CPB Budapest 2017

Radioactive Decay

He 4 2

Alpha decay

This occurs in very heavy nuclei, with very high atomic number, Z > 82. All nuclides with atomic number higher than 82 are unstable and the majority follow the alpha decay scheme. This is shown in the following equation:

− −

A Z

4A 2Z

4 2

⇒

α Q He + +

parent

daughter

Q α is the disintegration energy which is distributed between the kinetic energy of the emitted α-particle (this represents the majority) and the recoil energy of the daughter nucleus. This means that the emitted α-particles have discrete energy values (hence a discrete energy spectrum) that are lower than the disintegration energy Q α .

226 88

222 86

4 2

Ra ⇒

+ +

MeV 8706 .4 He Rn