Search

A low background Micromegas X-ray detector has been used to search for solar axions in the CAST experiment at CERN. The detector has an active area of 7cm times 7cm, excellent spatial resolution (~70nm), and good energy resolution. It is built using low radioactivity materials and the obtained background level is below 5times10-5 counts/keV/cm2/s. The detector is being upgraded for the second phase of the experiment (2006-2007) with a reduced active area. A focusing X-Ray optic and improved shielding will be used to further reduce the background by approximately two orders of magnitude.

A low background Micromegas detector has been operating on the CAST experiment at CERN for the search of solar axions during the first phase of the experiment (2002-2004). The detector operated efficiently and achieved a very low level of background rejection ($5\times 10^{-5}$ counts keV$^{-1}$cm$^{-2}$s$^{-1}$) thanks to its good spatial and energy resolution as well as the low radioactivity materials used in the construction of the detector. For the second phase of the experiment (2005-2007), the detector will be upgraded by adding a shielding and including focusing optics. These improvements should allow for a background rejection better than two orders of magnitude., 6 pages, 3 figures To appear on the proceedings of the 9th ICATPP Conference on AStroparticle, Particle, Space Physics, Detectors and Medical Physics Applications

The Micromegas technology can be used to construct very powerful detectors for low background, low energy measurements. A Micromegas X-ray detector has been used to search for solar axions in the CAST experiment at CERN. The detector has an active area of 7 cm × 7 cm, a very good x-y position, and a good energy resolution. It is built using low radioactivity materials and it is capable of low energy X-ray measurements of a few hundred eV. Despite the lack of external shielding the obtained background level is below 5 × 105 counts/keV/cm2/s. The detector is being upgraded with a reduced active area Micromegas module, a focusing X-Ray telescope and shielding, which are expected to further reduce the background by about two orders of magnitude.