Soon after the discovery of radioactive decay, nuclear reactions
induced by radioactive rays were observed. A keen sense of observation
and accurate conclusion are the key to these discoveries.
In 1919, E. Marsden and
E. Rutherford saw some tracks of positively
charged particles that were different from those of alpha particles,
in the vicinity of the alpha particle source.
They concluded that "the nitrogen atom is disintegrated under the
intense force developed in a close collision with a swift alpha particle".
14N (a, p) 17O
Soon after, F. Joliot and I. Curie discovered the reaction,
27Al (a, n) 30P
( , b+ or EC) 30Si
around 1929 when
John D. Cockroft and Ernest T.S. Walton devised
an accelerator in the Cavendish Laboratory, Cambridge, England.
They achieved the reaction
7Li + p ® 2 a
They have smashed the lithium atom into two pieces by energetic proton.