2005 Volume 60 Issue 7 Pages 551-554
We have measured the half-life of (1) 7Be encapsulated in C60 and (2) incorporated in Be metal using a HPGe detector with a time reference from a standard-time radio signal. We found that the half-life of 7Be in C60 and Be metal were T1/2=52.68±0.05 and T1/2=53.12±0.05 days, respectively. This 0.83% difference between the EC rate in C60 and in Be metal represents a strong environment effect on the 7Be EC capture rate, caused by the different electronic wave-functions near the 7Be nucleus inside a C60 cage and inside metal Be. Since we have found a record-large environment effect on the decay constant it is our belief that these results will be very useful in further experimental and theoretical studies of environmental effects on radioactive decay.