Deciphering Nb 98 β decay with the Modular Total Absorption Spectrometer at ORNL
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
- Univ. of Warsaw (Poland); Univ. of Tennessee, Knoxville, TN (United States)
- Univ. of Warsaw (Poland); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Univ. of Warsaw (Poland). Heavy Ion Lab.
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Univ. of Tennessee, Knoxville, TN (United States)
- Louisiana State Univ., Baton Rouge, LA (United States)
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Univ. of California, Berkeley, CA (United States)
- Univ. of Tennessee, Knoxville, TN (United States)
- Univ. of Tennessee, Knoxville, TN (United States); Univ. of Tennessee, Knoxville, TN (United States). Bredesen Center for Interdisciplinary Research and Graduate Education
- Univ. of Warsaw (Poland)
- Univ. of Tennessee, Knoxville, TN (United States); MKS Instruments, Inc., Rochester, NY (United States)
- Tennessee Technological Univ., Cookeville, TN (United States)
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Univ. of Tennessee, Knoxville, TN (United States); Chinese Academy of Sciences (CAS), Lanzhou (China). Inst. of Modern Physics
- Mississippi State Univ., Starkville, MS (United States)
An assessment done under the auspices of the Organization for Economic Co-operation and Developement Nuclear Energy Agency (OECD-NEA) in 2007 suggested that the β decays of many abundantly produced fission products in nuclear reactors may be incomplete. In this assessment, the fission product 98Nb was assigned the highest priority for study by total absorption spectroscopy due to its large cumulative fission branching fraction and because the β-decay data from several experiments are discrepant. To obtain the complete β-decay feeding pattern of 98Nb and determine the impact on the average γ energy per 98Nb β decay and v¯e emission calculations. The complete 98Nb β-decay feeding pattern includes ground-state to ground-state β feeding and direct β feeding to the 0+ first-excited state (both have no associated γ rays), and the ground-state to excited-state β transitions followed by γ transitions to the ground state of the daughter nucleus, 98Mo. The complete β-decay intensities of 98Nb were measured with the Modular Total Absorption Spectrometer at Oak Ridge National Laboratory (ORNL). Here, the 98Nb was produced by the β decay of mass 98 fission fragments at ORNL's On-Line Test Facility (OLTF) using proton-induced fission of 238U. We find that changes to the current ENSDF assessment of 98Nb β-decay intensity are required. We report improved uncertainties for the β-decay feeding values and report new β feedings to high-energy levels in 98Mo. A more complete 98Nb β-feeding pattern with improved accuracy and precision is offered. The impacts of the measured changes to the 98Nb β-feeding pattern on both reactor decay heat calculations and predicted detection rates of reactor v¯e are presented. The Modular Total Absorption Spectrometer measurements of 98Nb demonstrate the importance of reexamining and remeasuring complex β-decaying fission products with total absorption spectroscopy, including nuclei very near β stability.
- Research Organization:
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Nuclear Physics (NP); Polish National Centre for Science
- Grant/Contract Number:
- AC05-00OR22725; FG02-96ER40983; FG02-96ER40978; FG02-96ER41006; SC0016988; UMO-2016/23/B/ST2/03559
- OSTI ID:
- 1871884
- Journal Information:
- Physical Review. C, Vol. 105, Issue 6; ISSN 2469-9985
- Publisher:
- American Physical Society (APS)Copyright Statement
- Country of Publication:
- United States
- Language:
- English