Noble-gas operation of Micro-Hole and Strip Plate electron multipliers at atmospheric-to-high pressures

We present the performance of a Micro-Hole and Strip Plate (MHSP) electron multiplier in argon-xenon mixtures, at pressures of 1-7 bar. This microstructure can operate at high pressures without significant reduction of the maximum achievable gain. Absolute gains of 1-4x103 were reached in Ar/50 mbar Xe over this pressure range; the maximum gain is imposed by the discharge limit, dropping at higher pressures. Energy resolutions between 14% and 16% were reached for 6 keV X-rays; they do not degrade significantly with increasing pressure. Better performances are expected by improved manufacturing of the MHSP