(Pu) 239 Pu<239>; the fissionable isotope of plutonium, was also discovered in 1941 by J. W. Kennedy, G. T. Seaborg, E. Segrè and A. C. Wahl; University of California at Berkeley; slow-neutron bombardment of U<238> in the 60-inch cyclotron. ------------------------------------------------------------------------ 95 Americium (Am) 241 1944-45; Berkeley scientists A. Ghiorso, R. A. James, L. O. Morgan, and G. T. Seaborg at the University of Chicago; intense neutron bombardment of plutonium in nuclear reactors. ------------------------------------------------------------------------ 96 Curium (Cm) 242 1945; Berkeley scientists A. Ghiorso, R. A. James, and G. T. Seaborg at the University of Chicago; bombardment of Pu<239> by 32-MeV helium ions from the 60-inch cyclotron. ------------------------------------------------------------------------ 97 Berkelium (Bk) 243 1949; S. G. Thompson, A. Ghiorso, and G. T. Seaborg; University of California at Berkeley; 35-MeV helium-ion bombardment of Am<241>. ------------------------------------------------------------------------ 98 Californium (Cf) 245 1950; S. G. Thompson, K. Street, A. Ghiorso, G. T. Seaborg; University of California at Berkeley; 35-MeV helium-ion bombardment of Cm<242>. ------------------------------------------------------------------------ 99 Einsteinium (Es) 253 1952-53; A. Ghiorso, S. G. 100 Fermium (Fm) 255 Thompson, G. H. Higgins, G. T. Seaborg, M. H. Studier, P. R. Fields, S. M. Fried, H. Diamond, J. F. Mech, G. L. Pyle, J. R. Huizenga, A. Hirsch, W. M. Manning, C. I. Browne, H. L. Smith, R. W. Spence; "Mike" explosion in South Pacific; work done at University of California at Berkeley, Los Alamos Scientific Laboratory, and Argonne National Laboratory; both elements created by multiple capture of neutrons in uranium of first detonation of a thermonuclear device. The elements were chemically isolated from the debris of the explosion. ------------------------------------------------------------------------ 101 Mendelevium (Md) 256 1955; A. Ghiorso, B. G. Harvey, G. R. Choppin, S. G. Thompson, G. T. Seaborg; University of California at Berkeley; 41-MeV helium-ion bombardment of Es<253> in 60-inch cyclotron. ------------------------------------------------------------------------ 102 Unnamed[B] 254 1958; A. Ghiorso, T. Sikkeland, A. E. Larsh, R. M. Latimer; University of California, Lawrence Radiation Laboratory, Berkeley; 68-MeV carbon-ion bombardment of Cm<246> in heavy-ion linear accelerator (Hilac). ------------------------------------------------------------------------ 103 Lawrencium 257 1961; A. Ghiorso, T. Sikkeland, A. E. Larsh, R. M. Latimer; University of California, Lawrence Radiation Laboratory, Berkeley; 70-MeV boron-ion bombardment of Cf<250>, Cf<251>, and Cf<252> in Hilac. ========================================================================