This book includes to-the-point description of titles, related theories, labelled diagrams, tables, examples, etc. This book is beneficial for B.Tech. Physics, B.Sc. Physics and for M.Sc. Applied Physics students. It helps students to prepare for JAM, NET SET exams. This book has been divided into nine chapters. Topics like nuclear structure, nuclear reactions, radioactivity, elementary particles, accelerators, radiation detection, interaction of radiation, cosmic rays are covered in detail. The discussion on all the topics is simple and mathematical derivations are less complex. Data, graphs and figures are mentioned wherever required. It also includes the basic lab experiments required in the nuclear lab for both B.Sc. as well as M.Sc. students.