Quantitative Analysis of Plutonium Content in Particles Collected from a Certified Reference Material by Total Nuclear Reaction Energy (Q Value) Spectroscopy

• Published in: Journal of low temperature physics Vol. 184; no. 3-4; pp. 938 - 943
• Main Authors: Croce, M. P., Hoover, A. S., Rabin, M. W., Bond, E. M., Wolfsberg, L. E., Schmidt, D. R., Ullom, J. N.
• Format: Journal Article
• Language: English
• Published: New York Springer US 01.08.2016; Plenum Press
• Subjects: Characterization and Evaluation of Materials; Condensed Matter Physics; Magnetic Materials; Magnetism; Physics; Physics and Astronomy; Plutonium particles; Microcalorimeter Q value spectroscopy
• ISSN: 0022-2291; 1573-7357
• DOI: 10.1007/s10909-016-1595-8

Microcalorimeters with embedded radioisotopes are an emerging category of sensor with advantages over existing methods for isotopic analysis of trace-level nuclear materials. For each nuclear decay, the energy of all decay products captured by the absorber (alpha particles, gamma rays, X-rays, electrons, daughter nuclei, etc.) is measured in one pulse. For alpha-decaying isotopes, this gives a measurement of the total nuclear reaction energy (Q value) and the spectra consist of well-separated, narrow peaks. We have demonstrated a simple mechanical alloying process to create an absorber structure consisting of a gold matrix with small inclusions of a radioactive sample. This absorber structure provides an optimized energy thermalization environment, resulting in high-resolution spectra with minimal tailing. We have applied this process to the analysis of particles collected from the surface of a plutonium metal certified reference material (CRM-126A from New Brunswick Laboratory) and demonstrated isotopic analysis by microcalorimeter Q value spectroscopy. Energy resolution from the Gaussian component of a Bortels function fit was 1.3 keV FWHM at 5244 keV. The collected particles were integrated directly into the detector absorber without any chemical processing. The 238 Pu/ 239 Pu and 240 Pu/ 239 Pu mass ratios were measured and the results confirmed against the certificate of analysis for the reference material. We also demonstrated inter-element analysis capability by measuring the 241 Am/ 239 Pu mass ratio.