Lähisäteily

Lähisäteily, meaning "near radiation" in Finnish, refers to a phenomenon where electromagnetic radiation or energetic particles are emitted from a source and travel relatively short distances before interacting with matter or dissipating. This term is often used in contexts related to radiation safety, nuclear physics, and particle physics to distinguish it from far-field radiation or radiation that travels long distances.

In practical applications, understanding lähisäteily is crucial for designing shielding and protective measures. For instance, in a nuclear reactor, the radiation emitted from the core is considered lähisäteily for workers in its immediate vicinity. Similarly, in medical imaging or radiation therapy, the radiation delivered to a target area is a form of lähisäteily. The intensity of lähisäteily typically decreases rapidly with distance from the source, following an inverse square law for point sources of electromagnetic radiation.

The specific type of radiation encompassed by lähisäteily can vary. It can include alpha particles, beta particles, gamma rays, neutrons, or even specific wavelengths of electromagnetic radiation like X-rays or UV light, depending on the context. The interaction of lähisäteily with biological tissues or materials is a key concern in fields like health physics, where efforts are made to minimize exposure to ensure safety. The term emphasizes the localized nature of the radiation's impact.