lan, Kennedy, and Wahl; it had an [alpha]-decay
half-life of 86.4 years, which gave it sufficient radioactivity so that
its chemistry could be studied.

Having found these chemical properties in Pu<238>, experimenters knew
{94}Pu<239> would behave similarly. It was soon shown that the nucleus of
{94}Pu<239> would undergo fission in the same way as {92}U<235> when
bombarded with slow neutrons and that it could be produced in the newly
assembled atomic pile. Researchers wished to learn as much as possible
about its chemistry; therefore, during the summer of 1942 two large
cyclotrons at St. Louis and Berkeley bombarded hundreds of pounds of
uranium almost continuously. This resulted in the formation of 200
micrograms of plutonium. From this small amount, enough of the chemical
properties of the element were learned to permit correct design of the
huge plutonium-recovery plant at Hanford, Washington. In the course of
these investigations, balances that would weigh up to 10.5 mg with a
sensitivity of 0.02 microgram were developed. The "test tubes" and
"beakers" used had internal diameters of 0.1 to 1 mm and could measure
volumes of 1/10 to 1/10,000 ml with an accuracy of 1%. The fact that
there was no intermediate stage of experimentation, but a direct
scale-up at Hanford of ten billion times, required truly heroic skill
and courage.

By 1944 sufficient plutonium was available from uranium piles (reactors)
so that it was available as target material for cyclotrons. At Berkeley
it was bombarded with 32-MeV doubly charged helium ions, and the
following reactions took place:

{94}Pu<239> ([alpha], n) {96}Cm<242> [alpha] / 150 days --> {94}Pu<238>.

This is to be read: plutonium having an atomic number of 94 (94
positively charged protons in the nucleus) and a mass number of 239 (the
whole atom weighs approximately 239 times as much as a proton), when
bombarded with alpha particles (positively charged helium nuclei) reacts
to give off a neutron and a new element, curium, that has atomic number
96 and mass number 242. This gives off alpha particles at such a rate
that half of it has decomposed in 150 days, leaving plutonium with
atomic number 94 and mass number 238. The radiochemical work leading to
the isolation and identification of the atoms of element 96 was done at
the metallurgical laboratory of the University of Chicago.

The intense neutron flux available in modern reactors led to a new
element, americium (Am), a