Which type of radiation is commonly used in smoke detectors?

The type of radiation commonly used in smoke detectors is alpha particles. Smoke detectors that utilize this type of radiation typically contain a small amount of americium-241, which emits alpha particles as it decays. In a smoke detector, a small electrical current is maintained between two electrodes, and the alpha particles ionize the air between them. When smoke enters the detector, it disrupts this ionization process, reducing the current and triggering the alarm.

This mechanism is effective for detecting smoke because the alpha radiation is contained within the detector and does not penetrate through materials, making it safe for home use. Options that include beta particles, gamma rays, or neutron radiation are less suitable for such applications due to their different properties and behaviors. Beta particles, for instance, have greater penetration power, which makes them unsuitable for the environment of a smoke detector. Gamma rays could also penetrate the materials of a smoke detector and would not be as sensitive to smoke particles as alpha radiation. Neutron radiation is not used in smoke detectors primarily due to the complexity and safety implications of its use in residential applications.