Novel Technique for Developing Linearized Convex System Models from Experimentally Derived Data
Conference
·
OSTI ID:1561840
- National Renewable Energy Laboratory (NREL), Golden, CO (United States)
This poster provides an overview of a novel technique for developing linearized convex system models from experimentally derived data.
- Research Organization:
- National Renewable Energy Lab. (NREL), Golden, CO (United States)
- Sponsoring Organization:
- New Energy and Industrial Technology Development Organization (NEDO), Japan
- DOE Contract Number:
- AC36-08GO28308
- OSTI ID:
- 1561840
- Report Number(s):
- NREL/PO-5D00-74510
- Resource Relation:
- Conference: Presented at the 2019 IEEE Power and Energy Society General Meeting, 4-8 August 2019, Atlanta, Georgia
- Country of Publication:
- United States
- Language:
- English
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Novel Technique for Developing Linearized Convex System Models from Experimentally Derived Data
Novel Technique for Developing Linearized Convex System Models from Experimentally Derived Data: Preprint
Most theoretical approaches used in nuclear astrophysics to model the nucleosynthesis of heavy elements incorporate the so-called statistical model in order to describe the excitation and decay properties of atomic nuclei. One of the basic assumptions of this model is the validity of the Brink–Axel hypothesis and the related concept of so-called photon strength functions to describe γ-ray transition probabilities. We present a novel experimental approach that allows for the first time to experimentally determine the photon strength function simultaneously in two independent ways by a unique combination of quasi-monochromatic photon beams and a newly implemented γ–γ coincidence setup. This technique does not assume a priori the validity of the Brink–Axel hypothesis and sets a benchmark in terms of the detection sensitivity for measuring decay properties of photo-excited states below the neutron separation energy. The data for the spherical off-shell nucleus 128Te were obtained for γ-ray beam-energy settings between 3 MeV and 9 MeV in steps of 130 keV for the lower beam energies and in steps of up to 280 keV for the highest beam settings. We present a quantitative analysis on the consistency of the derived photon strength function with the Brink–Axel hypothesis. The data clearly demonstrate a discrepancy of up to a factor of two between the photon strength functions extracted from the photoabsorption and photon emission process, respectively. In addition, we observe that the photon strength functions are not independent of the excitation energy, as usually assumed. Thus, we conclude, that the Brink–Axel hypothesis is not strictly fulfilled in the excitation-energy region below the neutron separation threshold (Sn = 8.78 MeV) for the studied case of 128Te.
Conference
·
Thu Jan 30 00:00:00 EST 2020
·
OSTI ID:1561840
Novel Technique for Developing Linearized Convex System Models from Experimentally Derived Data: Preprint
Conference
·
Thu Oct 24 00:00:00 EDT 2019
·
OSTI ID:1561840
Most theoretical approaches used in nuclear astrophysics to model the nucleosynthesis of heavy elements incorporate the so-called statistical model in order to describe the excitation and decay properties of atomic nuclei. One of the basic assumptions of this model is the validity of the Brink–Axel hypothesis and the related concept of so-called photon strength functions to describe γ-ray transition probabilities. We present a novel experimental approach that allows for the first time to experimentally determine the photon strength function simultaneously in two independent ways by a unique combination of quasi-monochromatic photon beams and a newly implemented γ–γ coincidence setup. This technique does not assume a priori the validity of the Brink–Axel hypothesis and sets a benchmark in terms of the detection sensitivity for measuring decay properties of photo-excited states below the neutron separation energy. The data for the spherical off-shell nucleus 128Te were obtained for γ-ray beam-energy settings between 3 MeV and 9 MeV in steps of 130 keV for the lower beam energies and in steps of up to 280 keV for the highest beam settings. We present a quantitative analysis on the consistency of the derived photon strength function with the Brink–Axel hypothesis. The data clearly demonstrate a discrepancy of up to a factor of two between the photon strength functions extracted from the photoabsorption and photon emission process, respectively. In addition, we observe that the photon strength functions are not independent of the excitation energy, as usually assumed. Thus, we conclude, that the Brink–Axel hypothesis is not strictly fulfilled in the excitation-energy region below the neutron separation threshold (Sn = 8.78 MeV) for the studied case of 128Te.
Journal Article
·
Tue Jan 01 00:00:00 EST 2019
· Physics Letters B
·
OSTI ID:1561840
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