The neutron capture cross section of Pb-206 has been measured at the CERN n_TOF spectrometer using a setup of two C6D6 detectors. In the energy interval from 1 eV to 600 keV the cross section is dominated by resonances, which were analyzed via the R-matrix analysis code SAMMY. In the relevant energy ranges for stellar nucleosynthesis, i. e., at thermal energies of kT = 8 keV and kT = 23 keV, the present Maxwellian average cross section differs by 20% and 9% from the recommended values of Bao et al respectively. From the new cross section the s-abundance of Pb-206 could be reliably determined as 70( 4)%. This result is of importance in order to test and constrain r-process abundance calculations in the actinide region, because the r-process portion of Pb-206 is dominated by alpha-back decays of short-lived transbismuth isotopes.
The measurement of the Pb-206(n,gamma) cross section and stellar implications
BISTERZO, SARA;FERRARI, Attilio;GALLINO, Roberto;
2008-01-01
Abstract
The neutron capture cross section of Pb-206 has been measured at the CERN n_TOF spectrometer using a setup of two C6D6 detectors. In the energy interval from 1 eV to 600 keV the cross section is dominated by resonances, which were analyzed via the R-matrix analysis code SAMMY. In the relevant energy ranges for stellar nucleosynthesis, i. e., at thermal energies of kT = 8 keV and kT = 23 keV, the present Maxwellian average cross section differs by 20% and 9% from the recommended values of Bao et al respectively. From the new cross section the s-abundance of Pb-206 could be reliably determined as 70( 4)%. This result is of importance in order to test and constrain r-process abundance calculations in the actinide region, because the r-process portion of Pb-206 is dominated by alpha-back decays of short-lived transbismuth isotopes.
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