High-resolution gamma ray detector for process tomography

We developed a high-resolution gamma ray detection system and associated fast read-out electronics to image rapidly rotating multi-phase distributions in stirred chemical reactors and hydrodynamic machines. The detector arc is made of 320 small scintillation detector elements comprising LYSO scintillation crystals with an active area of 2 mm times 8 mm coupled to large area avalanche photodiodes. Pulse processing electronics is made of charge sensitive preamplifier, pulse shaper, gain adjustable amplifier, energy discrimination stage, and binary pulse counters. The counter stage is implemented in FPGA architecture. For fast measurements on rotating objects a fast read-out scheme with 6 bit counter depth and 40 mus read-out interval has been implemented. This enables acquisition of 500 full radiographic projections of objects rotating at 3000 rpm.