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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
DOE OSTI2015

{beta} decay of 129Cd and excited states in 129In

The β decay of Cd 129 , produced in the relativistic fission of a U 238 beam, was experimentally studied at the RIBF facility at the RIKEN Nishina Center. From the γ radiation emitted after the β decays, a level scheme of In 129 was established comprising 31 excited states and 69 γ -ray transitions. The experimentally determined level energies are compared to state-of-the-art shell-model calculations. The half-lives of the two β -decaying states in Cd 129 were deduced and the β feeding to excited states in In 129 were analyzed. It is found that, as in most cases in the Z<50 , N≤82 region, both decays are dominated by the ν0g 7/2 →π0g 9/2 Gamow–Teller transition, although the contribution of first-forbidden transitions cannot be neglected.

Taprogge, J.↗
DOE OSTI2019

Is an interacting ground state (pure state) v-representable density also non-interacting ground state v-representable by a Slater determinant? In the absence of degeneracy, yes!

It is shown that in the absence of degeneracy a density,$n,(r)$, describing the probability of finding a particle in a small volume at position, r, that is known to be pure-state v-representable in terms of the ground state of an interacting system of particles evolving under an external potential,$v,(r)$, is also pure state v-representable in terms of a single Slater determinant describing the ground state of a system of non-interacting particles under a potential, $v_s(r)$ . This establishes the validity of the Kohn–Sham formalism of density functional theory. An explicit form of $v_s(r)$ is derived. We also derive the exact form of the correlation functional and the corresponding potential, $\mu_c(r)$, that lead to the exact density and energy of an interacting system's ground state. In addition, we demonstrate the existence of a one-to-one mapping between the ground-state densities of non-degenerate interacting and non-interacting systems. Finally, we show that practical implementations of the Kohn–Sham formalism can generate neither the exact density nor energy of an interacting system's ground state, a feature that is particularly true in the case of the so-called exact exchange, in which the correlation functional and potential are set equal to zero.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2015

High-spin terminating states in the N = 88 Ho 155 and Er 156 isotones

Here, the 124 Sn( 37 Cl,6nγ) fusion-evaporation reaction at a bombarding energy of 180 MeV has been used to significantly extend the excitation level scheme of 155 67 Ho 88 . The collective rotational behavior of this nucleus breaks down above spin I ~ 30 and a fully aligned noncollective (band terminating) state has been identified at I π = 79/2 – . Comparison with cranked Nilsson–Strutinsky calculations also provides evidence for core-excited noncollective states at I π = 87/2 – and (89/2+) involving particle-hole excitations across the Z = 64 shell gap. A similar core-excited state in 156 68 Er 88 at I π = (46 + ) is also presented.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2018

Terminating states in the positive-parity structures of As67

The energy levels and γ-ray decay scheme of the positive-parity states in the Tz=12 nucleus 67As have been studied by using the 40Ca(36Ar,2αp)67As reaction at a beam energy of 145 MeV. Two new band structures have been identified which can be connected to the previously known levels. The results for these bands are compared with configuration-dependent cranked Nilsson–Strutinsky calculations. The good level of agreement between theory and experiment suggests that these structures can be interpreted in terms of configurations that involve three g92 particles and that both possess noncollective terminating states.

59 ≤ A ≤ 89↗
DOE OSTI2015

Solid-state syntheses and single-crystal characterizations of three tetravalent thorium and uranium silicates

Colorless crystals of ThSiO{sub 4} (huttonite) (1) and (Ca{sub 0.5}Na{sub 0.5}){sub 2}NaThSi{sub 8}O{sub 20} (2) have been synthesized by the solid-state reactions of ThO{sub 2}, CaSiO{sub 3}, and Na{sub 2}WO{sub 4} at 1073 K. Green crystals of (Ca{sub 0.5}Na{sub 0.5}){sub 2}NaUSi{sub 8}O{sub 20} (3) have been synthesized by the solid-state reactions of UO{sub 2}, CaSiO{sub 3}, and Na{sub 2}WO{sub 4} at 1003 K. All three compounds have been characterized by single-crystal X-ray diffraction. Compound 1 adopts a monazite-type three-dimensional condensed structure, which is built from edge- and corner-shared ThO{sub 9} polyhedra and SiO{sub 4} tetrahedra. Compounds 2 and 3 are isostructural and they crystallize in a steacyite-type structure. The structure consists of discrete pseudocubic [Si{sub 8}O{sub 20}]{sup 8−} polyanions, which are connected by An{sup 4+} cations into a three-dimensional framework. Each An atom coordinates to eight monodentate [Si{sub 8}O{sub 20}]{sup 8−} moieties in a square antiprismatic geometry. Na{sup +} and Ca{sup 2+} ions reside in the void within the framework. Raman spectra of 1, 2, and 3 were collected on single crystal samples. 1 displays more complex vibrational bands than thorite. Raman spectra of 2 and 3 are analogous with most of vibrational bands located at almost the same regions. - Graphical abstract: A Raman spectrum and crystal structures of (Ca{sub 0.5}Na{sub 0.5}){sub 2}NaAnSi{sub 8}O{sub 20} (An=Th, U), which contain pseudocubic [Si{sub 8}O{sub 20}]{sup 8−} polyanions and eight-coordinate An{sup 4+} cations. - Highlights: • Single crystal growth of three tetravalent actinide silicates from melts. • Single-crystal structures and Raman spectra of (Ca{sub 0.5}Na{sub 0.5}){sub 2}NaAnSi{sub 8}O{sub 20} (An=Th, U). • First report of Raman spectrum of huttonite on single crystal samples.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