With the final goal to prove the feasibility of using TESs as low energy electron spectrometers, TES4e will develop TESs with two distinct designs: one will work in the range 0-1000 eV with an energy resolution FWHM around 500 meV, while the other will be optimized for energies in the range 0-50 eV and will provide a better energy resolution of the order of 100 meV. Energies below 1 keV are the typical energies of the primary beams for X-ray photoelectron spectroscopy, Reflection Electron Energy Loss Spectroscopy, Auger Electron Spectroscopy and Low Energy Electron Microscopy. The TES4e detectors energy resolution and response function will be assessed in the corresponding energy range of interest. Also, as innovative tool for high resolution spectrometry of low energy electrons TES4a might have an impact on particle physics. This will prove crucial, for instance, in experiments measuring low energy electrons in emitted by tritium in PTOLEMY, either due to inverse beta decay, as in Cosmic Neutrino Background searches, or by beta decay in small scale prototypes exploited for a direct neutrino mass experiment.

Participants: University of Milano-Bicocca (Angelo Nucciotti, PI), National Metrology Institute of Italy - INRiM (Mauro Rajteri, local project leader),