A detector has been developed that has an efficiency greater than 95%
for a variety of ions that strike it with energies of more than a few
keV. The efficiency is constant over the large entrance aperture (2.5
cm diameter) and for particle fluxes up to 4 x 10(4) s-1. An important
feature is the ability to identify correlated pairs of particles that
arrive as little as 30 ns apart, even in the presence of large, uncor
related backgrounds.