Abstract
The shape of the spectrum corresponding to the electrons emitted in $\beta$
decay carries a wealth of information about nuclear structure and fundamental
physics. In spite of that, few dedicated measurements have been made of
β-spectrum shapes. In this work we present a newly developed detector for
β electrons based on a telescope concept. A thick plastic scintillator is
employed in coincidence with a thin silicon detector. First measurements
employing this detector have been carried out with mono-energetic electrons
from the high-energy resolution electron-beam spectrometer at Bordeaux. Here we
report on the good reproduction of the experimental spectra of mono-energetic
electrons using Monte Carlo simulations. This is a crucial step for future
experiments, where a detailed Monte Carlo characterization of the detector is
needed to determine the shape of the $\beta$-electron spectra by deconvolution
of the measured spectra with the response function of the detector. A chamber
to contain two telescope assemblies has been designed for future β-decay
experiments at the Ion Guide Isotope Separator On-Line facility in
Jyväskylä, aimed at improving our understanding of reactor antineutrino
spectra.