Physics Athens 2016

Radioactivity

Stability: equilibrium of forces

Line of stability

Too many neutrons for stability b - decay n=>p + +e - + n H-3, C-14, I-131

• H. Becquerel discovered radioactivity in 1896 • A property of nuclei • Due to inherent physical properties, a nucleus may be not stable and likely to undergo a nuclear transformation. Long ranged Electrostatic forces p • This process can be fast (short half life) or slow (long half life). • The time of transformation cannot be predicted for an individual nucleus - it is a random event which can only be adequately described using statistics Short ranged Nuclear forces p n

Too many protons for stability b + decay p + =>n+ e + + n O-16, F-18 electron capture p + + e - =>n+ n Xe-125 → I-125, Tl-201