Fast neutron capture on the Hf isotopes: Cross sections, isomer production, and stellar aspects
- Forschungszentrum Karlsruhe, Institut fuer Kernphysik, Postfach 3640 D-76021 Karlsruhe (Germany)
The (n,{gamma}) cross sections of {sup 176}Hf, {sup 177}Hf, {sup 178}Hf, {sup 179}Hf, and {sup 180}Hf have been measured in the energy range from 3 to 225 keV relative to the gold standard. Neutrons were produced via the {sup 7}Li(p,n){sup 7}Be reaction and capture events were registered with the Karlsruhe 4{pi} barium fluoride detector. The overall uncertainties are between 0.9 and 2.6%, about 5 times smaller than in previous experiments. Partial cross sections to ground and isomeric states could be experimentally identified for neutron capture on {sup 176,177,178,179}Hf, indicating a strong population of yet-unknown isomeric states in {sup 177}Hf and {sup 180}Hf. This feature was confirmed by extensive GEANT simulations based on calculated capture cascades. The deduced Maxwellian-averaged (n,{gamma}) cross sections for thermal energies between kT=8 and 100 keV contribute to the analysis of the s-process branchings at A=176 and A=179/180 and have significant consequences for the separation of the solar s- and r-process components.
- OSTI ID:
- 20771501
- Journal Information:
- Physical Review. C, Nuclear Physics, Vol. 73, Issue 4; Other Information: DOI: 10.1103/PhysRevC.73.045807; (c) 2006 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 0556-2813
- Country of Publication:
- United States
- Language:
- English
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