J. Goodwin

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

Recently, Jenkins, Fischbach and collaborators have claimed evidence that radionuclide 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 (198)Au (t(1/2)=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%.

Precise half-life measurement of the superallowed beta(+) emitter (26)Si

We have measured the half-life of the superallowed 0+ -to- 0+ beta+ emitter 26Si to be 2245.3(7) ms. We used pure sources of 26Si and employed a high-efficiency gas counter, which was sensitive to positrons from both this nuclide and its daughter 26mAl. The data were analyzed as a linked parent-daughter decay. To contribute meaningfully to any test of the unitarity of the Cabibbo-Kobayashi-Maskawa (CKM) matrix, the ft value of a superallowed transition must be determined to a precision of 0.1% or better. With a precision of 0.03% the present result is more than sufficient to be compatable with that requirement. Only the branching ratio now remains to be measured precisely before a +/-0.1% ft value can be obtained for the superallowed transition from 26Si.

Half-life of the electron-capture decay of 97Ru: Precision measurement shows no temperature dependence

We have measured the half-life of the electron-capture (ec) decay of

Precise half-life measurement of the superallowed β + emitter 46 V

^{97}\mathrm{Ru}

Tests of nuclear half-lives as a function of the host medium and temperature: Refutation of recent claims

in a metallic environment, both at low temperature

Precise half-life measurement of the superallowed beta(+) emitter (10)C

(19 \mathrm{K})

Precise Half-Life Measurement of the Superallowed beta emitter 10C

, and also at room temperature. We find the half-lives at both temperatures to be the same within

Precise half-life measurement of the superallowed β+ emitter 38Ca

0.1%

The half-life of 198Au : High-precision measurement shows no temperature dependence

. This demonstrates that a recent claim that the ec decay half-life for

Measurement of the half-life of

^{7}\mathrm{Be}