Speaker
Description
Optical TPCs, specially those operating in electroluminescence mode, are widely used in the searches for rare events, particularly in those involving the reconstruction of very faint energy deposits (down to single photon/electron sensitivity) or outstanding energy resolution.
Unlike avalanche multiplication, electroluminescence depends just on the maximum voltage that the structure can sustain, hence thick structures are preferable. In order to work in these conditions, a new type of very thick GEM ('FAT'-GEM) based on acrylic has been developed at CERN workshop. Acrylic is a rugged and homogeneous radio-pure material, easy to machine and widely available, therefore it holds some promise for a new generation of optimised structures in the field of rare event searches. First measurements under an Ar/Xe mixture at 10bar already showed an energy resolution extrapolating to 2%(FWHM) for the Qbb-energy of 136Xe, at an optical gain of around 1000ph/e. We will report in this contribution results of this ongoing effort, presenting results for a wide range of structures, gases and pressures.
