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Introduction

In 1911, Ernest Rutherford (1871–1937) and his assistants Hans Geiger (1882–1945) and Ernest Marsden (1889–1970) performed a series of experiments that marked the beginning of modern particle physics, the quest to unravel the mysteries of the structure of matter. At that time it was believed that an atom was a sphere of positive charge of diameter of about 10−10 m with the electrons moving inside the sphere. This picture is the Thomson model of the atom. This is the picture of the atom that the Rutherford experiment challenged.