betaemitters

Beta emitters are radionuclides that decay by beta emission. There are two main types: beta-minus, in which a neutron is transformed into a proton with emission of an electron and an antineutrino; and beta-plus, in which a proton is transformed into a neutron with emission of a positron and a neutrino. In beta-plus decay, the emitted positron soon encounters an electron, leading to annihilation and emission of two 511 keV gamma photons, which contributes to the gamma radiation from some beta emitters.

Beta particles have varying kinetic energies up to a maximum endpoint energy. Their penetration in matter is moderate: they can travel a few millimeters to meters of air depending on energy; shielding usually requires plastic, glass, acrylic, or thin metal; high-energy beta emitters may require denser shielding and additional containment to prevent bremsstrahlung production.

Common beta-emitting radionuclides include tritium (3H), carbon-14, phosphorus-32, strontium-90, yttrium-90, iodine-131, and lutetium-177. The choice depends on half-life, beta energy, and biological behavior. Applications include radiometric dating (carbon-14), tracing and labeling in biological systems, and medical therapies (e.g., thyroid treatment with iodine-131, targeted therapies with yttrium-90 or lutetium-177).

Safety and regulation emphasize controlling internal contamination, minimizing external exposure, and proper shielding and handling. Detection and measurement rely on devices such as Geiger counters, scintillation detectors, and beta spectrometers, often supported by imaging techniques for positron emitters (PET) where applicable.