  The aim of the presented work was to develop further techniques based on a
Micromegas-TPC, in order to reach a high gas gain with good energy resolution,
and to search for gas mixtures suitable for rare event detection. This paper
focuses on xenon, which is convenient for the search of neutrinoless double
beta decay in 136 Xe. Conversely, a small admixture of xenon to CF 4 can reduce
attachment in the latter. This gas mixture would be suitable for dark matter
searches and the study of solar and reactor neutrinos. Various configurations
of the Micromegas plane were investigated and are described.
