CAST (CERN Axion Solar Telescope) is a helioscope looking for axions coming from the solar core to the Earth. The experiment, located at CERN, is based on the Primakoff effect and uses a magnetic field of 9 Tesla provided by a decommissioned LHC magnet. CAST is able to follow the Sun during sunrise and sunset and therefore three X-ray detectors are mounted on both ends of the magnet waiting for a photon from axion-to-photon conversion due to the Primakoff effect. During its first phase, which concluded in 2004, CAST has been looking for axions with masses up to 0.02 eV. CAST’ s second phase manages to re-establish the coherence needed to scan for axions with masses up to 1.16 eV by using a buffer gas. This technique enables the experiment to look into the theoretical regions for axions. During the years 2005 and 2006, the use of 4He in CAST has already provided coherence in order to look for axions with masses up to 0.4 eV.