Half-life: 2.6 years
Main emission lines: 40, 121 keV
Decay chain: Sm-147
Promethium-147 (Pm-147) is a radioactive isotope of promethium with a half-life of approximately 2.62 years. It undergoes beta decay, emitting low-energy beta particles without significant gamma radiation, which makes it suitable for certain industrial and scientific applications. Pm-147 does not occur naturally in significant amounts; it is typically produced artificially in nuclear reactors as a fission product of uranium or through neutron activation of neodymium-146.
Pm-147 is widely used in industry and technology. Its low-energy beta emissions make it an excellent source for thin-film thickness measurement and quality control in manufacturing processes. It is also used in the production of phosphorescent materials for luminescent dials, signs, and gauges. Some signal lights use a luminous paint containing a phosphor that absorbs the beta radiation emitted by promethium-147 and emits light.
This isotope does not cause aging of the phosphor, as alpha emitters do, and therefore the light emission is stable for a few years. Originally, radium-226 was used for the purpose, but it was later replaced by promethium-147 and tritium (hydrogen-3).
Additionally, Pm-147 serves as a power source in radioisotope thermoelectric generators (RTGs) for space applications and other remote power needs, as its beta radiation can be efficiently converted to electricity.
Pm-147 is not naturally occurring in measurable quantities due to its relatively short half-life. It is produced as a byproduct in nuclear reactors, particularly during the fission of uranium-235 or plutonium-239. Pm-147 is found in controlled environments, such as research laboratories, industrial settings, and facilities involved in the production of radiopharmaceuticals or specialized instruments. Its production and use are carefully regulated due to its radioactive nature.. Promethium-147 is also used, albeit in very small quantities (less than 330nCi), in some Philips CFL (Compact Fluorescent Lamp) glow switches in the PLC 22W/28W 15mm CFL range.
Promethium-147 is also used, albeit in very small quantities (less than 330nCi), in some Philips CFL (Compact Fluorescent Lamp) glow switches in the PLC 22W/28W 15mm CFL range.