Absence of low-temperature dependence of the decay of Be7 and Au198 in metallic hosts

The electron-capture (EC) decay rate of Be7 in metallic Cu host and the β - decay rate of Au198 in the host alloy Al-Au have been measured simultaneously at several temperatures, ranging from 0.350 K to 293 K. No difference of the half-life of Au198 between 12.5 K and 293 K is observed to a precision of 0.1%. By utilizing the special characteristics of our double-source assembly, possible geometrical effects that influence the individual rates could be eliminated. The ratio of Be7 to Au198 activity thus obtained also remains constant for this temperatures range to the experimental precision of 0.15±0.16%. The resulting null temperature dependence is discussed in terms of the inadequacy of the often-used Debye-Hückel model for such measurements.