High resolution and two-dimensional focal plane detector for intermediate energy heavy ions

A large-area, high-resolution two-dimensional position sensitive gas detector has been developed for intermediate energy heavy ions. The x position information is obtained by a multi-cathode read-out method and the y position by measuring the drift time of electrons. This detector has no left-right ambiguity and very little dead layer in the sensitive area, resulting in a detector system which is thin and homogeneous in the whole sensitive area. The overall position resolution of 0.20 and 0.4 mm (FWHM) were obtained for x and y directions, respectively. The position resolutions at lower gas pressure were also measured to find an optimum operating condition to reduce multiple scattering effect from the window foils and the detector gas. This detector has been shown to be very useful for high-resolution heavy ion experiments at intermediate energies.