Comparison of the alpha-decay half-life of Po-210 implanted in a copper matrix at 4.2 and 293 K

In light of recent speculations on a potentially increased speed of the radioactive decay of α-emitters embedded in a metallic matrix at very low temperature, four high-purity Cu disks deep-implanted with 209Bi were prepared. The disks were irradiated in a high-flux reactor to transmute the 209Bi into 210Po. After the irradiation, the 210Po activity was measured for all four disks. While two of the disks were stored at room temperature, the other two disks were stored in a sealed container submerged in liquid helium (T = 4.2 K) for approximately 200 days. After the storage time the 210Po-activity measurements were repeated and the 210Po half-life was calculated for each sample. No difference between the half-lives for the four samples could be detected within the uncertainties of the measurements. In other words, the results of this study show no evidence for an increase of activity for α emitters embedded in a metallic matrix at very low temperature.