New developments of Micromegas detector

A new type of micromesh, based on etching techniques, has been developed for the Micromegas detector. In this paper, we will briefly describe this new design and give some results about the performances obtained in different gas mixtures. The geometry of the mesh allows good uniformity of the electrostatic field. An energy resolution of 11.7 % full-width at half-maximum is obtained with X-rays at 5.9 keV and 5.4 % at 22 keV in an argon/isobutane (90%/10%) gas mixture. This is a significant improvement for a gaseous detector operating at high gain (about 5000).