.2 keV) when passing through a strong magnetic field, via the Primakoff process. The heart of CAST consists of a decommissioned 10m long LHC superconducting dipole prototype magnet, providing a magnetic field of up to 9.5 T. The X-rays produced by the conversion of solar axion are detected by 3 independent low background detectors (a TPC, a pn-CCD and a MicroMegas), installed on each end of the magnet. CAST has been taking data since May 2003, imposing an upper limit on the axion-photon coupling considerably more restrictive than any previous experiment in this axion mass range. In 2005, this limit will be further improved by filling the beam pipes with He3 gas, allowing to extend the sensitivity to a wider axion mass range. This talk will start with a brief introduction to axion physics, then focus on the technical aspects of the magnet and detectors, and finally present the first results of CAST, recently submitted to PRL for publication (arXiv:hep-ex/0411033).