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. 


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.

Articles related to the project are posted on the publications page.


FRIB will continue to update the project and post the most recent new discoveries here.

Rankings and Search

Tables of the top authors, laboratories, countries, and journals are listed here. With the search feature, one can also look up the isotopes discovered by a specific author, or at specific laboratory and country.

Clickable chart of Nuclides

FRIB collaborates with the National Nuclear Data Center (NNDC) at Brookhaven National Laboratory and the abstract for an isotope displays in the NuDat Chart of Nuclides when the specific isotopes is clicked. 

Comments and updates

If someone is aware of discoveries not yet listed or would like to comment on a specific assignment, please email
If you would like to receive notifications about new isotope discovery papers, please email


The discovery of isotopes database is a json file and available to download here.