Iridium-192
| General | |
|---|---|
| Symbol | 192Ir |
| Names | Iridium-192 |
| Protons (Z) | 77 |
| Neutrons (N) | 115 |
| Nuclide data | |
| Natural abundance | synthetic |
| Half-life (t1/2) | 73.82 days[1] |
| Isotope mass | 191.962605[2] 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 (symbol 192Ir) is a radioactive isotope of iridium, with a half-life of 73.82 days. It decays by emitting beta (β) particles and gamma (γ) radiation. 95.24% of 192Ir decays occur via β- emission, leading to 192Pt; the remaining 4.76% occur via electron capture to 192Os; both modes involve gamma emission. Iridium-192 is normally produced by neutron activation of natural-abundance iridium metal.[3] Iridium-192 is a very strong gamma ray emitter, with a gamma dose constant of 1.54 μSv·h−1·MBq−1 at 30 cm, and a specific activity of 341 TBq·g−1 (9.22 kCi·g−1).[4][5] There are seven principal gamma rays produced in its beta-minus decay, ranging from 296.0 to 612.5 keV, and two produced in its electron capture decay at 205.8 and 484.6 keV.[6] It is commonly used as a gamma ray source in industrial radiography to locate flaws in metal components.[7] It is also used in radiotherapy as a radiation source, in particular in brachytherapy. 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 a dirty bomb.[8]
The metastable isomer 192m2Ir is iridium's most stable isomer. It decays solely by isomeric transition (to this ground state) with a half-life of 241 years,[1] which is somewhat unusual for its long half-life and that said half-life greatly exceeds that of the ground state.
See also
References
- ^ a b Kondev, F. G.; Wang, M.; Huang, W. J.; Naimi, S.; Audi, G. (2021). "The NUBASE2020 evaluation of nuclear properties" (PDF). Chinese Physics C. 45 (3): 030001. doi:10.1088/1674-1137/abddae.
- ^ Wang, Meng; Huang, W.J.; Kondev, F.G.; Audi, G.; Naimi, S. (2021). "The AME 2020 atomic mass evaluation (II). Tables, graphs and references*". Chinese Physics C. 45 (3): 030003. doi:10.1088/1674-1137/abddaf.
- ^ "Isotope Supplier: Stable Isotopes and Radioisotopes from ISOFLEX - Iridium-192". www.isoflex.com. Retrieved 2017-10-11.
- ^ Delacroix, D; Guerre, J P; Leblanc, P; Hickman, C (2002). "Radionuclide and Radiation Protection Data Handbook" (PDF). Radiation Protection Dosimetry. 98 (1) (2nd ed.). Ashford, Kent: Nuclear Technology Publishing: 9–168. doi:10.1093/OXFORDJOURNALS.RPD.A006705. ISBN 1870965876. PMID 11916063. S2CID 123447679. Archived from the original (PDF) on 2019-08-22.
- ^ Unger, L M; Trubey, D K (May 1982). Specific Gamma-Ray Dose Constants for Nuclides Important to Dosimetry and Radiological Assessment (PDF) (Report). Oak Ridge National Laboratory. Archived from the original (PDF) on 22 March 2018.
- ^ National Nuclear Data Center. "NuDat 3.0 database". Brookhaven National Laboratory.
- ^ Charles Hellier (2003). Handbook of Nondestructive Evaluation. McGraw-Hill. p. 6.20. ISBN 978-0-07-028121-9.
- ^ Steve Coll (March 12, 2007). "The Unthinkable". The New Yorker. Retrieved 2007-03-09.