Zhong He

Professor, Nuclear Engineering and Radiological Sciences
University of Michigan

Prof. Zhong He will discuss the Polaris γ-ray imaging spectrometer system composed of 3-dimensional position sensitive semiconductor radiation detectors. The original Polaris system is an 18-detector Cadmium Zinc Telluride (also known as CdZnTe or CZT) array system designed by the University of Michigan using analog readout electronics developed by Gamma Medica-Ideas, Inc. and detectors from Redlen Technologies, Inc. Each of the 18 detectors is cubic in shape with dimensions 20 mm × 20 mm × 15 mm. All system design and integration is performed by students and researchers in the Orion group. Data acquisition and analysis software is also written in house.

The original system built in 2010 achieved 1.5% FWHM at 662 keV for all events combined. The second system was built in June 2011 and achieved 1.2% FWHM at 662 keV for all events combined. The second-generation prototype system was built in 2012 in collaboration with H3D, Inc. (an Ann Arbor startup company employing several past Orion members) Brookhaven National Laboratory (developers of the next-generation analog readout electronics), and LocoLabs, LLC (responsible for rapid-prototype design of the integrated system). Due to improvements in the readout electronics, these systems achieve 0.9% FWHM at 662 keV for all events combined.

In addition to excellent energy resolution and room-temperature operation, the Polaris system provides source imaging in real time. Compton imaging is used for higher energy gamma rays in conjunction with a coded aperture for lower energy gamma rays.

This presentation will describe applications of 3D CZT imaging spectrometers for detecting and characterizing special nuclear materials (DOD, DEE, and DHS/DNDO applications), radiation safety in nuclear power plants (commercial), proton cancer therapy (NIH), planetary sciences (NASA), and fundamental physics.

Prof. He is part of the DoE supported Consortium for Verification Technology (CVT), consisting of thirteen leading universities, including Michigan and MIT, and eight national laboratories, which addresses technology and policy issues in treaty-compliance monitoring.