In this report, we present results of gain studies using various gas mixtur
es in a novel structure of gaseous detector called MICROMEGAS which is unde
r development at Saclay. We in particular studied the maximum of gain achie
vable with MICROMEGAS before the discharge. We tried various gas mixtures (
Argon, Neon, CF4) with various proportions of quencher (Isobutane, Cyclohex
ane, DME). We also studied the radiation hardness of MICROMEGAS using Argon
-Isobutane and CF4-Isobutane mixtures.