This is a process where two nuclei or particles interact to form different particles

In nuclear physics, a nuclear reaction is a process in which two nuclei or nuclear particles collide, to produce different products than the initial particles. In principle a reaction can involve more than two particles colliding,

Nuclear Reaction

Explanation:

When two nuclei or particles move towards each other and, despite the Coulomb repulsion, they get close enough that there is interaction between the particles of one with the particles of the other by the nuclear force, and the formation of different particles and a redistribution of nucleons and a nuclear reaction is said to have occurred.

Nuclear reactions are usually produced by bombarding a target nucleus with a projectile that may be some type of particle or small nucleus, so that Coulomb's repulsion does not become a major obstacle. Reactions involving not very large energies occur in two phases. In the first phase, the target nucleus and the projectile group together, forming what is called a compound nucleus in a highly excited state. In the second phase, the composite core decays by any process that does not violate the conservation principles