New design features of gas ionization detectors used for elastic recoil detection

Several alternative design features of large acceptance, gas ionization detectors have proven to be successful for application to elastic recoil detection analysis (ERDA). In particular, effects due to the distortion of the entrance field by a large area window have been eliminated in a simple fashion, to allow measurement of the initial rate of energy loss and to provide an energy- and species-independent cathode signal. No less importantly, use of a divided electrode in the anode plane has enabled a more straightforward means of determining the scattering angle that is required for kinematic corrections. An intermediate grid was found to provide a direct and true total energy signal, with only slightly diminished resolution compared with that of the summed total anode equivalent.