The induced radioactivity was discovered by French physicists Iren Joliot-Curie (1897-1956) and Frederic Joliot-Curie (1900-1960). The first synthetic nuclear reaction was realized by Rutherford. It is possible to register the charged particles which are taking off at a radioactive decay. It allows to use atoms of the synthetic radioactive isotopes.
There are 2 stages of nuclear reactions.
The first stage of nuclear reaction consists in entrapment by a kern of a particle. For a small time interval the energy is uniformly proportioned between all particles of a compound nucleus.
The second stage of nuclear response (start of a particle from a compound nucleus) occurs as a result of casual diversions from a uniform distribution of energy. There is a time between entrapment of particles and their start from a kern, which is significant more then nuclear time tn = 10-22 s.
All process of nuclear reaction is possible to figure by the formula:
Z1XA1 + a à Z2YA2 à Z3CA3 + b
Z1XA1 - initial kern; a, b - particles;Z2XA2 - compound nucleus; Z3XA3 - terminating kern
Division of kerns.
The heavy kerns are labile. The kern, which was exited as a result of a neutron capture, can be divided into identical parts. The nuclear fission on two debrises is accompanied by eduction of huge energy. The debrises, which are formed at division, are radioactive and can emit neutrons. As the result the exuberant number of neutrons is formed, that gives in radio-activity of yields of decay.