Short answers, pulled from the story.
Glenn T. Seaborg, Leon O. Morgan, Ralph A. James, and Albert Ghiorso created americium in late autumn 1944 at the University of California, Berkeley. The results remained classified until November 1945 when they were finally released to the public.
Scientists produced americium by evaporating plutonium-239 nitrate onto platinum foil before irradiating it with a 60-inch cyclotron. They dissolved the coating using concentrated nitric acid and precipitated the material as hydroxide using aqueous ammonia for further separation via ion exchange techniques.
Freshly prepared americium displays a silvery-white metallic lustre that slowly tarnishes upon exposure to air. Its density measures 12 grams per cubic centimeter and its melting point reaches 1173 degrees Celsius.
Household smoke detectors utilize americium-241 as their primary source of ionizing radiation because alpha particles pass through an air-filled ionization chamber between two electrodes creating a constant current. Any smoke entering the chamber absorbs these alpha particles reducing ionization levels which triggers the alarm system immediately.
The isomer 242mAm possesses a half-life of 141 years and exhibits massive neutron absorption cross sections suitable for spacecraft propulsion systems or hospital radiation therapy treatments. A single 3.2 kilogram charge of 242mAm could provide roughly 140 kilowatts over eighty days according to researchers at the UK National Nuclear Laboratory who demonstrated heat generation capabilities in 2019.