What is the half-life of a smoke detector?

432.2 years
The isotope of americium used in smoke detectors is americium-241, which decays by α emission to neptunium-237 with a half-life of 432.2 years.

How long does it take for americium to decay?

The time in which half the atoms of a radioactive substance disintegrate to another nuclear form is known as the half-life. The half-life of americium-241 is about 432 years.

Why is it important that americium-241 has a long half-life?

Like all isotopes of americium, it is radioactive, with a half-life of 432.2 years. Am is the most common isotope of americium as well as the most prevalent isotope of americium in nuclear waste….Americium-241.

How is americium used in smoke detectors?

Ionization smoke detectors use americium as a source of alpha particles. Alpha particles from the americium source ionize air molecules. This makes some particles positively charged and some negatively charged. The smoke alarm triggers when smoke breaks the constant flow of ions.

How are isotopes used in smoke alarms?

The Am-241 emits alpha particles which ionise the air and allow a current between two electrodes. If smoke enters the detector it absorbs the alpha particles and interrupts the current, setting off the alarm.

What is the half-life of americium-242?

16.02 hrs
DECAY PATHWAY: Americium-242, half-life 16.02 hrs, 17.3\% decays via electron capture, 0.751 MeV, to plutonium-242, half-life 373,300 years.

Why is americium-241 used in smoke detectors?

Ionization smoke detectors use americium as a source of alpha particles. Alpha particles from the americium source ionize air molecules. This makes some particles positively charged and some negatively charged. Because of this shielding, the smoke detector poses no radiation health risk when they are properly handled.

Is americium still used in smoke detectors?

Smoke detectors are common household items that keep you and your family safe by alerting you to smoke in your home. Ionization smoke detectors use a small amount of radioactive material, americium-241, to detect smoke.

How are isotopes used in smoke detectors?

What is americium used for?

Americium is a silvery, shiny radioactive metal. Americium is commonly used in smoke alarms, but has few other uses. It has the potential to be used in spacecraft batteries in the future. Currently plutonium is used but availability is poor so alternatives are being considered.

What is the half life of americium used in smoke detectors?

Americium The isotope of americium used in smoke detectors is americium-241, which decays by α emission to neptunium-237 with a half-life of 432.2 years. [3] ( The isotope americium-243 also decays by α emission and is longer-lived at 7370 years, but it is obtained by irradiating americium-241 with neutrons so it is more expensive.)

How much americium is in a modern radio detector?

As can be seen from Fig. 1, a typical modern detector contains about 1.0 microcurie of the radioactive element americium, which is equivalent to 37 kilobecquerel (37,000 decays per second), or 0.33 micrograms of americium oxide (AmO2). The average quantity of americium per detector has decreased from 3 microcurie in 1978. [2]

What is the longest lasting isotope in the universe?

The two longest-lived isotopes in this decay chain are uranium-233 (159,200 years) and bismuth-209 (1.9×1019years). For all practical purposes, the radiation source in the typical smoke detector contains mostly americium and neptunium, with very small quantities of other elements. When the smoke detector is new, it is close to 100\% americium.

Are ionization smoke detectors safe to use?

While they are safe to use in your home, never tamper with an ionization smoke detector. Replace the batteries in your smoke detectors every year. Smoke detectors are common household items that keep you and your family safe by alerting you to smoke in your home.