Various Applications of Precision Low-Energy Nuclear Electron Spectrometry in the KATRIN Tritium Neutrino Project

摘要

The energy scale of the main spectrometer in the KATRIN tritium project is required to remain stable within +/- 60 meV at an electron energy of 18.6 keV for two months in order to reach the intended sensitivity of 0.2 eV for the rest mass of the electron antineutrino. A natural source of reference electrons with an energy of 17824.3 +/- 0.5 eV based on K-conversion electrons of the 32-keV nuclear gamma-transition in Kr-83m from the decay of parent Rb-83 was developed for this purpose using precision low-energy nuclear electron spectrometry. The spectroscopic parameters of Kr-83m/Rb-83 sources fabricated by ion implantation into polycrystalline platinum foils were significantly better than the parameters of vacuum-deposited sources. A large-scale study of the influence of the physicochemical environment of atoms of different radioisotopes in various matrices of vacuum-deposited and implanted radioactive sources on the energy of emitted conversion and Auger electrons and on the structure of the corresponding energy spectra was conducted in the process. The possibility of application of photoelectron sources with a metallic converter as sources of reference electrons for the KATRIN project was also considered.