  This review is concerned with a detailed analysis of some of the technical
problems which arise in the application of the Penning trap method to the
experimental study of neutron $\beta $ -decay,a technique which was first
successfully tested on the low-flux swimming-pool reactor LIDO (capture flux
=3$\cdot 10^6$cm$^(-2)$s$^(-1)$) at AERE Harwell in the 1970's. It does not
discuss the scientific merits or demerits of these studies. Of particular
importance are the trapping and release of neutron decay protons, and the
influence of magnetic mirror effects and radial drifting on the trapped
particles. Since these have energies < 1 keV they must be accelerated to
energies of order 20-30 keV following release, at which point they are recorded
in a silicon surface barrier detector. However serious difficulties were
encountered in the post-release acceleration process with vacuum breakdown in
the presence of crossed electric and magnetic fields.
