In 1919 Rutherford performed the first artificial nuclear reaction. He was able to demonstrate that when $$α$$ particles are introduced into a closed sample of N2 gas, an occasional collision led to the formation of an isotope of $$\ce{O}$$ and the release of a proton:
$\ce{_{2}^{4}He + _{7}^{14}N -> _{8}^{17}O + _{1}^{1}H} \label{1}$
Since then many thousands of nuclear reactions have been studied, most of them produced by the bombardment of stable forms of matter with a beam of nucleons or light nuclei as projectiles. Particles which have been used for this purpose include protons, neutrons, deuterons (21H) , $$α$$ particles, and B, C, N, and O nuclei.