Americium

Americium was the fourth transuranium element to be discovered. ²⁴¹Am was identified by G.T. Seaborg, R.A. James, L.O. Morgan and A. Ghiorso in late 1944 in Metallurgical Laboratory of the University of Chicago, USA as the result of successive neutron capture reactions by plutonium isotopes in a nuclear reactor [3].

From the English "The Americas" [3]