  This works reports on gaseous detectors developments made in the frame of the
EXO double-beta decay experiment. LEM (Large Electron Multiplication) are
electron amplification grids based on GEM. They were developed in Neuchatel and
showed remarquable resistance to sparks. The new SILEM grid combines the
properties of the standard LEM with a micropatterned x-y readout plane on one
of the grid side. It allows thus the amplification of the primary electrons and
their position determination in the x-y plane.
