Do radioactive half-lives vary with the Earth-to-Sun distance?

Recently, Jenkins, Fischbach and collaborators have claimed evidence that radioactive half-lives vary systematically over a +/- 0.1% range as a function of the oscillating distance between the Earth and the Sun, based on multi-year activity measurements. We have avoided the time-dependent instabilities to which such measurements are susceptible by directly measuring the half-life of 198Au (t1/2 = 2.695 d) on seven occasions spread out in time to cover the complete range of Earth-Sun distances. We observe no systematic oscillations in half-life and can set an upper limit on their amplitude of +/- 0.02%.