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Table of radioactive elements

Description: As has been the custom in the past, the Commission publishes a table of relative atomic masses and halflives of selected radionuclides. The information contained in this table will enable the user to calculate the atomic weight for radioactive materials with a variety of isotopic compositions. The atomic masses have been taken from the 1984 Atomic Mass Table. Some of the halflives have already been documented.
Date: January 1, 1985
Creator: Holden, Norman E.
Partner: UNT Libraries Government Documents Department
open access

Determination of thorium and uranium at the nanogram per gram level in semiconductor potting plastics by neutron activation analysis

Description: A method was developed to determine thorium and uranium in semiconductor potting plastics. The method is based on neutron activation and subsequent radiochemical separation to isolate and permit measurement of the induced /sup 233/Pa and /sup 239/Np. These plastics typically contain macro amounts of silicon, bromine and antimony and nanogram per gram amounts of thorium and uranium. The radiochemical method provides the necessary sensitivity and makes it possible to easily attain adequate decont… more
Date: January 1, 1985
Creator: Dyer, F.F.; Emery, J.F. & Bate, L.C.
Partner: UNT Libraries Government Documents Department
open access

Octupole Correlations in the Heavy Elements

Description: The effects of octupole correlations on the nuclear structure of the heavy elements are discussed. The cluster model description of the heavy elements is analyzed. The relevance of 2/sup 6/-pole deformation and fast El transitions to an octupole model is considered. 30 refs., 21 figs., 1 tab.
Date: January 1, 1986
Creator: Chasman, R. R.
Partner: UNT Libraries Government Documents Department
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Neutron scattering cross sections for /sup 232/Th and /sup 238/U inferred from proton scattering and charge exchange measurements. [7 MeV, 26 and 27 MeV]

Description: Differential cross sections for the (p,n) reactions to the isobaric analog states (IAS) of /sup 232/Th and /sup 238/U targets were measured at 26 and 27 MeV. The analysis of the data was done in conjunction with the proton elastic and inelastic (2/sup +/, 4/sup +/, 6/sup +/) differential cross sections measured at 26 MeV. Because collective effects are important in this mass region, deformed coupled-channels calculations were carried out for the simultaneous analysis of the proton and neutron o… more
Date: January 1, 1980
Creator: Hansen, L. F.; Grimes, S. M.; Pohl, B. A.; Poppe, C. H. & Wong, C.
Partner: UNT Libraries Government Documents Department
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Synthesis and characterization of Pa(IV), Np(IV), and Pu(IV) borohydrides

Description: The actinide borohydrides of Pa, Np, and Pu have been prepared and some of their physical and optical properties measured. X-ray powder diffraction photographs of Pa(BH/sub 4/)/sub 4/ have shown that it is isostructural to Th(BH/sub 4/)/sub 4/ and U(BH/sub 4/)/sub 4/. Np(BH/sub 4/)/sub 4/ and Pu(BH/sub 4/)/sub 4/ are much more volatile than the borohydrides of Th, Pa, and U and are liquids at room temperature. Results from low-temperature single-crystal x-ray diffraction investigation of Np(BH/… more
Date: December 1, 1979
Creator: Banks, R.H. & Edelstein, N.M.
Partner: UNT Libraries Government Documents Department
open access

Gamma-ray line intensities for depleted uranium

Description: Measurements of the gamma-ray line intensities from depleted uranium allowed us to determine which of two conflicting previous experiments was correct. For the 1001-keV line we obtain a branching ratio of 0.834 +- 0.007, in good agreement with one of the previous experiments. A table compares our intensities for several lines with those obtained in previous experiments. 5 refs., 2 figs., 1 tab.
Date: January 1, 1985
Creator: Moss, C.E.
Partner: UNT Libraries Government Documents Department
open access

Spectroscopic and magnetic studies of tetravalent Pa and trivalent Th compounds

Description: At the beginning of the actinide series, the 5f and 6d configurations are very close in energy. Consequently, both the 5f and 6d energy level splittings may be observed experimentally in Pa{sup 4+} and Th{sup 3+} compounds. The available magnetic and optical data on these systems are reviewed.
Date: June 1, 1992
Creator: Edelstein, N.M. & Kot, W.K.
Partner: UNT Libraries Government Documents Department
open access

