198Au

198Au is a radioactive isotope of gold with atomic number 79 and mass number 198. It has a half-life of about 2.7 days and decays by beta-minus emission to stable mercury-198, accompanied by gamma radiation that allows detection and measurement.

Production of 198Au typically occurs in a nuclear reactor by neutron capture on 197Au, via the reaction 197Au(n,γ)198Au. It is produced in quantities suitable for research or medical use and is then separated chemically from the target material. The isotope is synthetic and does not occur naturally in any significant amount.

In terms of nuclear properties, 198Au emits beta particles and gamma rays during its decay, which makes it useful as a radiotracer and as a source for gamma spectroscopy, imaging, and calibration applications. Historically, gold-198 has been explored for biomedical research, including radiotracer studies, and in some therapeutic contexts. Colloidal formulations of gold-198 have been investigated for targeted radiotherapy in experimental settings, though such uses are largely of historical or niche interest today.

Safety and handling considerations are typical of short-lived radiopharmaceuticals and sealed radioactive sources. Shielding and secure storage are required, and regulatory disposal procedures apply after use. The relatively short half-life means activity decreases relatively quickly, reducing long-term waste but requiring timely production, handling, and use to maximize efficacy.

See also: 197Au, 199Au, and other gold isotopes.