Discovery criteria

The following guidelines were used to determine the claim of discovery of a nuclide:

  • 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 discovery had to be reported in a refereed journal
  • The submission date is adopted as the date of discovery
  • In case two discovery articles were submitted on the same date, the article which was published first received the credit for the discovery
  • If the half-life was used as identification it had to agree with the later established half-life within about a factor of two

In most cases, the discovery is easy to determine. However, there are many cases that are controversial for many different reasons. To help resolve the controversial cases or to question an assignment, please email