New Micromegas detectors in the CAST experiment

A low background Micromegas detector was operating at the sunrise side of the CERN Axion Solar Telescope (CAST) experiment during the previous data taking periods (2002–2006). This detector, constructed of low radioactivity materials, operated efficiently and achieved a background level, 5×10-5keV-1cm-2s-1, in the 2–7 keV region. This performance was accomplished by exploiting the spatial and energy resolution of the detector as well as the time information contained in the pulse shape of the events. During the second phase of the experiment, the detector at the sunrise was replaced and upgraded by including a shielding. Moreover, the old time projection chamber (TPC) covering the sunset side of the experiment was replaced by two new Micromegas detectors. These detectors belong to the newest generation of Micromegas detectors: ‘bulk’ and ‘microbulk’. Performances and advantages will be presented.