Response of a thin avalanche detector to simultanous minimum ionizing particles

A thin multiwire avalanche detector, operating in the saturated mode, has been constructed and tested for its response to 1 and 2 (simultaneous) minimum-ionizing particles. These measurements employed the 19F(p,α)16O reaction to form the Jπ = 0+, Eex = 6.05 MeV level of 16O, which deexcites 100% by nuclear pair emission yielding energetic β+-β− pairs. The result peak detector pulse amplitude is directly proportional to n, the number of particles, for n ≤ 2, whereas the fractional resolution (FWHM/PEAK) is approximately proportional to 1√n.