Abstract
Neutron-induced fission reactions play a crucial role in a variety of fields of fundamental and applied nuclear science. In basic nuclear physics they provide important information on properties of nuclear matter, while in nuclear technology they are at the basis of present and future reactor designs. Finally, there is a renewed interest in fission reactions in nuclear astrophysics due to the multi-messenger observation of neutron star mergers and the important role played by fission recycling in r-process nucleosynthesis. Although studied for several decades, many fundamental questions still remain on fission reactions, while modern applications and the development of more reliable nuclear models require high-accuracy and consistent experimental data on fission cross sections and other fission observables. To address these needs, an extensive fission research programme has been carried out at the n_TOF neutron time-of-flight facility at CERN during the last 18 years, taking advantage of the high energy resolution, high luminosity and wide energy range of the neutron beam, as well as of the detection and data acquisition systems designed for this purpose. While long-lived isotopes are studied on the 185 m long flight-path, the recent construction of a second experimental area at a distance of about 19 m has opened the way to challenging measurements of short-lived actinides. This article provides an overview of the n_TOF experimental programme on neutron-induced fission reactions along with the main characteristics of the facility, the various detection systems and data analysis techniques used. The most important results on several major and minor actinides obtained so far and the future perspectives of fission measurements at n_TOF are presented and discussed.
Highlights
Since its discovery in 1938, neutron-induced fission has been one of the most extensively studied nuclear reactions, being of great importance for a variety of fields in basic and applied nuclear science
There is a renewed interest in fission reactions in nuclear astrophysics due to the multi-messenger observation of neutron star mergers and the important role played by fission recycling in r -process nucleosynthesis
The main requests were related to the development of innovative systems for energy production and nuclear waste transmutation, in particular for accelerator-driven systems and Generation IV reactors, as well as for reactors based on the Th/U fuel cycle [1]
Summary
Since its discovery in 1938, neutron-induced fission has been one of the most extensively studied nuclear reactions, being of great importance for a variety of fields in basic and applied nuclear science. As we all learn from past experience, it may be beneficial for future studies, when new challenges will have to be faced, to discuss the experimental programme carried out in the last two decades at n_TOF. In this spirit, we have written this review paper, making it as comprehensive as possible of the many tasks involved in a successful fission measurement, from detector R&D to sample preparation, from signal reconstruction to data processing, from dead-time and pile-up corrections to Monte Carlo simulations. The main results of the n_TOF experimental programme obtained so far are presented in Sect. 6 and perspectives of a continuing programme are discussed at the end
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