Hi aspirant,

Radioactive disintegration is synonym for radioactive decay . This occurs when an atom has an unfavourable or unstable combination of protons en neutrons in its nucleus and/or has excess energy. Radioactive decay is a spontaneous process in which the unstable nucleus emits its excess energy in the form of radiation. The three most common types of radioactive decay are alpha, beta, and gamma.

Alpha- In alpha decay, the nucleus emits an alpha particle, or a particle containing two protons and two neutrons. The nucleus is said to decay, or change into one that is a little lighter, one with four less particles.

Beta- Beta decay is when a nucleus decays spontaneously by emitting an electron or a positron. This is also a spontaneous process, like the alpha decay, with a definite disintegration energy and half-life. And, it follows the radioactive laws. A Beta decay can be a beta minus or a beta plus decay.

Gamma- a nucleus has energy levels too. When a nucleus is in an excited state, it can transition to a lower energy state by emitting an electromagnetic radiation . Further, the difference between the energy states in a nucleus is in MeV. Hence, the photons emitted by the nuclei have MeV energies and called Gamma rays.

Hope this helps.