Discovery of Nuclides Project
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.
Search for isomer discoveries
Search by element, author, laboratory, and more.
Discovery criteria
The following guidelines were used to determine the claim of discovery of an isomer:
- Half-lives of more than 100 ns
- Clean identification, either by decay curves (half-lives) and relationships to other known isotopes, particle or γ-ray spectra, or unique mass and Z identification
- The metastability of the isomer had to be measured, which in most cases was the half-life
- The discovery had to be reported in a refereed journal
- The submission date is adopted as the date of discovery
- If only a lower half-life limit was reported, the decay energy had to be determined
- If the discovery of an isotope involved the observation of only one state which could have been the ground state or an isomer, the subsequent observation of a second state−either the ground state or an isomer−is counted as the discovery of isomerism
In most cases, the discovery is easy to determine. However, there are cases that are controversial for many different reasons. To help resolve the controversial cases or to question an assignment, please email nuclides@frib.msu.edu.
Downloads
The discovery of isomers database is a json file and available to download 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 or isomer discovery papers, please email nuclides@frib.msu.edu.
Discovery of Nuclides Project
Visit the main page to access a complete list of sections and resources.
