It is commonly found in ionization type smoke detectors and is a potential fuel for long-lifetime radioisotope thermoelectric generators (RTGs).

This isotope also has one meta state, 241mAm, with an excitation energy of 2.2 MeV (0.35 pJ) and a half-life of 1.23 μs.

Because of the low penetration of alpha radiation, americium-241 only poses a health risk when ingested or inhaled.

Americium-241 has been produced in small quantities in nuclear reactors for decades, and many kilograms of 241Am have been accumulated by now.

[4]: 1262  Nevertheless, since it was first offered for sale in 1962, its price, about US$1,500 per gram of 241Am, remains almost unchanged owing to the very complex separation procedure.

[6] The obtained 241Am can be used for generating heavier americium isotopes by further neutron capture inside a nuclear reactor.

[9] The second most common type of decay that americium-241 undergoes is spontaneous fission, with a branching ratio of 3.6×10−12[10] and happening 1.2 times a second per gram of 241Am.

Americium-241 is the only synthetic isotope to have found its way into the household, where the most common type of smoke detector (the ionization-type) uses 241AmO2 (americium-241 dioxide) as its source of ionizing radiation.

[11] This isotope is preferred over 226Ra because it emits 5 times more alpha particles and relatively little harmful gamma radiation.

Some old industrial smoke detectors (notably from the Pyrotronics Corporation) can contain up to 80 microcuries (3,000 kBq).

The amount of 241Am declines slowly as it decays into neptunium-237 (237Np), a different transuranic element with a much longer half-life (about 2.14 million years).

The radiated alpha particles pass through an ionization chamber, an air-filled space between two electrodes, which allows a small, constant electric current to pass between the capacitor plates due to the radiation ionizing the air space between.

Any smoke that enters the chamber blocks/absorbs some of the alpha particles from freely passing through and reduces the ionization and therefore causes a drop in the current.

The alarm's circuitry detects this drop in the current and as a result, triggers the piezoelectric buzzer to sound.

The briquette is then processed through several stages of cold rolling to achieve the desired thickness and levels of radiation emission.

Each disc, about 0.2 inches (5.1 mm) in diameter, is mounted in a metal holder, usually made of aluminium.

The thin rim on the holder is rolled over to completely seal the cut edge around the disc.

[17] Even though americium-241 produces less heat and electricity than plutonium-238 (the power yield is 114.7 milliwatts per gram [3.25 watts per ounce] for 241Am vs. 570 mW/g [16 W/oz] for 238Pu)[17] and its radiation poses a greater threat to humans owing to gamma and neutron emission, it has advantages for long duration missions with its significantly longer half-life.

[22] Americium-241 is sometimes used as a starting material for the production of other transuranic elements and transactinides – for example, neutron bombardment of 241Am yields 242Am:

In the nuclear reactor, 242Am is also up-converted by neutron capture to 243Am and 244Am, which transforms by β-decay to 244Cm: Irradiation of 241Am by 12C or 22Ne ions yields einsteinium-253 (253Es) or dubnium-263 (263Db), respectively.

[23] Furthermore, the element berkelium (243Bk isotope) had been first intentionally produced and identified by bombarding 241Am with alpha particles, in 1949, by the same Berkeley group, using the same 60-inch (1,500 mm) cyclotron that had been used for many previous experiments.

[4]: 1262 Americium-241 has been used as a portable source of both gamma rays and alpha particles for a number of medical and industrial uses.

The 59.5409 keV (9.53950 fJ) gamma ray emissions from 241Am in such sources can be used for indirect analysis of materials in radiography and X-ray fluorescence spectroscopy, as well as for quality control in fixed nuclear density gauges and nuclear densometers.

[4]: 1262  Americium-241 is also suitable for calibration of gamma-ray spectrometers in the low-energy range, since its spectrum consists of nearly a single peak and negligible Compton continuum (at least three orders of magnitude lower intensity).

241Am radiographs have only been taken experimentally due to the long exposure time which increases the effective dose to living tissue.

Though α-particles can be stopped by a sheet of paper, there are serious health concerns for ingestion of α-emitters.

Safely handling americium-241 requires knowing and following proper safety precautions, as without them it would be extremely dangerous.

In the U.S., the "Radioactive Boy Scout" David Hahn was able to concentrate americium-241 from smoke detectors after managing to buy a hundred of them at remainder prices and also stealing a few.

[29][30][31][32] There have been a few cases of exposure to americium-241, the worst being Harold McCluskey who, at age 64, was exposed to 500 times the occupational standard for americium-241 as a result of an explosion in his lab.

McCluskey died at age 75, not as a result of exposure, but of a heart disease which he had before the accident.