Relativistic Electron Dynamics; An upper level laboratory experiment

Union College is home to a series of advanced labs and laboratory equipment, and the department of Physics and Astronomy is no exception.  Laboratory experiences allow student to test the limits of scientific theories and to suggest modifications to those theories through experimentation. One of these experiments involves the dynamics of relativistic electrons.  The relativistic dynamics of an electron beam allows students to measure the momentum (and thus the kinetic energy) of the electrons due to their interaction with an external magnetic field in order to determine the speed of light and the rest mass of the electron.  This laboratory experiment allows one to explore the limits of classical physics and to see the need for relativistic physics. However, the speed of light has been determined in this experiment to be systematically high and an investigation into why this is occurring has been undertaken.   We believe the source of the systematically high values for the speed of light are due to incomplete knowledge of the magnetic field used to steer the electron beam. We will be attempting to map out the exact magnetic field the electron beam interacts with and variations in the magnetic field are believed to be source of the uncertainties in this experiment.