Question

Why is alpha particle 4he2 appear in many binary nuclear reaction?

Answer 1

Alpha particles are helium nuclei, consisting of 2 protons and 2 neutrons. This nuclide is very stable, and helium is a rather abundant element at a universal scale. Many heavy elements such as ²³⁸U and ²³⁹Pu emit an alpha particles, ⁴He². For example:

238U92 = 234Th90 + 4He2 + Energy
235U92 = 231Th90 + 4He2 + Energy
239Pu92 = 235U92 + 4He2 + Energy
226Ra88 = 222Rn86 + 4He2 + Energy

Most of the energy is carried away by the alpha particles in the form of kinetic energy. The particles move at high speed when emitted. Most alpha emitters are elements heavier than lead. Some rare earth elements also emitts alpha particles.

Many nuclei with mass numbers greater than 200 undergo alpha (α) decay, which results in the emission of a helium-4 nucleus as an alpha (α) particle.