| General | |
|---|---|
| Symbol | 192Ir |
| Names | Iridium-192, 192Ir, Ir-192 |
| Protons(Z) | 77 |
| Neutrons(N) | 115 |
| Nuclide data | |
| Natural abundance | synthetic |
| Half-life(t1/2) | 73.827 days |
| Isotope mass | 191.9626050(18)Da |
| Spin | 4+ |
| Parent isotopes | 192mOs (β−) |
| Decay products | 192Pt 192Os |
| Decay modes | |
| Decay mode | Decay energy (MeV) |
| Isotopes of iridium Complete table of nuclides | |
Iridium-192 (symbol192Ir) is a radioactiveisotope of iridium, with ahalf-life of 73.827 days.[1] It decays by emitting beta (β) particles and gamma (γ) radiation. About 96% of192Ir decays occur via emission of β and γ radiation, leading to192Pt. Some of the β particles are captured by other192Ir nuclei, which are then converted to192Os. Electron capture is responsible for the remaining 4% of192Ir decays.[2] Iridium-192 is normally produced by neutron activation of natural-abundance iridium metal.[3] Iridium-192 is a very stronggamma ray emitter, with a gamma dose-constant of approximately 1.54μSv·h−1·MBq−1 at 30 cm, and a specific activity of 341TBq·g−1 (9.22kCi·g−1).[4][5] There are seven principal energy packets produced during its disintegration process ranging from just over 0.2 to about 0.6 MeV. It is commonly used as a gamma ray source inindustrial radiography to locate flaws in metal components.[6] It is also used inradiotherapy as a radiation source, in particular inbrachytherapy. Iridium-192 has accounted for the majority of cases tracked by the U.S.Nuclear Regulatory Commission in which radioactive materials have gone missing in quantities large enough to make adirty bomb.[7]
Themetastable isomer192m2Ir is iridium's most stable isomer. It decays byisomeric transition with a half-life of 241 years,[8] which makes it unusual, both for its long half-life for an isomer, and that said half-life greatly exceeds that of the ground state of the same isotope.