Mitchell J. Myjak

Juvenile Salmon Acoustic Telemetry System Transmitter Downsize Assessment

At the request of the U.S. Army Corps of Engineers, Portland District, researchers from Pacific Northwest National Laboratory investigated the use of an application-specific integrated circuit (ASIC) to reduce the weight and volume of Juvenile Salmon Acoustic Telemetry System (JSATS) transmitters while retaining current functionality. Review of the design of current JSATS transmitters identified components that could be replaced by an ASIC while retaining the function of the current transmitter and offering opportunities to extend function if desired. ASIC design alternatives were identified that could meet transmitter weight and volume targets of 200 mg and 100 mm3. If alternatives to the cylindrical batteries used in current JSATS transmitters can be identified, it could be possible to implant ASIC-based JSATS transmitters by injection rather than surgery. Using criteria for the size of fish suitable for surgical implantation of current JSATS transmitters, it was concluded that fish as small as 70 mm in length could be implanted with an ASIC-based transmitter, particularly if implantation by injection became feasible.

Simulated Performance of the GammaTracker CdZnTe Handheld Radioisotope Identifier

Abstract-The GammaTracker handheld radioisotope identifier currently under development at the Pacific Northwest National Laboratory uses a pixellated CdZnTe spectrometer array to measure the energy and incoming direction of gamma rays from 50 keV to 3 MeV. This instrument, which incorporates the Polaris technology developed at the University of Michigan, houses two 3times3 arrays of 2.25-cm3 CdZnTe detectors. In this work, we present Geant4 simulation results of gamma-ray detection, identification, and directionality performance of the GammaTracker instrument. Estimated minimum detectable activities (MDAs) are determined to be only 20-30% higher than the MDAs predicted for a comparable-efficiency HPGe system over a reasonable energy range. The simulated imaging resolution is determined to be ~20deg FWHM, and the imaging efficiency is evaluated as a function of gamma-ray energy.