Betastraling

Betastraling is a term used in several languages to denote beta radiation, the emission of beta particles from unstable atomic nuclei. Beta particles are high-energy electrons (beta minus) or positrons (beta plus) released during radioactive decay, typically accompanied by a neutrino.

In beta minus decay, a neutron inside the nucleus converts to a proton, emitting an electron and an electron antineutrino, and increasing the atomic number by one. In beta plus decay, a proton converts to a neutron, emitting a positron and an electron neutrino, and decreasing the atomic number by one. The energy spectrum of beta particles is continuous because the decay involves three bodies (the beta particle, the neutrino, and the daughter nucleus). Beta decay competes with other decay modes and occurs across a wide range of half-lives, from fractions of a second to millions of years.

Shielding and exposure: beta radiation can be effectively shielded by relatively thin materials. Low-energy betas are stopped by a few millimeters of plastic or glass, while higher-energy betas may require several millimeters of aluminum or similar material. External exposure risk is most significant to the skin or eyes; internal exposure from ingestion or inhalation of beta-emitting substances poses greater health risks.

Detection and measurement: activity is measured in becquerels (decays per second). Dosimetry uses gray and sievert to express absorbed dose and effective dose. Common detectors include Geiger–Maunders counters, scintillation detectors, and spectrometric instruments.

Applications and safety: beta emitters are used as radiotracers in medicine and industry, and in therapy and research. Positron-emitting isotopes are central to positron emission tomography (PET). Safety relies on shielding, containment, proper handling, and adherence to regulatory limits to minimize external and internal exposure. History of beta decay dates to early 20th-century discoveries, with theoretical descriptions developed by Fermi and subsequent physicists.