Measurement of the ²⁴⁰Pu/²³⁹Pu mass ratio using a transition-edge-sensor microcalorimeter for total decay energy spectroscopy

Journal Article · Fri Feb 27 00:00:00 EST 2015 · Analytical Chemistry

DOI:https://doi.org/10.1021/acs.analchem.5b00195· OSTI ID:1240404

Hoover, Andrew S. ^[1]; Bond, Evelyn M. ^[1]; Croce, Mark P. ^[1]; Holesinger, Terry G. ^[1]; Kunde, Gerd J. ^[1]; Rabin, Michael W. ^[1]; Wolfsberg, Laura E. ^[1]; Bennett, Douglas A. ^[2]; Hays-Wehle, James P. ^[2]; Schmidt, Dan R. ^[2]; Swetz, Daniel ^[2]; Ullom, Joel N. ^[2]

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1. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
2. National Institute of Standards and Technology, Boulder, CO (United States)

In this study, we have developed a new category of sensor for measurement of the ²⁴⁰Pu/²³⁹Pu mass ratio from aqueous solution samples with advantages over existing methods. Aqueous solution plutonium samples were evaporated and encapsulated inside of a gold foil absorber, and a superconducting transition-edge-sensor microcalorimeter detector was used to measure the total reaction energy (Q-value) of nuclear decays via heat generated when the energy is thermalized. Since all of the decay energy is contained in the absorber, we measure a single spectral peak for each isotope, resulting in a simple spectral analysis problem with minimal peak overlap. We found that mechanical kneading of the absorber dramatically improves spectral quality by reducing the size of radioactive inclusions within the absorber to scales below 50 nm such that decay products primarily interact with atoms of the host material. Due to the low noise performance of the microcalorimeter detector, energy resolution values of 1 keV fwhm (full width at half-maximum) at 5.5 MeV have been achieved, an order of magnitude improvement over α-spectroscopy with conventional silicon detectors. We measured the ²⁴⁰Pu/²³⁹Pu mass ratio of two samples and confirmed the results by comparison to mass spectrometry values. These results have implications for future measurements of trace samples of nuclear material.

• Research Organization: Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
• Sponsoring Organization: USDOE National Nuclear Security Administration (NNSA), Office of Defense Nuclear Nonproliferation
• Grant/Contract Number: AC52-06NA25396
• OSTI ID: 1240404
• Report Number(s): LA-UR-14-29014
• Journal Information: Analytical Chemistry, Vol. 87, Issue 7; ISSN 0003-2700
• Publisher: American Chemical Society (ACS)
• Country of Publication: United States
• Language: English

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46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY