Question

Exposure over a number of weeks to 20 MeV alpha particles will make a material radioactive.

True or False?

Answer 1

Radioactive decay occurs in unstable atomic nuclei-that is, once that don't have enough binding energy to hold the nucleus together due to an excess of either protons or neutrons.

It comes in 3 main types - named alpha, beta, & gamma.

Alpha particles are composite particles consisting of 2 protons&2 neutrons tightly bound together. They are emitted from the nucleus of some radionuclides during a form of radioactive decay., called alpha-deacy. An alpha particle is identical to the nucleus of a normal helium atom or doubly ionised helium atom.

Many alpha emitters occur naturally in the environment. For example, alpha particle are given off by uranium-238,radium-226,and other members of the uranium decay series which are present in varying amount in nearly all rocks, soil,and water.

Alpha particles can't penetrate the normal layer of dead cell on the outside of our skin but could damage the cornea of the eye. Alpha particle radiation is normaly only a safety cocern if the radioactive decay occurs in an atom that is already inside the body or inside cell. Alpha particle emitters are particularly dangerous if inhaled, ingested, or if they enter a wound.

Alha particle are highlyionising because of their double positive charge, largemass and because they are relatively slow. They can cause multiple ionization within a every small distance. This gives them the potential to do much more biolagical damage for the same amount of deposoted energy. Alpha articles, because they are highly ionising, are unable to penetrate very far through matter and are brought to rest by a few centimere of air or less than a tenth of a millimetre of living tissie.

From various alpha emiters, kinetic energy of alpha particles emitted is of the order of 4.9Mev.studies reveal that nucleus of alpha emitters behaves as a potential barrier of height of the order of 25Mev.

Classically its is impossible to account for the emission of an alpha particle of insufficient energy (=4-9Mev),crossing such a high potential barrier(=25Mev).