A simplified relativity experiment

We describe a simplified experiment that can be used to verify the relativistic energy-momentum relationship for beta particles emitted from a 204Tl source. The experiment makes use of an exempt radioactive source and is therefore ideal for institutions that do not maintain a Nuclear Regulatory Commission (or state) license. The relativistic beta particles are injected into a uniform magnetic field and the maximum radius of the trajectories is determined. Comparing this radius to the relativistic and non-relativistic predictions demonstrates that only the relativistic equations are consistent with the data. The simplicity of the experiment and analysis makes this project ideal for inclusion in a sophomore-level modern physics course.