Discovery of Nuclides Project
Discovery of Nuclides Project
At the core of each atom is the atomic nucleus (also called nuclide), which consists of neutrons and protons. The number of protons defines the chemical element (for example 6 for carbon and 8 for oxygen). Each element can contain different number of neutrons; these different types of nuclides of an element are called isotopes. The Discovery of Nuclides Project documents the discovery of all isotopes.
Background
In 2007, Professor Michael Thoennessen and a group of undergraduate students began to document the discovery of all isotopes. In contrast to the discovery of a new element, the first observation of a new isotope is not as well defined.
For each isotope, they wrote a brief paragraph describing the discovery, including the authors, institution, year, and method of discovery. The paragraph included a quote from the original paper and discussed any possible controversies related to the discovery.
These paragraphs were published in a series of papers in the journal Atomic Data and Nuclear Data Tables. The table of the discovery papers lists links to the references for each element. In 2015, a major revision which applied the discovery criteria consistently across the chart of nuclei was published in the book The Discovery of Isotopes. Since then, a few additional reassignments and corrections were made.
Learn about the most recent isotope discoveries on the latest discovered isotopes page, and find articles related to the project posted on the publications page. In 2025, the database was extended to include the discovery of nuclear isomers, which are two or more metastable states within the same isotope.
Discovery of isotopes
Isotopes are variants of a chemical element that have the same number of protons (atomic number) but different numbers of neutrons.
Discovery of isomers
Nuclear isomers are excited states in nuclides with finite lifetimes.
News
FRIB will continue to update the project and post the most recent new nuclide discoveries here.
Comments and updates
If someone is aware of discoveries not yet listed or would like to comment on a specific assignment, please email nuclides@frib.msu.edu.
If you would like to receive notifications about new isotope discovery papers, please email nuclides@frib.msu.edu.
Learn more about how this work is supported by the U.S. Department of Energy, Office of Nuclear Physics.
Isotopes are variants of a chemical element that have the same number of protons (atomic number) but different numbers of neutrons.
Nuclear isomers are excited states in nuclides with finite lifetimes. In analogy to chemical isomers, which are the same compounds with distinct structures, nuclear isomers have the same number of protons and neutrons but in different configurations.
The most recent discoveries of new isotopes are displayed here. These isotopes are added to the database after the references are entered in the Nuclear Science References database.
The original papers describing the discovery of the isotopes of all elements were published over several years in the journal Atomic Data and Nuclear Data Tables (ADNDT).
Browse a list of publications related to the Discovery of Nuclides Project.
