[en] The fission cross section of ²⁰⁹Bi induced by 14.7 MeV neutrons has been measured. Several Bi samples laminated between a mica backing and a mica detector were irradiated. The concentrations of uranium and thorium impurities of the samples are between 5 x 10^-4--3.5 x 10^-3 ppm. The cross section was measured relative to the reaction ²⁷Al(n,α) ²⁴Na. An upper limit of 1.6 x 10^-32 cm² was obtained

[en] The input data for an analysis of the s-process branching at ⁷⁹Se have been significantly improved. The neutron capture cross sections for the stable krypton isotopes (except ⁸⁶Kr) were measured between 3 and 240 keV neutron energy. In addition, statistical model calculations of the (n,γ)-cross sections for all isotopes involved in this branching were performed. With these data and with other experimental results from literature a recommended set of Maxwellian average cross sections was established in the mass region 77< A<85. The relevant decay parameters of the involved unstable nuclei and the parameters for the s-process model are discussed as well. On this basis the following aspects are investigated: the temperature during s-process, the decomposition into s- and r-process contributions and the solar krypton abundance. (orig.)

[en] Numerical results obtained from measurement of fragment properties in fast neutron induced fission of ²³⁵U and²³⁷Np are given in tabular form together with figures and a short description of the experiment. A detailed presentation of experiment and data analysis and the discussion of the results is in preparation. (orig.)

[en] Existing experimental and calculated neutron capture cross sections in the keV energy range have been surveyed, properly renormalized if necessary, and converted into Maxwellian averages over stellar neutron spectra characterized by thermal energies between 10 and 50 keV. This compilation includes all isotopes involved in the slow neutron capture process (s-process) of nucleosynthesis between ¹²C and /sup 209/Bi as well as the longer-lived actinide isotopes which might have been modified by the s-process. Gaps in the experimental data were covered with calculated cross sections, which are particularly important in the case of radioactive nuclei and for estimating the effect of thermally populated excited states. From the entire body of evaluated data a current best set of cross sections is recommended for use in s-process studies. copyright 1987 Academic Press, Inc

[en] The neutron capture cross sections of the stable krypton isotopes were determined in the energy interval from 4 to 250 keV using a C/sub 6/D/sub 6/-detector system in conjunction with the time-of-flight technique. The energy resolution of the measurement was 4% at 20 keV and 6% at 100 keV, and the experimental uncertainties were typically 6 to 10%. The measurements were complemented by statistical model calculations of all krypton isotopes in the mass range 78 < A < 86 to also obtain reliable cross sections for the unstable nuclei /sup 79,81,85/Kr. These calculations were based on local systematics for all relevant parameters, and the results were estimated to show uncertainties of 20 to 25%. Maxwellian average cross sections were calculated for kT=30 keV

[en] Published in summary form only

No abstract available

[en] The activation method is used to measure the stellar neutron capture rates of Re-185 and Re-187 at kT = 25 keV as 1677 + or - 65 and 1269 + or - 62 mbarn, respectively. The experimental setup and procedure are described, and the results are presented in tables and graphs. Also reported are calculations of the capture rates for the unstable isotopes, e.g., 597 + or - 85 mbarn for W-185 and 1775 + or - 265 mbarn for Re-186, again at kT = 25 keV. These results are then applied, using the classical method, to estimate the mean neutron density for the s-process nucleosynthesis branchings at W-185 and Re-186: n(n) = (4.1 + 1.2 or - 1.1) x 10 to the 8th/cu cm. 64 refs

No abstract available

[en] An updated table of Maxwellian averaged (n,γ) cross sections including the available information until December 1996 is illustrated at the example of ¹⁵³Eu. For the isotopes along the s-process reaction chain existing data were normalized if necessary, converted to stellar cross sections, and condensed into a set of recommended values for kT=30 keV. In a second step these recommended values were used to establish the stellar cross sections for thermal energies between 5 and 100 keV suited for all plausible s-process scenarios. (orig.)