image: The projectiles generate the extremely neutron-rich fragments through either single-step or multi-step reaction, with the latter involving one or more intermediate nuclei.
Credit: Bao-Hua Sun
New Approach Enhances Yields of Most Neutron-Rich Isotopes
Researchers from Beihang University and the Institute of Modern Physics (CAS) have proposed a novel strategy to increase production of exotic nuclei near the neutron drip line. By leveraging multi-step fragmentation of high-energy beams (~1 GeV/nucleon) in thick targets (~3 mean free paths), this approach effectively enhances the production of neutron-rich fragments. Unlike conventional single-step fragmentation, it enhances yields of extremely neutron-rich residues by several orders of magnitude, thereby overcoming the intrinsic limitations imposed by low cross sections.
Validating Multi-Step Fragmentation in Realistic Scenarios
Thick-target reactions inevitably increase the transverse emittance and momentum spread of the beam due to cumulative scattering and fragmentation. To quantify this effect, researchers performed simulations using the future HIRIBL beamline at China’s HIAF facility under commissioning, focusing on the transmission efficiency of the fragments. Results confirm that despite broader momentum distributions, multi-step fragmentation still dramatically outperforms single-step methods, enhancing the production of neutron-rich isotopes enough to open access to previously unexplored regions of the nuclear chart.
Scientific Implications and Future Applications
This framework transcends conventional fragmentation techniques by integrating complementary reactions, such as projectile fission coupled with fragmentation, to optimize isotope production. These modular strategies provide unprecedented flexibility to reach drip-line nuclei and investigating their exotic structures. Critically, the resulting access to these isotopes promises transformative advances in nuclear astrophysics—elucidating the composition of neutron star crusts and refining models of r-process nucleosynthesis, the cosmic pathway responsible for creating heavy elements like gold and uranium.
The complete study is accessible via Doi: https://doi.org/10.1007/s41365-025-01785-2
https://link.springer.com/article/10.1007/s41365-025-01785-2
Journal
Nuclear Science and Techniques
Method of Research
Computational simulation/modeling
Subject of Research
Not applicable
Article Title
Searching for nuclei on the edge of stability with multi-step fragmentation
Article Publication Date
5-Aug-2025