This book is based on the lectares on experimental nuclear physics delivered by the author for many years at various faculties of the Moscow Physical Engineering Instilale. As was mentioned in the Preface to the Fourth Russian Edition, the main emphasis is laid od the description cf basic experiments in nuclear physics and their interpretation on the basis of the symmetry of the laws of nature. A simple theoretical interpretation is also presented, which, however, cannot replace a serious theoretical source on nuclear physics.The author believes, however, that an analysis of t ie basic con­ cepts of the theory together with experiments will help generate a deeper understanding of Lhe physics of the phenomena under con­ sideration. Besides, such a presentation Makes Iho book suitable foe self-education.The translation is based on the latest Russian edition (1983). Nnertheless, the material was updated for the present publication. The first volume ij supplemented hy information concerning the discovery of new types of radioactivity. Tlie second volume contains new material on the discovery of intermediate vector bosons. Besides, redundant material and topics of no interest to English-speaking readers have been omitted. Misprints and errors noted in the Russian edition have been corrected. Translated from Russian by Ram S. Wadhwa, Ph.D.First published 1987Revised from the 1983 Russian editionNote: The scan quality is poor, the page sizes are mismatched and some pages may be missing.