Einsteinium was first identified in December 1952 by Albert Ghiorso and co-workers at the University of California, Berkeley in collaboration with the Argonne and Los Alamos National Laboratories, in the fallout from the "Ivy Mike" nuclear test. The test was carried out on November 1, 1952, at Enewetak Atoll in the Pacific Ocean and was the first successful test of a hydrogen bomb. Initial examination of the debris from the explosion had shown the production of a new isotope of plutonium, , which could only have formed by the absorption of six neutrons by a uranium-238 nucleus followed by two beta decays.