The high-density proportional chamber and its applications

Abstract

The recent development of the high-density proportional chamber - a proportional chamber with solid converters - has provided important, new imaging possibilities for low-energy neutral particles. The principal device realized to date is a high spatial resolution (2 mm fwhm) positron camera. This has been used for angular correlation studies of positron annihilation radiation for condensed matter physics research, and for three-dimensional medical imaging of positron radioisotope distributions. For these applications, a new converter, made of bismuth-doped araldite, is described, which combines good detection efficiency (10%) and coincidence time resolution (100 ns) when operated with carbon-dioxide gas. The addition of a gadolinium foil to a high-density proportional chamber affords an efficient detector for thermal neutrons that maintains the good spatial resolution at large angles of neutron incidence. With a hafnium foil, the same proporties are possible for epithermal neutrons. Solar neutrino detection, electrophoresis, and radiochromatography are other fields of possible application.