ASTROPHYSICAL NEUTRON CAPTURE RATES IN s– AND r–PROCESS NUCLEOSYNTHESIS
نویسنده
چکیده
Astrophysical neutron capture rates of light and heavy nuclei have been measured and calculated. For the measurements the activation technique was applied at the 3.75 MV Karlsruhe Van de Graaff accelerator, and at the Geel electron linear accelerator (GELINA) the time–of–flight (TOF) method was used. The calculations were performed using direct and compound nuclear capture models.
منابع مشابه
Direct neutron captures and the r-process nucleosynthesis
The radiative direct capture of neutrons is calculated within the potential model. The uncertainties related to the choice of the neutron-nucleus interaction potential and the prediction of the excitation spectrum in the residual nucleus are discussed. The allowed direct E1-type transitions to all the excited states predicted by a combinatorial model of nuclear level densities are calculated wi...
متن کاملR-process Abundance Signatures
Abundance observations indicate the presence of rapid-neutron capture (i.e., rprocess) elements in old Galactic halo and globular cluster stars. These observations demonstrate that the earliest generations of stars in the Galaxy, responsible for neutron-capture synthesis and the progenitors of the halo stars, were rapidly evolving. Abundance comparisons among large numbers of stars provide clue...
متن کاملTheoretical Neutron-capture Cross Sections for R-process Nucleosynthesis in the 48ca Region
We calculate neutron capture cross sections for r-process nucleosynthesis in the 48 Ca region, namely for the isotopes 40?44 S, 46?50 Ar, 56?66 Ti, 62?68 Cr, and 72?76 Fe. While previously only cross sections resulting from the compound nucleus reaction mechanism (Hauser-Feshbach) have been considered, we recalculate not only that contribution to the cross section but also include direct captur...
متن کاملar X iv : a st ro - p h / 02 10 12 5 v 1 4 O ct 2 00 2 1 Observations of Neutron - Capture Elements in the Early Galaxy
Neutron-capture elements in low metallicity Galactic halo stars vary widely both in overall contents and detailed abundance patterns. This review discusses recent observational results on the n-capture elements, discussing the implications for early Galactic nucleosynthesis of: (a) the star-to-star " bulk " variations in the n-capture/Fe abundance ratios; (b) the distinct signature of rapid n-c...
متن کاملGeneral properties of astrophysical reaction rates in explosive nucleosynthesis
Fundamental differences in the prediction of reaction rates with intermediate and heavy target nuclei compared to the ones with light nuclei are discussed, with special emphasis on stellar modifications of the rates. Ground and excited state contributions to the stellar rates are quantified, deriving a linear weighting of excited state contributions despite of a Boltzmann population of the nucl...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
عنوان ژورنال:
دوره شماره
صفحات -
تاریخ انتشار 1997