Two-dimensional readout of GEM detectors

Abstract

The recently introduced Gas Electron Multiplier (GEM) permits the amplification of electrons released by ionizing radiation in a gas by factors approaching ten thousand; larger gains can be obtained combining two GEMs in cascade. We describe methods for implementing two-and three-dimensional projective localization of radiation, with sub-millimeter accuracy, making use of specially manufactured and patterned pick-up electrodes. Easy to implement and flexible in the choice of the readout geometry, the technology has the distinctive advantage of allowing all pick-up electrodes to be kept at ground potential, thus substantially improving the system simplicity and reliability. Preliminary results demonstrating the two-dimensional imaging capability of the devices are provided and discussed, as well as future perspectives of development.

Recent advances in X-ray detection with micro-hole and strip plate detector

“…It was demonstrated that a micro-strip gas counter (MSGC) [2] preceded by a GEM has higher gain and stability compared to the MSGC alone [3]. Localization can be obtained in GEM detectors by coupling a properly patterned readout anode to a GEM [4]. Very high multiplication factors, exceeding 10 6 -10 7 , have been measured with single photoelectrons in gas-avalanche photomultipliers combining a photocathode and cascaded GEM structures [5].…”

Gas detectors: achievements and trends

“…Most of the electrons in the avalanche move into the lower gap and are collected; effective gains well above several thousand can be achieved, sufficient for detection of minimum ionizing tracks in thin conversion layers [30]. Localization can then be performed collecting the charge on a patterned one-or two-dimensional readout board [31]. A unique feature of GEM detectors is that proportional multiplication and charge detection are performed on separate electrodes; with proper choice of the operating conditions one can effectively avoid the propagation of discharges to the sensitive electronics.…”

“…Further use of the technology demands the development of faster dedicated read-out electronics. To avoid the reconstruction ambiguities in case of multiple events, we have developed the 3-D projective readout scheme described in previous work [31]. In the socalled hexaboard detector, the readout plane is patterned with contiguous hexagonal pads interconnected in rows along three directions 2 (Fig.…”

Gas electron multiplier (GEM) detectors for an advanced x-ray monitor

“…gain factors of 10 4 ), so that the readout tracks could collect the charge without operating at high voltage. 13 GEM technology has been successful in achieving this goal in both double-GEM and GEM + MSGC configurations. These detectors are successfully used outside of CERN (e.g.…”