Spherical optical model potential for the Re/Os stellar nucleosynthesis chronometer from s-italic-wave neutrons on /sup 186,187,188/Os

Journal Article · Mon Sep 01 00:00:00 EDT 1986 · Phys. Rev. C; (United States)

DOI:https://doi.org/10.1103/PhysRevC.34.840· OSTI ID:5386362

Winters, R R; Carlton, R F; Harvey, J A; Hill, N W

This paper reports resonance parameters and spherical optical model potentials obtained from the analyses of neutron transmission measurements for /sup 186,188/Os over the incident neutron energy range 27--1000 eV and for /sup 187/Os over the range 27--140 eV. Multilevel R-italic-matrix analyses of 77 s-italic-wave resonances yielded sets of resonance parameters (E-italic/sub lambda/,GAMMA/sub n/) and the associated external (background) R-italic functions. The statistical properties of the resonance parameters, mean-level spacings, and strength functions are reported. The external R-italic functions and strength functions were used to determine spherical optical model potential well depths, which in the case of /sup 187/Os we find to be strongly dependent on the spin of the compound nucleus. These optical model well depths can be used to estimate the capture cross section of the first excited state in /sup 187/Os+n. Since this state is highly populated at stellar temperatures, the ratio of excited to ground-state capture cross sections is an important parameter in using the s-italic-process model of stellar nucleosynthesis to determine what fraction of the abundance of /sup 187/Os should be ascribed to the radiogenic decay of /sup 187/Re. That fraction determines, in part, the estimate of the duration ..delta.. of stellar nucleosynthesis to be derived from /sup 187/Re beta decay. A determination of ..delta.. for the Re/Os chronometer based on our data leads to an age of the universe of (17 +- 3) x 10/sup 9/ yr.

• Research Organization: Department of Physics, Denison University, Granville, Ohio 43023
• OSTI ID: 5386362
• Journal Information: Phys. Rev. C; (United States), Vol. 34:3
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
73 NUCLEAR PHYSICS AND RADIATION PHYSICS
NEUTRON REACTIONS
CAPTURE
OSMIUM 186 TARGET
OSMIUM 187 TARGET
OSMIUM 188 TARGET
RHENIUM 187
BETA-MINUS DECAY
STARS
NUCLEOSYNTHESIS
COMPOUND-NUCLEUS REACTIONS
CROSS SECTIONS
ENERGY LEVELS
EV RANGE 10-100
EV RANGE 100-1000
HALF-LIFE
OPTICAL MODELS
R MATRIX
RESONANCE
S PROCESS
S WAVES
STRENGTH FUNCTIONS
UNIVERSE
BARYON REACTIONS
BETA DECAY
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
DECAY
ENERGY RANGE
EV RANGE
FUNCTIONS
HADRON REACTIONS
HEAVY NUCLEI
ISOTOPES
MATRICES
NUCLEAR REACTIONS
NUCLEI
NUCLEON REACTIONS
ODD-EVEN NUCLEI
PARTIAL WAVES
RADIOISOTOPES
RHENIUM ISOTOPES
STABLE ISOTOPES
STAR EVOLUTION
SYNTHESIS
TARGETS
YEARS LIVING RADIOISOTOPES
640102* - Astrophysics & Cosmology- Stars & Quasi-Stellar
Radio & X-Ray Sources
651825 - Nuclear Properties & Reactions
A=150-189
Experimental- Nuclear Reactions & Scattering- (-1987)
651822 - Nuclear Properties & Reactions
A=150-189
Experimental- Radioactive Decay- (-1987)