DATE2026.05.19 #Press Releases

Behind the Scenes of "Cosmic Alchemy" Explored by Newly Developed Lead Beam

Disclaimer: machine translated by DeepL which may contain errors.

New Discovery of 22 Rare Metal Isotopes

Summary 

A research group led by Naoki Fukuda, Shinichiro Michimasa, and Hiroshi Suzuki of the BigsRIPS Team at the RIKEN Nishina Center for Accelerator-Based Science (RIKEN), Nobuhisa Fukunishi, Group Leader of the Research Instruments Group,
and Hiroyoshi Sakurai, Director of the RIKEN Nishina Center, Assistant Professor Noritaka Kitamura, Associate Professor Daisuke Suzuki, and Associate Professor Nobuaki Imai of The University of Tokyo, has discovered 22 new isotopes of rare metals. The joint research group conducted experiments to produce radioisotopes (RIs) by colliding a newly developed lead beam with a target and shattering the nucleus (projectile fragmentation reactions) using the superconducting radioactive isotope beam separator BigRIPS at the RI Beam Factory (RIBF), the world's most powerful heavy-ion accelerator facility. A total of 22 new nuclei were discovered in the range from cerium (atomic number 58) to rhenium (atomic number 75), including 17 RIs with extremely high neutron abundance and 5 RIs with extremely high proton abundance.

Until now, the uranium beam with atomic number 92 has played a leading role in the production of heavy elements at the RIBF, but now the lead beam with atomic number 82 has proved to be extremely effective in the production of rare metal isotopes.
 This has paved the way for research to directly investigate RIs involved in the synthesis process from rare-earth elements to lead, which has long been a mystery in the synthesis of elements in the universe.

In particular, the same beam was successfully used to produce both extremely low and high neutron abundances of hafnium (atomic number 72) and tantalum (atomic number 73). This demonstrates that the use of a lead beam can dramatically accelerate studies of rare metal isotopes across a wide range of neutron numbers.

 Your body is made of elements forged in the universe. In the future, a vast new field of nuclear research will open up that goes behind the scenes of the "cosmic alchemy" of our roots, including the elucidation of the r and p processes that give rise to gold and platinum.

This research was published online in Progress of Theoretical and Experimental Physics on May 14.

"Map" showing the new isotopes found

Journal