β- and γ-Counting for Pre-detonation Nuclear Forensics on Eu-155
Post-detonation nuclear forensics was performed at Los Alamos National Laboratory (LANL) on 155Eu, a fission product on the wing of the fission product production curve whose yield is sensitive to fission fuel and neutron energy. With a half-life of 4.753 years, 155Eu provides a longer-lived option for these measurements than other fission products with similar mass numbers. The Chemistry Division Group - Nuclear and Radiochemistry, at LANL routinely measures a suite of fission products from 235U fissions in thermal neutron flux experiments known as thermal calibration exercises, using a mixture of gas proportional β-decay counting and γ-spectrometry on HPGe detectors. The fission products of interest are reported relative to a high-yield reference fission product from the same sample to create a running average ratio specific to neutron energy and fuel type; Equation 1 below shows the ratio-of-ratios R-value measured fission products are reported in: Rix = [A(iX)/A(99Mo)]unknown[A(iX)/A(99Mo)]235Un,th where A denotes activity, iX is the nuclide of interest, and 235Un,th denotes irradiations of 235U with thermal neutrons. Measurements of unknown fission spectra are ratioed to a running-average of thermal calibration results, and the resulting R-value can be referred to as against a library of irradiation conditions.
- Research Organization:
- Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
- Sponsoring Organization:
- USDOD; USDOE National Nuclear Security Administration (NNSA)
- DOE Contract Number:
- 89233218CNA000001
- OSTI ID:
- 1993194
- Report Number(s):
- LA-UR-23-28541; TRN: US2404593
- Country of Publication:
- United States
- Language:
- English
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