Improved plutonium and americium photon branching ratios from microcalorimeter gamma spectroscopy

• Published in: Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment Vol. 977; p. 164307
• Main Authors: Yoho, M.D., Koehler, K.E., Becker, D.T., Bennett, D.A., Carpenter, M.H., Croce, M.P., Gard, J.D., Mates, J.A.B., Mercer, D.J., Ortiz, N.J., Schmidt, D.R., Smith, C.M., Swetz, D.S., Tollefson, A.D., Ullom, J.N., Vale, L.R., Wessels, A.L., Vo, D.T.
• Format: Journal Article
• Language: English
• Published: United States Elsevier B.V 11.10.2020; Elsevier
• Subjects: Americium; Branching ratios; INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; Microcalorimeter; Non-destructive assay; Plutonium; Transition edge sensor; Microcalorimeter; Transition edge sensor; Americium; Plutonium; Branching ratios; Non-destructive assay
• ISSN: 0168-9002; 1872-9576
• DOI: 10.1016/j.nima.2020.164307

Photon branching ratios are critical input data for activities such as nuclear materials protection and accounting because they allow material compositions to be extracted from measurements of gamma-ray intensities. Uncertainties in these branching ratios are often a limiting source of uncertainty in composition determination. Here, we use high statistics, high resolution (̃60–70 eV full-width-at-half-maximum at 100 keV) gamma-ray spectra acquired using microcalorimeter sensors to substantially reduce the uncertainties for 11 plutonium (238Pu, 239Pu, 241Pu) and 241Am branching ratios important for material control and accountability and nuclear forensics in the energy range of 125 keV to 208 keV. We show a reduction in uncertainty of over a factor of three for one branching ratio and a factor of 2–3 for four branching ratios.