  Photon readout of plastic scintillators is investigated with the aim of
improving the precision of neutron \b{eta} decay experiments. Neutron decay is
nowadays studied with high statistics, based on up to 109 registered decay
events, and leads to strongly improved limits on new physics beyond the
standard model, with \b{eta}s often registered in plastic scintillators. The
main systematic errors in these experiments are due to imperfect
characterization of the scintillators with respect to linearity, energy
resolution, and electron backscattering. We study whether these errors can be
diminished when the conventional photomultipliers used for scintillator readout
are replaced by silicon photomultipliers (SiPMs). To this end, various
theoretical and experimental tools are developed, and a procedure for handling
the extreme dark rates of SiPMs is proposed. In \b{eta} spectroscopy, so the
conclusion, plastic scintillator readout with SiPMs can significantly improve
energy response, and help providing reliable corrections for electron
backscattering.