Shell effects on the E1 moments of Ra-Th nuclei

Description: Large systematic shell effects on intrinsic E1 moments are found, which should modulate any E1 moment induced by ..beta../sub 3/ deformation. The calculated shell effects can explain an emerging trend for E1 data in Ra-Th nuclei, if and only if the gross ..beta../sub 3/-induced polarization of finite nuclear matter goes in the same direction as the lightning rod effect. 16 references.
Date: January 1, 1984
Creator: Leander, G.A.
Partner: UNT Libraries Government Documents Department
open access

Octupole correlation effects in nuclei

Description: Octupole correlation effects in nuclei are discussed from the point of view of many-body wavefunctions as well as mean-field methods. The light actinides, where octupole effects are largest, are considered in detail. Comparisons of theory and experiment are made for energy splittings of parity doublets; E1 transition matrix elements and one-nucleon transfer reactions.
Date: August 1, 1992
Creator: Chasman, R. R.
Partner: UNT Libraries Government Documents Department
open access

Resonance enhancement in the accelerator transmutation of 1.3-day {sup 232}Pa and 2.1-day {sup 238}Np

Description: The suggestion that the transmutation of actinide waste into fission products might best be done with thermalized spallation neutrons and odd-odd target materials such as {sup 238}Np has been studied. During the 1993 LAMPF/PSR cycle, we measured the fission cross section of 1.3-day {sup 232}Pa and 2.1-day {sup 238}Np from 0.01 eV to 40 keV at the LANSCE facility, and have carried out a preliminary resonance analysis of the observed structure and of the thermal region, with a 1/v representation … more
Date: August 1, 1994
Creator: Moore, M. S. & Danon, Y.
Partner: UNT Libraries Government Documents Department
open access

Octupole correlation effects in nuclei

Description: Octupole correlation effects in nuclei are discussed from the point of view of many-body wavefunctions as well as mean-field methods. The light actinides, where octupole effects are largest, are considered in detail. Comparisons of theory and experiment are made for energy splittings of parity doublets; E1 transition matrix elements and one-nucleon transfer reactions.
Date: January 1, 1992
Creator: Chasman, R. R.
Partner: UNT Libraries Government Documents Department
open access

Forecast of Standard Atomic Weights for the Mononuclidic Elements – 2011

Description: In this short report, I will provide an early warning about potential changes to the standard atomic weight values for the twenty mononuclidic and the so-called pseudo-mononuclidic ({sup 232}Th and {sup 231}Pa) chemical elements due to the estimated changes in the mass values to be published in the next Atomic Mass Tables within the next two years. There have been many new measurements of atomic masses, since the last published Atomic Mass Table. The Atomic Mass Data Center has released an unpu… more
Date: July 27, 2011
Creator: Holden, N. E.; Holden, N. & Holden, N. E.
Partner: UNT Libraries Government Documents Department
open access

Development of a technique for measuring cross sections of interest to accelerator transmutation of waste (ATW)

Description: It has been suggested that transmutation of actinide waste into fission products could be enhanced by using resonance fission of odd-odd target materials; those of interest are {sup 232}Pa, {sup 238}Np, and {sup 242}Am. Our technique for carrying out the measurement of the resonance fission cross section of short-lived materials has three steps: (1) We produce the sample by the (d,2n) reaction at the Los Alamos Ion Beam Facility. (2) We carry out fast radiochemistry to separate the odd-odd targ… more
Date: May 1, 1994
Creator: Moore, M. S.; Koehler, P. E. & Littleton, P. E.
Partner: UNT Libraries Government Documents Department
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Gas-phase energies of actinide oxides -- an assessment of neutral and cationic monoxides and dioxides from thorium to curium

Description: An assessment of the gas-phase energetics of neutral and singly and doubly charged cationic actinide monoxides and dioxides of thorium, protactinium, uranium, neptunium, plutonium, americium, and curium is presented. A consistent set of metal-oxygen bond dissociation enthalpies, ionization energies, and enthalpies of formation, including new or revised values, is proposed, mainly based on recent experimental data and on correlations with the electronic energetics of the atoms or cations and wit… more
Date: August 10, 2009
Creator: Marcalo, Joaquim & Gibson, John K.
Partner: UNT Libraries Government Documents Department
open access

