Measurement of the quantum efficiency of an electron multiplier as a function of incident proton energy

The quantum efficiency (QE) of an electron multiplier tube with oxidized Cu–Be dynodes was measured for incident protons over the energy region of 0.5–2 MeV at beam currents of 0.1–0.5 nA. The QE is relatively constant with energy up to 1.4 MeV. At higher energy the QE is inverse proportionally to incident energy, dropping to about half the peak value at 2.0 MeV. The proton beam was obtained from a Van de Graaff accelerator at UCLA.