Artificial radioactive element properties unknown	memory peg
	1952 Albert Ghiorso and co-workers, Berkeley, Calif., USA
	Albert Einstein (1879-1955)

First prepared in 1952 by Albert Ghiorso, Stanley G. Thompson, Gary H. Higgins, Glenn T. Seaborg (from the Radiation Laboratory and Department of Chemistry of the University of California), Martin H. Studier, P.R. Fields, Sherman M. Fried, H. Diamond, J.F. Mech, G.L. Pyle, John R. Huizenga, A. Hirsch, W.M. Manning (from the Argonne National Laboratory), C.I. Browne, H. Louise Smith, and R.W. Spence (from the Los Alamos Scientific Laboratory) by irradation of Uranium with neutrons. Element #99 was, together with Fermium discovered unexpectedly in the debris from the thermonuclear explosion (called the "Mike" event), conducted at Eniwetok Atoll in the Pacific Ocean in November 1952.

Codiscoverers of Einsteinium (1952) and Fermium (1953) at symposium commemorating the 25th anniversary of their discovery held at the LBL. Left to right (front row): Louise Smith, Sherman Fried, Gary Higgins. Left to right (back row): Albert Ghiorso, Rod Spence, Glenn Seaborg, Paul Fields and John Huizenga. [caption according to Seaborg 1996, the list of names does not agree with the list given by Seaborg in 1973].

The Materials Testing Reactor in Idaho came into operation during 1952, and provided a neutron flux an order of magnitude higher than previously available. At the same time, techniques for accelerating useful beams of heavy ions were being developed in several laboratories. These developments ensured the eventual synthesis of elements #99 and #100, but the first observation of these elements came unexpectedly, from a quite unrelated experiment - the explosion of the first thermonuclear bomb in the Pacific during November 1952.

Samples of debris were collected by drone aircraft flying through the cloud and analyzed. Among the new activities detected were alpha-emitters of 6.6 and 7.1 MeV, indicating that a brief exposition to a very high neutron flux can have similar results to the slow irradiation by heavy elements made on the labs in Idaho. From the analysis of these samples it was possible to identify the source of the alpha particles with that specific energy as the new elements #99 and #100 respectively.

For security reasons, these observations in late 1952 and early 1953 could not be published in the open literature. The first publication concerning element 99, in 1954, reported the production of a 7.3 minute isotope. Shortly afterwards, also in 1954, the detection of elements 99 and 100 in plutonium samples which had been exposed to an intense neutron flux was reported.

The full story of the discovery of elements 99 and 100 was finally published in mid-1955 by a group of authors of the laboratories involved. Element #99 was named Einsteinium.

Albert Einstein (Ulm 1879-Princeton, N.J., 1955). German-Swiss physicist, who formulated the theory of relativity (1905), and did important work in radiation physics and thermodynamics. Nobel prize for physics 1921. He emigrated to the USA in 1933 and became professor of mathematics at Princeton, New Jersey.
Here a comprehensive biography. by the School of Mathematics and Statistics, University of St Andrews, Scotland.

Athenium

In non-specialist magazines of the year 1950/51 the first reports were published on the discovery of elements 99 and 100. Element 99 got the name Athenium (An), after the Greek capital Athens, were 2500 years ago for the first time the philosophical idea of atoms as building stones of matter was developed. Element 100 was named Centurium (see Fermium) (note).

Further reading:

• Mary Elvira Weeks, Discovery of the Elements, comp. rev. by Heny M. Leicester (Easton, Pa.: Journal of Chemical Education, 1968), pp. 850-851.
• Earl K. Hyde & Glenn T. Seaborg, Transurane : Teil A 1, I: Die Elemente. Gmelins Handbuch der anorganische Chemie, Ergänzungswerk zur 8. Aufl.; Band 7a. Weinheim/Bergstrasse: Chemie, 1973.
• Glenn T. Seaborg, Early History of LBNL, A transcript of the lecture on the 65th Anniversary of Lawrence Berkeley National Laboratory, August 26, 1996 (on-line).
• A. Ghiorso, S.G. Thompson, G.H. Higgins, G.T. Seaborg, M.H. Studier, P.R. Fields, H. Diamond, J.F. Mech, G.L. Pyle, J.R. Huizenga, A. Hirsch, W.M. Manning, C.I. Browne, H.L. Smith, and R.W. Spence, "New Elements Einsteinium and Fermium, Atomic Numbers 99 and 100". Phys. Rev. 99 (1955), 1048.