Nuclear physicists are seeking to synthesize ever heavier nuclei using nuclear fusion, which is in competition with quasifission reactions. Since fusion reactions are usually followed by a fission reaction, it is very difficult to differentiate them from quasifission reactions. This is why researchers are studying quasifission on its own, to better focus the search for super-heavy nuclei. 

The Franco-Australian team thus studied quasifission reactions induced by collisions between projectile ions of ⁴⁸Ti, accelerated to 276 MeV, and ²³⁸U target atoms. Their experiment at the Australian National University (ANU) accelerator in Canberra enabled them to identify, for the first time, the proton and neutron composition of the fragments created (up to 94 protons).

The researchers observed an intense production of nuclei around proton number 82 (lead), which corresponds to a so-called magic number for which the nuclei are particularly stable. This measurement reveals the very important role of quantum effects in quasifission reactions. These effects result in a layered organization of nucleons in the produced nuclei.