Progress of experimental research on neutron-induced charged-particle emission nuclear reactions

Nuclear fission and fusion are the primary means for nuclear energy release. In both processes, the interaction between neutrons and atomic nuclei—that is, neutron-induced nuclear reactions—is involved. Neutrons, being electrically neutral, can easily induce various types of nuclear reactions. The level of experimental measurement capabilities for nuclear reactions serves as an important reflection of a country’s scientific and technological strength. Peking University and the Joint Institute for Nuclear Research (JINR) in Dubna have signed a protocol on “Carrying out Joint Studies on the Mechanism of Interaction of Neutrons with Nuclei and on the Properties of Highly Excited Nuclear States”, which has been renewed multiple times and remains in effect at present. For over three decades, experimental and theoretical studies have been performed on neutron-induced light charged particle emission nuclear reactions (n, lcp) in a range of light, medium-mass, and heavy nuclei. These investigations were carried out using neutron sources including the 4.5 MV van de Graaff accelerator at Peking University, the EG-5 van de Graaff accelerator at JINR, the Beijing HI-13 tandem accelerator neutron source, and the China Spallation Neutron Source Back-n white neutron source (CSNS Back-n), etc. In recent years, the experimental research has expanded from neutron-induced light charged particle emission reactions (n, lcp) to fission reactions (n, f) of heavy nuclei. The charged particle detectors employed include the grid ionization chamber (GIC), light charged particle detector array (LPDA), diamond detector, and multi-purpose time projection chamber (MTPC). Over the years, our team has continuously upgraded experimental facilities, refined research methodologies, improved measurement accuracy, expanded domestic and international collaborations, and extended neutron energy ranges for measurements. Up to now, 68 nuclear reactions and 128 sets of nuclear reaction data measured or contributed to by our team have been included in the international experimental nuclear reaction database, EXFOR. In this database, our laboratory is assigned the code “CPRBJG” where “CPR” stands for “China” and “BJG” represents “Peking University”. More than 150 papers were published in domestic and international academic journals. Through Sino-Russian collaboration, we have supervised over 20 master’s and doctoral students in obtaining their degrees. Dr Yury Gledenov, an expert of the Frank Laboratory of Neutron Physics at the Joint Institute for Nuclear Research, who has collaborated with our team for over 30 years and visited China 26 times for joint experimental research, was awarded the 2023 Chinese Government Friendship Award. This paper reviews the developmental trajectory of the joint research related to neutron-induced charged particle emission reactions (n, cp), encompassing both neutron-induced light charged particle nuclear reactions (n, lcp) and fission reactions (n, f), highlights key achievements, and provides an outlook on future developments.