Artificial transmutation is the conversion of one element into another by artificial methods. The first successful artificial transmutation was carried out by Rutherford. When nitrogen was bombarded with α-particles of sufficient energy, a rare isotope of oxygen (8O17) and a proton were formed.
7N14 + 2He4 - - > 8O17 + 1H1
This process is called nuclear reaction.
In a nuclear reaction, the sum of initial atomic numbers (charges) is equal to the sum of the final atomic numbers, i.e conservation of charges is satisfied. In the same way, conservation of nucleons is also satisfied. But the initial rest mass is not equal to the final rest mass. The energy equivalence of the difference between the rest masses is equal to the nuclear reaction energy Q. The nuclear reaction can be written as
A + a → B + b + Q
where A is the target nucleus and a, the bombarding particle. B and b are the product nucleus and particle.
A particle accelerator is a device used to accelerate the charged particles, which are required in the study of artificial transmutation of elements. Hence the accelerator is the basic device in high energy particle physics.
Accelerators can be divided broadly into two types.
1. The first type belongs to electrostatic accelerators in which charged particles are accelerated by applying a constant potential difference. The final energy is determined by the amount of the potential difference. The Cockcroft - Walton and Van de Graaff generators belong to this class. These accelerators can accelerate particles only upto a few million electron-volts.
2. energy of the order of 109 eV (GeV), of course, with each machine having its own energy limit.
The second type is the cyclic or synchronous accelerator, which accelerate particles in multiple steps imparting a small energy in each successive step. Example : Linear accelerator, cyclotron, betatron, synchrocyclotron and synchrotron. They can accelerate particles to energy of the order of 109 eV (GeV), of course, with each machine having its own energy limit.