Progress in the measurement of the neutron-induced fission cross-section at CSNS Back-n

Abstract

The China Spallation Neutron Source (CSNS) is a newly constructed large-scale facility located in Dongguan, which was completed and operational in 2018. It is generating neutrons by bombarding 1.6 GeV protons into a tungsten target for multidisciplinary research. A back-streaming neutron beamline (Back-n) at CSNS is built at the reverse direction opposite to the proton beam mainly for the nuclear data measurement. Back-n is characterized by its wide energy range (from 0.3 eV to 300 MeV), high flux (~107 n/cm2/s at 55 m) and good energy resolution (less than 1% below 1 MeV), standing as one of the state-of-the-art white neutron beams worldwide. Fission cross-sections of a series of nuclei, such as 235, 236, 238U, 232Th, 239Pu have been measured in wide energy ranges since 2018, and more isotopes (such as minor actinides) are planned to be measured in the near future. The CSNS Back-n facility and the progress in the fission cross-section measurements are reviewed in this paper. Then the prospects of the fission cross-section measurement at Back-n are discussed.