Electron line shape of the KATRIN monitor spectrometer

Conversion electrons emitted from Kr-83m implanted into a solid substrate will serve as a powerful tool for monitoring of the energy scale stability in the KATRIN neutrino experiment. An appropriate description of the conversion line shape is essential to determine the energy of the emitted electrons. It is shown that the Doniach-.Sunjic line shape gives a significantly better fit to the conversion electron spectra than the previously used double Voigt model. The electron spectra were obtained with the KATRIN MAC-E filter monitor spectrometer.