Measurement of the 240Pu(n,f) cross-section at the CERN n-TOF facility: First results from experimental area II (EAR-2)

Abstract

The optimum design and development of advanced nuclear systems requires the accurate knowledge of neutron induced fission cross sections of plutonium isotopes and other minor actinides [1,2]. More specifically, the 240Pu isotope is included in the Nuclear Energy Agency’s (NEA) High Priority Request List (HPRL) [3] as well as in the NEMEA-4 meeting proceedings [4]. Requested target accuracies are in the order of 1.6%–11.8% for the energy region 0.454 keV–6.07 MeV compared to the presently reported 3.9%–21.6%. The previous experiment carried out at the n TOF’s Experimental Area 1 (EAR-1), was unsuccessful due to detector deterioration caused by the high alpha activity of the 240Pu samples in addition to the long period needed to complete the measurement [5], therefore the neutron induced fission cross section had to be remeasured in the newly constructed experimental area EAR-2, which offers a higher background suppression and a significantly higher instantaneous neutron flux, thus reducing the time needed to complete the measurement. Similar recent measurements have also been performed at GNEIS [6], LANSCE [7] and IRMM [8].