NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT, vol.471, no.1-2, pp.151-155, 2001 (SCI-Expanded)
At the Karolinska Institute in Stockholm, Sweden a new detector for portal imaging is under development, which could greatly improve the alignment of the radiation beam with respect to the tumor during radiation treatment. The detector is based on solid converters combined with gas electron multipliers (GEMs) as an amplification structure. The detector has a large area and will be operated in a very high rate environment in the presence of heavy ionizing particles. As was discovered recently high rates and alpha particles could cause discharges in GEM and discharge propagation from GEM to GEM and to the readout electronics. Since reliability is one of the main requirements for the portal imaging device, we performed systematic studies to find a safe operating range of the device, free from typical high rate problems, such as discharges. (C) 2001 Elsevier Science B.V. All rights reserved.