 This prompted many researchers to search for them in nature from 1976 to 1983.A group led by Tom Cahill, a professor at the University of California at Davis, claimed in 1976 that they had detected alpha particles and X-rays with the right energies to cause the damage observed, supporting the presence of these elements.In particular, the presence of long-lived (on the order of 109 years) unbiquadium and unbihexium nuclei, along with their decay products, at an abundance of 10−11 relative to their possible congeners uranium and plutonium, was conjectured.