Measurement of the ¹⁵⁴Gd(n,γ) cross section and its astrophysical implications

Abstract

The neutron capture cross section of ¹⁵⁴Gd was measured from 1 eV to 300 keV in the experimental area located 185 m from the CERN n_TOF neutron spallation source, using a metallic sample of gadolinium, enriched to 67% in ¹⁵⁴Gd. The capture measurement, performed with four C₆D₆ scintillation detectors, has been complemented by a transmission measurement performed at the GELINA time-of-flight facility (JRC-Geel), thus minimising the uncertainty related to sample composition. An accurate Maxwellian averaged capture cross section (MACS) was deduced over the temperature range of interest for s process nucleosynthesis modelling. We report a value of 880(50) mb for the MACS at $kT=30$ keV, significantly lower compared to values available in literature. The new adopted ¹⁵⁴Gd(n,γ) cross section reduces the discrepancy between observed and calculated solar s-only isotopic abundances predicted by s-process nucleosynthesis models.