The 12th IOPP Colloquium titled "Nuclear Fission as Brownian Motion" was delivered by Dr. Jørgen Randrup, a Senior Physicist (Emeritus) at the Lawrence Berkeley National Laboratory in the Institute of Particle Physics (IOPP), Central China Normal University on the morning of May 7, 2026.

Dr. Randrup began his talk with the quantum many-body dynamics of nuclear fission, systematically elaborating the theoretical framewo for the "Brownian Shape Evolution" developed by him and his collaborators. He pointed out that due to the strong dissipative nature of nuclear many-body systems, nuclear shape evolution resembles a Brownian motion. Based on this, he showcased the results from his simulation of the fission process using random walks on a five-dimensional potential energy surface, which successfully explains observables such as the fragment mass distributions, excitation energy partitioning, and angular momentum correlations. He also introduced novel applications of this theory in the r-process of  astrophysical nucleosynthesis and the formation of superheavy nuclei via fusion.

During the discussion session, Dr. Randrup engaged with young researchers from the intitute regarding the calculation of nuclear friction coefficients, microscopic level density corrections, and future collaborative research at C3NT (Central China Center for Nuclear Theory).

The IOPP Colloquium is a series of academic activities organized by the Institute of Particle Physics, aimed at fostering the academic ecosystem of the Institute. This talk demonstrated the deep integration of nuclear fission dynamics and statistical physics, providing a valuable learning opportunity for attendees and further reinforcing IOPP's academic characteristic of "international vision and interdisciplinary research."

Professor Xin-Nian Wang, Director of C3NT and IOPP, presented Dr. Jørgen Randrup with the 12th IOPP Colloquium Commemorative plaque

Dr. Jørgen Randrup is a Senior Physicist (now Emeritus) at the Lawrence Berkeley National Laboratory. He studied at the University of Aarhus in Denmark and received his PhD in 1972, after which he did postdoctoral research in Berkeley (LBNL) and Copenhagen (the Niels Bohr Institute and NORDITA), before taking up his career position at LBNL. He has worked on a range of topics, mostly related to nuclear collisions at various energies, including transport processes in damped nuclear reactions, equilibration and particle production in relativistic nuclear collisions, spinodal instabilities in multi-fragmentation, dynamics of disoriented chiral condensates, and phase structure of the strong interaction. In recent years, he has focused on dynamics of warm nuclei, with particular application to fission, for which he has developed the Brownian shape evolution treatment.

Group Photo of the 12th IOPP Colloquium

Correspondent: Xiangyu Shui
Proofreader: Xin-Nian Wang