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

Half-life of the electron-capture decay ofRu97: Precision measurement shows no temperature dependence

“…As a byproduct of this primary measurement, we also obtained half-life data for two β − emitters, 103 Ru and 105 Rh, at room temperature and 19 K. These results, though slightly less precise than our measurements on the β − decay of 198 Au [9], nevertheless confirm our previous conclusion for that decay mode. With any temperature dependence for β + decay also now ruled out at the 0.04% level [11], it has become clear that there is no reason to doubt the accuracy of nuclear weak-decay half-lives that have been quoted over the past decades with subpercent precision and without accounting for the host material or temperature.…”

“…By keeping our system dead time below about 4% and recording all our spectra for an identical pre-set live time, we ensured that our results were essentially independent of dead-time losses. However, at a precision level of 0.1% or better, pile-up can also become an issue, so we carefully tested our system for residual rate-dependent effects, as reported in our previous article on 198 Au [9]. We first measured the 662-keV γ -ray peak from a 137 Cs source alone, and then remeasured that source a number of times in the presence of a 133 Ba source, which was moved closer and closer to the detector in order to increase the dead time and the number of chance coincidences.…”

“…Based on this concern, we first repeated the measurement on the decay of 198 Au(t 1/2 = 2.7 d) in gold [9]. While the original measurement by Spillane et al [4] followed the decay for only a little over one half-life, we recorded the decay with much better statistics for over ten half-lives at both room temperature and at 19 K. Our results showed the half-lives at the two temperatures to be the same within 0.04%, a limit two orders of magnitude less than the difference claimed by Spillane et al This null result was subsequently confirmed by two other measurements of 198 Au, which set limits of 0.13% in a Al-Au alloy host [10] and 0.03% in gold [11].…”

Absence of low-temperature dependence of the decay ofBe7andAu198Kumar1, Hass2, Nir-El3 et al. 2008Phys. Rev. C233110View full textAdd to dashboardCite

“…Note added: After submission of this manuscript, a new measurement on the T -dependence of the half-life of 198 Au has been published [27], in excellent and full agreement with the present null effect.…”

Measurement of the half-life ofAu198in a nonmetal: High-precision measurement shows no host-material dependence

“…The corresponding measured numbers as reported by Spillane et al, were 0.4(7) and 4.0(7)%. We repeated their measurement in a metal at two different temperatures and have already reported [4] Au. To obtain comparable conditions and statistics for our measurement in a non-metal, we wished to use neutron activation again and sought a suitable gold compound that is also an insulator.…”