but are not yet officially named, use IUPAC's systematic element names. The naming of transuranic elements may be a source of controversy. Discovery and naming of transuranium elements So far, essentially all the transuranium elements have been discovered at four laboratories: Lawrence Berkeley National Laboratory in the United States (elements 93–101, 106, and joint credit for 103–105), the Joint Institute for Nuclear Research in Russia (elements 102 and 114–118, and joint credit for 103–105), the GSI Helmholtz Centre for Heavy Ion Research in Germany (elements 107–112), and RIKEN in Japan (element 113). The Radiation Laboratory (now Lawrence Berkeley National Laboratory) at the University of California, Berkeley, led principally by Edwin McMillan, Glenn Seaborg, and Albert Ghiorso, during 1945-1974: 93. neptunium, Np, named after the planet Neptune, as it follows uranium and Neptune follows Uranus in the planetary sequence (1940). 94. plutonium, Pu, named after the then-planet Pluto, following the same naming rule as it follows neptunium and Pluto follows Neptune in the Solar System (1940). 95. americium, Am, named because it is an analog to europium, and so was named after the continent where it was first produced (1944). 96. curium, Cm, named after Pierre and Marie Curie, famous scientists who separated out the first radioactive elements (1944), as its lighter analog gadolinium was named after Johan Gadolin. 97. berkelium, Bk, named after the city of Berkeley, where the University of California, Berkeley is located (1949). 98. californium, Cf, named after the state of California, where the university is located (1950). 99. einsteinium, Es, named after the theoretical physicist Albert Einstein (1952). 100. fermium, Fm, named after Enrico Fermi, the physicist who produced the first controlled chain reaction (1952). 101. mendelevium, Md, named after the Russian chemist Dmitri Mendeleev, credited for being the primary creator of the periodic table of the chemical elements (1955). 102. nobelium, No, named after Alfred Nobel (1958). This discovery was also claimed by the JINR, which named it joliotium (Jl) after Frédéric Joliot-Curie. IUPAC concluded that the JINR had been the first to convincingly synthesise the element, but retained the name nobelium as deeply entrenched in the literature. 103. lawrencium, Lr, named after Ernest O. Lawrence, a physicist best known for development of the cyclotron, and the person for whom the Lawrence Livermore National Laboratory and the Lawrence Berkeley National Laboratory (which hosted the creation of these transuranium elements) are named (1961). This discovery was