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Gammas are waaaay too penetrating and would leave the detector. Even multi-MeV alphas will not penetrate the layer of dead skin cells you have.May 14, 2019

Why would a smoke detector not work with gamma rays?

(c) The smoke alarm would not work with a radiation source that emits beta or gamma radiation. Explain why. Most of the beta and gamma radiation would penetrate smoke and no change in the count rate would be detected.

Do smoke detectors use gamma rays?

Americium-241, with a half-life of 432 years, was the first americium isotope to be isolated, and is the one used today in most domestic smoke detectors. Am-241 decays by emitting alpha particles and gamma radiation to become neptunium-237.

Why does a smoke detector use alpha radiation rather than beta or gamma?

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.

Which type of radiation is used in smoke detectors?

alpha particles 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.

Are gamma rays radioactive?

The penetrating power of gamma rays has many applications. However, while gamma rays penetrate many materials, this does not make them radioactive. The three radionuclides that are by far the most useful are cobalt-60, caesium-137, technetium-99m and americium-241.

Why is americium 242 not used in smoke detectors?

(i) The smoke detector would not work if a radioactive source that emitted only gamma rays was used. (ii) Curium-242 is a radioactive isotope with a half-life of 160 days. It emits alpha particles.

What is gamma radiation used for?

Gamma rays are ionizing electromagnetic radiation, obtained by the decay of an atomic nucleus. Gamma rays are more penetrating, in matter, and can damage living cells to a great extent. Gamma rays are used in medicine (radiotherapy), industry (sterilization and disinfection) and the nuclear industry.

Why are beta particles not used in smoke detectors?

Some early models used radium-226, and commercial smoke detectors and some residential units used nickel-63. The types of radiation from these sources cannot make anything else radioactive. Ni-63 emits beta particles, which can travel a few feet but cannot penetrate a smoke detectors plastic housing.

Are smoke detectors radioactive?

Ionization chamber smoke detectors contain a small amount of americium-241, a radioactive material. Smoke particles disrupt the low, steady electrical current produced by radioactive particles and trigger the detector's alarm. They react quickly to fires that give off little smoke.