/sup 186,187,188/Os(n,. gamma. ) cross sections and galactic nucleosynthesis

Journal Article · Fri Feb 01 04:00:00 EST 1980 · Phys. Rev., C; (United States)

DOI:https://doi.org/10.1103/PhysRevC.21.563· OSTI ID:5727378

Winters, R R; Macklin, R L; Halperin, J

The /sup 186,187,188/Os(n,..gamma..) cross sections were measured over the incident neutron energy range 2.6--800 keV. Optimized statistical model fits to the average cross sections were made employing estimates of the /sup 186/Os, /sup 187/Os, and /sup 188/Os p-wave strength functions 0.29 x 10/sup -4/, 0.45 x 10/sup -4/, and 0.33 x 10/sup -4/, respectively, d-wave strength functions 1.3 x 10/sup -4/, 4.0 x 10/sup -4/, and 1.5 x 10/sup -4/, respectively, and gamma ray strength functions (Gamma-bar/sub ..gamma..//D/sub 0/) 26.8 x 10/sup -4/, 176 x 10/sup -4/, and 20.8 x 10/sup -4/, respectively. A lower bound for the /sup 187/Os neutron inelastic cross section is estimated as 0.25(20) b at 30 keV. The Maxwellian-averaged capture cross sections are presented as a function of temperature. The ratio of 30 keV Maxwellian-averaged cross sections /=0.504(17) is reported and the lack of agreement with earlier measurements of this ratio is discussed. The use of this cross section ratio in estimating, via the /sup 187/Re-/sup 187/Os beta decay, the duration of galactic nucleosynthesis is discussed. The cross section ratio from this work yields an estimate of 10.4(25) x 10/sup 9/ yr for the duration of galactic nucleosynthesis, a result higher than but still consistent with the estimate 7(2) x 10/sup 9/ yr derived from U/Th decay.

• Research Organization: Physics Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830
• OSTI ID: 5727378
• Journal Information: Phys. Rev., C; (United States), Journal Name: Phys. Rev., C; (United States) Vol. 21:2; ISSN PRVCA
• Country of Publication: United States
• Language: English

Related Subjects

640105 -- Astrophysics & Cosmology-- Galaxies
651825* -- Nuclear Properties & Reactions
A=150-189
Experimental-- Nuclear Reactions & Scattering-- (-1987)
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
73 NUCLEAR PHYSICS AND RADIATION PHYSICS
BARYON REACTIONS
BETA DECAY
CAPTURE
COMPOUND NUCLEI
CROSS SECTIONS
DECAY
FUNCTIONS
GALAXIES
HADRON REACTIONS
INELASTIC SCATTERING
MATHEMATICAL MODELS
MONTE CARLO METHOD
NEUTRON REACTIONS
NUCLEAR REACTIONS
NUCLEON REACTIONS
NUCLEOSYNTHESIS
OSMIUM 186 TARGET
OSMIUM 187 TARGET
OSMIUM 188 TARGET
P WAVES
PARTIAL WAVES
SCATTERING
STATISTICAL MODELS
STRENGTH FUNCTIONS
TARGETS