THE COMPTON SCATTERING EXPERIMENT – THE ELECTRON POINT OF VIEW

Arthur Holly Compton was born at Wooster, Ohio, on September 10th, 1892, the son of Elias Compton, Professor of Philosophy and Dean of the College of Wooster. He was educated at the College, graduating Bachelor of Science in 1913, and he spent three years in postgraduate study at Princeton University receiving his M.A. degree in 1914 and his Ph.D. in 1916. In his early days at Princeton, Compton devised an elegant method for demonstrating the Earth's rotation, but he was soon to begin his studies in the field of X-rays. He developed a theory of the intensity of X-ray reflection from crystals as a means of studying the arrangement of electrons and atoms, and in 1918 he started a study of X-ray scattering. This led, in 1922, to his discovery of the increase of wavelength of X-rays due to scattering of the incident radiation by free electrons [1,2]. This effect, nowadays known as the Compton effect, illustrates the particle concept of electromagnetic radiation, was afterwards substantiated by C. T. R. Wilson who, in his cloud chamber, could show the presence of the tracks of the recoil electrons. For this discovery, Compton was awarded the Nobel Prize in Physics for 1927. The original Compton papers deal extensively with the physics of the scattered photons while there is no treatment of the physics of the recoiling electrons. In the current paper we develop a comprehensive treatment of the “electron point of view”, i.e. we treat the dynamics of the recoiling electrons. We proceed by extending the treatment to a much tougher case, the case of inverse Compton scattering, i.e. the scattering of the electrons impacting photons. We conclude with treating the Thomson scattering as a limit case of Compton scattering. The paper is intended for particle physicists who work with particle accelerators as well as graduate students and teachers.