Characterisation of a Thick Pixelated Silicon Detector for Electron Spectroscopy of Neutron Beta Decay

Silicon detectors are commonly used for spectroscopy of low-energy particles.

For electrons in the 1 MeV range, a rather large thickness of 2mm is required to entirely stop the electrons and commercial options are scarce.

With the instrument PERC at the FRM II, we aim to measure beta spectra from polarised and unpolarised neutrons in order to determine the axial-vector coupling constant, the element $V_\textrm{ud}$ of the Cabibbo-Kobayashi-Maskawa quark-mixing matrix, and to search for hypothetical scalar and tensor contributions.

We present the characterisation of a commercially available, pixelated detector to assess its suitability to measure the entire electron energy spectrum of free neutron beta decay.