Advances In Microcalorimeter Gamma Spectroscopy

Year
2020
Author(s)
Mark Croce - Los Alamos National Laboratory, Los Alamos
Daniel Becker - University of Colorado, Boulder
Douglas Bennett - National Institute of Standards and Technology
Matthew Carpenter - Los Alamos National Laboratory, Los Alamos
Johnathon Gard - University of Colorado, Boulder
John A.B. Mates - University of Colorado, Boulder
David Mercer - Los Alamos National Laboratory, Los Alamos
Nathan Ortiz - University of Colorado, Boulder
Dan Schmidt - National Institute of Standards and Technology, Boulder, CO
Aidan Tollefson - Los Alamos National Laboratory, Los Alamos
Abigail Wessels - University of Colorado, Boulder
Michael Yoho - Los Alamos National Laboratory
Duc Vo - Los Alamos National Laboratory
Katrina Koehler - Los Alamos National Laboratory
Joel Ullom - National Institute of Standards and Technology
Abstract

Advances in both microcalorimeter instrumentation and data analysis are now making acquisition of high-quality spectra routine and enabling measurement campaigns on fuel cycle materials. With approximately 10 times better energy resolution than high-purity germanium detectors, ultra-high-resolution microcalorimeter gamma spectroscopy is intended to provide nondestructive isotopic analysis capabilities with sufficient precision and accuracy to reduce the need for sampling, chemical separations, and mass spectrometry to meet safeguards and security goals. A key milestone was the development of SOFIA (Spectrometer Optimized for Facility Integrated Applications), a compact microcalorimeter gamma spectrometer that combines advances in large multiplexed transition-edge sensor arrays with optimized cryogenic performance to overcome many practical limitations of previous instruments. A second instrument is now being built for deployment in an analytical laboratory later this year. We will present recent data from these instruments that is now being used to explore signatures of spent fuel and reprocessing, explore uncertainty limits of nondestructive uranium and plutonium isotopic characterization, inform safeguards models, and extract improved nuclear data including gamma-ray branching ratios.