ABSTRACT
More than 11 decades have elapsed since the discovery of radioactivity. During this time, numerous natural or articial sources of radiation have been discovered or invented, beginning from radium and Roentgen x-ray machine to the neutron generator and synchrotron radiation. The applications as well as hazards of these types of radiation depend on their physical nature, including charge, mass, and energy. Scientists spent most of their time studying its properties, action and interaction, applicability for public well-being, and ways to avoid its hazards. At the atomic scale-which is best studied in the gaseous phase-interaction of radiation with atoms had led to the emergence of quantum mechanics. In this situation, the interaction regimes are the energy transfer by Coulomb excitation, photo-electron emission, and Compton scattering, or matter production and annihilation. On the other extreme, when all the energy and mass of the radiation are absorbed by the material, the bulk material may change its macroscopic properties, at least its temperature, as a consequence of being subject to irradiation.
