Using a spherical crystallite model with vacancies to relate local atomic structure to irradiation defects in ZrC and ZrN
Journal Article
·
· Journal of Nuclear Materials
- UW
- Research Organization:
- Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
- Sponsoring Organization:
- DOE - BASIC ENERGY SCIENCES
- OSTI ID:
- 1255287
- Journal Information:
- Journal of Nuclear Materials, Vol. 475, Issue 07, 2016; ISSN 0022-3115
- Country of Publication:
- United States
- Language:
- ENGLISH
Similar Records
Using a spherical crystallite model with vacancies to relate local atomic structure to irradiation defects in ZrC and ZrN
THERMAL EXPANSION AND ATOMIC VIBRATION AMPLITUDES FOR TiC, TiN, ZrC, ZrN, AND PURE TUNGSTEN
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
·
Fri Jul 01 00:00:00 EDT 2016
· Journal of Nuclear Materials
·
OSTI ID:1255287
+3 more
THERMAL EXPANSION AND ATOMIC VIBRATION AMPLITUDES FOR TiC, TiN, ZrC, ZrN, AND PURE TUNGSTEN
Journal Article
·
Wed Apr 01 00:00:00 EST 1964
· Phys. Chem. Solids
·
OSTI ID:1255287
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:1255287
+10 more