Beta-delayed fission and neutron emission calculations for the actinide cosmochronometers

Journal Article · Mon May 01 04:00:00 EDT 1989 · Phys. Rev. C; (United States)

DOI:https://doi.org/10.1103/PhysRevC.39.1876· OSTI ID:6068953

Meyer, B S; Howard, W M; Mathews, G J; Takahashi, K; Moeller, P; Leander, G A

The Gamow-Teller beta-strength distributions for 19 neutron-rich nuclei, including ten of interest for the production of the actinide cosmochronometers, are computed microscopically with a code that treats nuclear deformation explicitly. The strength distributions are then used to calculate the beta-delayed fission, neutron emission, and gamma deexcitation probabilities for these nuclei. Fission is treated both in the complete damping and WKB approximations for penetrabilities through the nuclear potential-energy surface. The resulting fission probabilities differ by factors of 2 to 3 or more from the results of previous calculations using microscopically computed beta-strength distributions around the region of greatest interest for production of the cosmochronometers. The indications are that a consistent treatment of nuclear deformation, fission barriers, and beta-strength functions is important in the calculation of delayed fission probabilities and the production of the actinide cosmochronometers. Since we show that the results are very sensitive to relatively small changes in model assumptions, large chronometric ages for the Galaxy based upon high beta-delayed fission probabilities derived from an inconsistent set of nuclear data calculations must be considered quite uncertain.

• Research Organization: Lawrence Livermore National Laboratory, Livermore, California 94550
• DOE Contract Number: W-7405-ENG-48
• OSTI ID: 6068953
• Journal Information: Phys. Rev. C; (United States), Journal Name: Phys. Rev. C; (United States) Vol. 39:5; ISSN PRVCA
• Country of Publication: United States
• Language: English

Related Subjects

640106* -- Astrophysics & Cosmology-- Cosmology
653006 -- Nuclear Theory-- Spontaneous & Induced Fission
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
73 NUCLEAR PHYSICS AND RADIATION PHYSICS
ACTINIDES
COSMOLOGY
DEFORMATION
ELEMENTS
ENERGY-LEVEL TRANSITIONS
FISSION
FUNCTIONS
GALAXIES
GAMOW-TELLER RULES
ISOTOPES
MATRIX ELEMENTS
METALS
NEUTRON-RICH ISOTOPES
NUCLEAR DEFORMATION
NUCLEAR REACTIONS
PROBABILITY
R PROCESS
RADIOISOTOPES
RANDOM PHASE APPROXIMATION
STAR EVOLUTION
STRENGTH FUNCTIONS
WKB APPROXIMATION