Measurement of the Beta Spectrum with a Geiger Counter and a Magnet

The energy spectrum of the electrons emitted by a beta radioactive source may be measured, to some extent, deflecting them by an appropriate magnetic field and using a simple Geiger counter —not able by itself to measure the energy—as a device which merely counts the number of particles following a given trajectory. The requirements to make such a measurement are discussed, and an example is given of a dataset obtained by the use of a commercial apparatus.