Resonance capture cross section of 207 Pb

Abstract

The radiative neutron capture cross section of 207 Pb has been measured at the CERN neutron time of flight installation n TOF using the pulse height weighting technique in the resolved energy region. The measurement has been performed with an optimized setup of two C6D6 scintillation detectors, which allowed us to reduce scattered neutron backgrounds down to a negligible level. Resonance parameters and radiative kernels have been determined for 16 resonances by means of an R-matrix analysis in the neutron energy range from 3 keV to 320 keV. Good agreement with previous measurements was found at low neutron energies, whereas substantial discrepancies appear beyond 45 keV. With the present results, we obtain an s -process contribution of 77±8% to the solar abundance of 207 Pb. This corresponds to an r-process component of 23±8%, which is important forderiving the U/Th ages of metal poor halo stars.