betastråler

Betastråler are a form of ionizing radiation consisting of high-energy electrons or positrons emitted by unstable atomic nuclei during beta decay. There are two main types: beta minus (β−) radiation, where a neutron in the nucleus converts to a proton, releasing an electron (the beta particle) and an antineutrino; and beta plus (β+) radiation, where a proton converts to a neutron, emitting a positron and a neutrino. The emitted particles carry a spectrum of energies, typically from tens of keV up to a few MeV, which is continuous rather than a single energy.

Beta radiation interacts with matter primarily through ionization and excitation of atoms. Beta minus and beta plus particles have different penetration capabilities: they are more penetrating than alpha particles but can be stopped by relatively modest shielding. Common shielding materials include plastics, glass, and thin metals such as aluminum. In high-Z materials, beta-plus radiation can produce secondary bremsstrahlung gamma rays, which may require additional shielding to limit exposure. The penetration depth in tissue is limited, ranging from a few millimeters to a few centimeters depending on energy, making external exposure different from internal exposure.

Detection and measurement of betastråler use standard radiation detectors such as Geiger–Müller counters, scintillation detectors, and semiconductor devices. In medicine, beta-emitting isotopes are used in targeted radiotherapy (for example yttrium-90, strontium-90, and lutetium-177) and in some diagnostic applications. Safety considerations focus on controlling exposure, proper containment of radioactive sources, and appropriate shielding based on the specific energy and activity involved.