Duduli

Tandem accelerator is a modified form of Van de graaff accelerator.The Van de graaff accelerator is a single stage accelerator while Tandem accelerator is a two stage accelerator.The output energy is double in comparison of Van de graaff accelerator with the same operating voltage.

Van de graaff generator is used to produce a parallel homogeneous beam of charged particles like electrons, protons,α-particles etc. It was developed by van de graaff in 1931 at Princeton university, USA. Principle :- The instrument is based on the following two facts: (i) If a charged conductor is brought into internal contact with a hollow conductor, all of its charge transfers to the hollow conductor, no matter how high is potential of the latter. (ii) The discharge of electricity  occurs readily at pointed objects (corona points).

According to shell model the nucleus consists of protons and neutrons which are placed in certain discrete levels or shells just like the electrons in the discrete shells of an atom.

The phenomenon of spontaneous emission of radiations from the elements much lighter than those occuring in nature by modern techniques of artificial transmutation of elements is known as artificial or induced Radioactivity.

The phenomenon of spontaneous emission of powerful radiations exhibited by the heavier elements found in nature is called natural Radioactivity.

According to tunnel effect, if a particle is impinging (means strike) on a barrier, with energy less than the height of the potential barrier, it will not necessarily be reflected by the barrier but there is always a probability to cross the barrier and continue its forward motion.

The range of α-particles is customarily defined as the distance which these particles travel through air at 76cm of mercury pressure and 15°C temperature before they lose their energy to the extent that they no longer ionise the gas particles. ★The range of α-particles depends upon the following factors (i) Initial velocity of α-particle (ii) Nature of emitting radioactive element (iii) Nature & pressure of the gas or nature of absorber.