Pb211

Pb-211, or lead-211, is a radioactive isotope of lead with a mass number of 211. It has 82 protons and 129 neutrons and is one of the heavier, short-lived isotopes of lead. Pb-211 is produced in nuclear reactions in reactors or particle accelerators, typically by irradiating lead targets with neutrons or by spallation processes, and can also appear as a product in certain decay chains following irradiation of heavier elements.

The nucleus of Pb-211 is unstable and undergoes beta-minus decay to form Bi-211, with a half-life on the order of tens of minutes. The Bi-211 nuclide that results from this decay is itself radioactive and participates in further decay processes, contributing to the radiation emitted in the decay chain.

Pb-211 is of interest largely as a potential generator for Bi-211, an alpha-emitting isotope used in radiopharmaceutical research and discussions of targeted alpha therapy. The relatively short half-life of Pb-211 makes on-site production and careful radiological handling essential, and its use is typically confined to facilities equipped to manage short-lived radionuclides and to carry out related radiochemistry.

In isotopic terms, Pb-211 represents a transient member of the lead family, lying in the heavy-mass region near the lead–bismuth transition. Its primary practical significance arises from its role in generating Bi-211 for research and potential therapeutic applications, rather than from any long-term natural abundance or stability.

See also: Lead isotopes, Bi-211, Targeted alpha therapy, Radioisotope generators.