We present studies on electron backscattering from the surface of plastic
scintillator beta detectors. By using a setup of two detectors coaxial with a
strong external magnetic field - one detector serving as primary detector, the
other as veto-detector to detect backscattering - we investigate amount and
spectrum of unrecognized backscattering, i.e. events where only one detector
recorded a trigger signal. The implications are important for low energy
particle physics experiments.Comment: 5 pages, 8 figures; v2: published NIM A versio