On April 24, 2008, a group led by Marinov at
Hebrew University of Jerusalem claimed to have found single atoms of
unbibium-292 in natural
thorium deposits at an abundance of 10−11 to 10−12 relative to thorium. The unbibium-292 atoms were claimed to be
superdeformed or
hyperdeformed nuclear isomers, with a half-life of at least 108 years. A criticism of the technique, previously used in purportedly identifying lighter
thorium isotopes by
mass spectrometry, was published in
Physical Review C in 2008. A rebuttal by the Marinov group was published in
Physical Review C after the published comment. A repeat of the thorium experiment using the superior method of
accelerator mass spectrometry (AMS) failed to confirm the results, despite a 100-fold better sensitivity. This result throws considerable doubt on the results of the Marinov collaboration with regards to their claims of long-lived isotopes of
thorium, and unbibium. It is still possible that traces of unbibium might exist in some thorium samples, though given current understanding of superheavy elements, this is very unlikely. == Family ==