Studies on (i) Characterization of Bremsstrahlung spectra from high Z elements and (ii) Development of Neutron source using MeV pulsed electron beam and their applications

Particle accelerators which have initially been developed as a tool for basic research now have well known applications in industry, applied sciences and medical. There are more than ten thousand of accelerators running all over the world. Out of which almost fifty percent are devoted to the medical applications. The main areas of use are radioisotopes production, radiography and conventional radiotherapy with electron and photon beams. Electrons and photons are found to be good members of radiation therapy for treating the cancer, quite years ago. This is because of their high penetrability, low Linear Energy Transfer (LET) to exhibit damage to the normal cell and unique characteristics of dose distribution at depth. With the advent of high energy linear and circular accelerators, electron / photon have become a viable option in treating superficial tumors up to the depth of about 5-10 cm. In earlier works, the neutrons produced in reactors or through D-T reaction were mainly used to study the nuclear reactions, measurement of cross sections and elemental analysis in different materials because of their high neutron flux. But, recently the attention has been paid to use these neutrons in various fields such as medical, engineering, defense, geological and industries. The main stream of these applications are irradiation of biological samples, neutron induced damage in an electronic devices, activation analysis, fissile element content determination, detection of explosive class materials, etc. Moreover, the wide range of applications of neutrons have been covered due to their properties such as being a neutral particle with high penetrating power, magnetic moment and comparable wavelength with atomic spacing. This helps to investigate not only the nuclear system but also analysis of materials such as reconstructing the magnetic microstructure, determination of crystal structures, etc. However, in recent years, there have been a rapid growth in case of electron accelerator based neutron sources for medical and industrial applications because of their compactness, easy handling, adjustable flux, no radioactive waste, less shielding requirement, etc. Therefore, in the present thesis considering the importance of electron, photon, fast neutrons and thermal neutrons in the medical and industrial field, the actual evaluation and designing aspect of the associated accessories of the sources have been studied thoroughly. Materials and Methods