The scientists registered 128 alpha-particle events over 5 days and found an unexpected line in the spectrum at 3.14 MeV – now attributed to bismuth-209 decay. The half-life was calculated to be (1.9 ...

Radioactive decay is ubiquitous. It occurs everywhere on Earth and throughout the universe. The most common forms occur when an unstable nucleus spits out an alpha particle, consisting of two neutrons ...