How Is Alpha Used In Smoke Alarms?

An isotope of americium which emits alpha particles is used in smoke alarms. Alpha radiation ionises the air and this allows a small current to flow between two electrodes. Alpha is weakly penetrating so smoke stops it, the current drops and the alarm goes off.


Are ionization smoke detectors banned? Currently, ionization-type smoke detectors are banned in three states: Massachusetts, Iowa, and Vermont. However, elsewhere they are the dominant type of smoke detector, due to their low price.

how is radioactivity used in smoke detectors?

Ionization chamber smoke detectors rely on radiation to "ionize" the air inside the chamber. A radioactive source "decays," or sheds particles and photons from unstable atoms. The particles interact with neutral air molecules flowing through the chamber.

Is americium 241 dangerous? Hazards. Americium-241 has the same general hazards as other americium isotopes: it is both extremely toxic and radioactive. Although α-particles can be stopped by a sheet of paper, there are serious health concerns for ingestion of α-emitters.

how is americium 241 used in smoke detectors?

Ionisation detectors contain a very small amount of radioactive material called Americium-241 which is bound in a metal foil. Americium-241 emits alpha particles and low energy gamma rays. The alpha particles are absorbed within the detector, while most of the gamma rays escape harmlessly.

Why is alpha radiation best for smoke detectors? An isotope of americium which emits alpha particles is used in smoke alarms. Alpha radiation ionises the air and this allows a small current to flow between two electrodes. Alpha is weakly penetrating so smoke stops it, the current drops and the alarm goes off.

what radioactive material is used in smoke detectors?

americium-241

Which type of smoke detector is best? Best smoke detector overall: First Alert Smoke and Carbon Monoxide Alarm. Best hardwired smoke detector: Kidde Smoke Alarm Dual Sensor. Best dual-sensor smoke detector: First Alert Photoelectric and Ionization Smoke Alarm. Best affordable smoke detector: Kidde Hardwire Smoke Alarm.

Why is gamma radiation not used in smoke detectors?

A Smoke detector uses either a photoelectric cell or an ionization to detect smoke. An alpha particle can't even escape form the detector. A gamma ray, on the other hand, produces few ions and goes much further. If you use a gamma emitter, it produces far fewer ions and travels much

How do you get rid of old smoke detectors? When it comes to disposal, old photoelectric detectors can be safely put in the trash, so long as you remove the battery first. Read on for information about ionization detectors. Ionization-Based Smoke Detectors: Ionization detectors contain a small amount of Americium 241, a radioactive isotope.

How many Microcuries are dangerous?

1 curie = 3.70 x 10^10 disintegrations per sec. In today's units 1 curie is about 30 Giga Becquerel. So a curie of any radioactivity (alpha, beta or gamma) would fry you. A sealed microcurie source could be safely handled.

What radiation does americium 241 give off?

Americium and Health Am-241 is primarily an alpha emitter, but also emits some gamma rays.

Why is it safe to use a source of alpha radiation in a house?

alpha radiation is not as dangerous because it is unlikely to reach living cells inside the body. beta and gamma radiation are the most dangerous sources because they can penetrate the skin and damage the cells inside.

Do smoke detectors still used 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.

Why are americium smoke detectors safe?

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.

Are all isotopes radioactive?

Radioactive isotopes are often called radioisotopes. All elements with atomic numbers greater than 83 are radioisotopes meaning that these elements have unstable nuclei and are radioactive.

Why is protection from radiation necessary?

Scientists know exactly how much shielding is necessary in order to protect the body from radiation. In order to reduce typical gamma rays by a significant factor, thick, dense shielding is necessary. The problem is that the required shielding makes full-body protection outfits very heavy and difficult to maneuver in.

How is americium 241 produced?

The isotope americium-241 was made by bombarding uranium-238 with alpha particles (helium nuclei). This produced plutonium-241 which decays to the Am-241. This isotope decays slowly by alpha emission with a halflife of 500 years. It has been used as a source in smoke detectors.

Why do smoke detectors expire?

Smoke Alarms Eventually Expire This is because the sensors eventually degrade in quality to the point where they're no longer effective.

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