Neutron induced fission cross-section of 240Pu(n,f): first results from n_TOF (CERN) Experimental Area II

The accurate knowledge of neutron cross-sections of a variety of plutonium isotopes and other minor actinides, such as neptunium, americium and curium, is crucial for feasibility and performance studies of advanced nuclear systems (Generation-IV reactors, Accelerator Driven Systems). In this context, the 240Pu(n,f) cross-section was measured with the time-of-flight technique at the CERN n_TOF facility at incident neutron energies ranging from thermal to several MeV. The present measurement is the first to have been performed at n_TOF's newly commissioned Experimental Area II (EAR-2), which is located at the end of an 18m neutron beam-line and features a neutron fluence that is 25-30 times higher with respect to the existing 185m flight-path (EAR-1), as well as stronger suppression of sample-induced backgrounds, due to the shorter times-of-flight involved. Preliminary results are presented

First

Most elements heavier than iron have been generated in the stellar media by means of neutron capture reactions, approximately half are produced by the slow neutron capture or s-process. Radiative neutron capture cross section measurements are of fundamental importance for the study of this mechanism. In this contribution we present a brief summary on the measurement and results for the 80Se(n,γ) cross-section. The experiment was carried out at CERN n_TOF EAR1 via the time of flight (ToF) technique, using four C6D6 scintillation detectors with very fast response. More than a hundred new resonances have been analyzed for the first time with a high accuracy. The MACS obtained at kT = 8 keV is 36% smaller than the recommended value in KADo-NiS. Some of the astrophysical implications of this result are elucidated in this contribution