A columnar cesium iodide (CsI) drift plane layer for gas avalanche microdetectors

A new method is proposed to improve the spatial and time resolutions, and the detection efficiency with respect to the angle of the incident particles, for gas avalanche micro detectors. The new technique uses a thin (/spl sim/200 /spl mu/m) columnar CsI layer at the drift plane that acts as an efficient source of electrons produced by secondary emission due to the incident particles, and as an electron multiplier. In this paper, we present the measurements of the electron multiplication factor and detection efficiency of this layer, using a /sup 90/Sr /spl beta/-source.