In close collaboration with researchers from the UK National Physical Laboratory (NPL), scientists from the JRC-IRMM investigated the half-life of thorium-227, for the first time by direct observation of the change in activity with time using a high-purity germanium (HPGe) gamma-ray spectrometer.

With the progress of nuclear medicine in the fight against cancer, new radionuclides are being applied in therapy. The radionuclide 227Th and its daughter nuclide 223Ra are important novel nuclides for alpha immunotherapy. In order to calculate the dose received by the patient, the decay characteristics of these nuclides need to be measured accurately. Scientists from the JRC and the NPL measured the half-life of 227Th, which is one of the essential factors to calculate the patient’s dose as a function of time.
The decay data are also of importance for naturally occurring radioactive materials (NORM), as 227Th is ubiquitously present in soil, water, oil, gas etc. as a decay product of 235U. Due to its many alpha-emitting decay products, it becomes a health risk when it accumulates in certain places where thousands of tonnes of material are being processed.

Read more in: S.M. Collins et al.: “The half-life of 227Th by direct and indirect measurements”, Appl. Rad. Isotop. 104 (2015) 203-211, doi: 10.1016/j.apradiso.2015.07.001