Influence of 5f electrons on structure and bonding in the actinide-hydrogen intermetallics

Description: Complexa phases form for the Th + H and U + H systems that are found with no other metals. In the Pa + H system, simple bcc C15 Laves and A15 phases can form, dependent on temperature and composition. The phase transformations appear to b magnetically driven, as a resutl of the decoupling of the metallic 5f electron bonding that occurs during hydriding; the C15 phases contain two kinds of Pa atoms-the one sublattice being still fully f-bonded and the other magnetic. This is a unique situation i… more
Date: January 1, 1984
Creator: Ward, J.W.
Partner: UNT Libraries Government Documents Department
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Reflection asymmetry in odd-A and odd-odd actinium nuclei

Description: Theoretical calculations and measurements indicate that octupole correlations are at a maximum in the ground states of the odd-proton nuclei Ac and Pa. It has been expected that odd-odd nuclei should have even larger amount of octupole-octupole correlations. We have recently made measurements on the structure of {sup 224}Ac. Although spin and parity assignments could not be made, two bands starting at 354.1 and 360.0 keV have properties characteristic of reflection asymmetric shape. These two b… more
Date: September 1, 1993
Creator: Ahmad, I.
Partner: UNT Libraries Government Documents Department
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Spectroscopic and magnetic studies of tetravalent Pa and trivalent Th compounds

Description: At the beginning of the actinide series, the 5f and 6d configurations are very close in energy. Consequently, both the 5f and 6d energy level splittings may be observed experimentally in Pa{sup 4+} and Th{sup 3+} compounds. The available magnetic and optical data on these systems are reviewed.
Date: June 1, 1992
Creator: Edelstein, N. M. & Kot, W. K.
Partner: UNT Libraries Government Documents Department
open access

High resolution measurement of the /sup 231/Pa(n,f) cross section from 0. 4 eV to 12 MeV

Description: The /sup 231/Pa(n,f) reaction was studied to shed light on the existence of a shallow third minimum in the /sup 232/Pa fission barrier. Results are plotted along with data points derived from ENDF/B-V. The occurrence of a pure vibrational state at E/sub n/ = 156.7 keV (3/sup +/) together with a nearby state of opposite parity favors the evidence for a third asymmetrically deformed minimum in the /sup 232/Pa fission barrier. 2 figures. (RWR)
Date: January 1, 1980
Creator: Plattard, S.; Auchampaugh, G. F. & de Saussure, G.
Partner: UNT Libraries Government Documents Department
open access

High-resolution fission cross section of /sup 231/Pa. [0. 1 to 12 MeV and 0. 4 eV to 10 keV]

Description: A high resolution fission cross section for /sup 231/Pa was measured at ORELA from 0.1 to 12 MeV and between 0.4 eV and 10 keV. The data show evidence for (1) fractionated vibrational structures in the threshold region of the fission cross section, and (2) narrow fisson resonances above 1.3 eV with an average fission width < GAMMA/sub f/ > = 8 ..mu..eV. 16 references.
Date: January 1, 1979
Creator: Plattard, S.; Auchampaugh, G. F.; Hill, N. W.; de Saussure, G.; Perez, R. B. & Harvey, J. A.
Partner: UNT Libraries Government Documents Department
open access

High-resolution fission cross section of /sup 231/Pa. [0. 4 eV to 12 MeV]

Description: The /sup 231/Pa fission cross section was measured with high resolution at OREA from 0.1 to 12 MeV and between 0.4 eV and 10 keV. The data show evidence for fractionated vibrational structures in the threshold region of the fission cross section, and narrow fission resonances above 0.4 eV with an average fission width < GAMMA/sub f/ > = 8 ..mu..eV. 3 figures, 3 tables.
Date: January 1, 1979
Creator: Plattard, S.; Auchampaugh, G. F.; Hill, N. W.; de Saussure, G.; Perez, R. B. & Harvey, J. A.
Partner: UNT Libraries Government Documents Department
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