The scintillation of GEMS coated with wavelength shifters

Abstract

The optical readout of GEMs, presented a few years ago, is currently being considered for several detector projects. Although using suitable gaseous mixtures the GEM avalanches emit a large number of photons in the visible and/or NIR regions, many gaseous mixtures of great interest for detectors scintillate mainly in the UV, and the readout of these detectors is usually inefficient or very expensive. In this work we report on the operation of GEMs coated with a wavelength converter. We show that using a GEM with an optimal geometry the wavelength conversion process can be quite efficient and does not degrade the intrinsic position resolution of the detector, an usual drawback of the utilisation of wavelength shifters.