High-precision measurement of the half-life of 147Sm

The half-life of the long-lived isotope 147Sm was determined by means of activity determination using liquid scintillation counting. The amount of samarium was determined by ICP-OES using a NIST reference standard. The isotopic ratio N(147Sm)/N(Sm) of the samples was measured by means of ICP-HRMS. The half-life was found to be 1.070(9)×1011 y. The result is in good agreement with other evaluations and the relative standard uncertainty of 0.8% is lower than in any previous work.