Determination of rest mass energy of the electron-an undergraduate laboratory experiment

We present a simple Compton scattering experiment to determine the rest mass energy of the electron which is unique for graduate and undergraduate laboratories. In the present experiment, we have measured the energies of the backscattered gamma photons with an NaI(Tl) gamma ray spectrometer coupled to a 1 K multichannel analyser. In order to enhance the backscattered gamma photons, a thick aluminium target is placed over the radioactive gamma source. The rest mass energy of the electron is determined by using 203Hg, 137Cs, 54Mn and 60Co radioactive gamma sources. The measured values are found to agree with the standard value