High Spatial Resolution in $\beta$ -Imaging With a PIM Device

The autoradiography is an imaging technique able to locate in 2 dimensions molecules labeled with beta radioactive emitters. The usual technique in use is based on solid device, mostly films or phosphor screens. We report on tests performed with PIM (parallel ionization multiplier) on microscope slides demonstrating that MPGD (micro pattern gas detector) incorporating micromegas micro-meshes have to be considered for a next generation of beta-imager. The main advantages come from the high spatial resolution measured (25 mum FWHM in two dimensions) and from the event by event reconstruction position measurement resulting in ldquoon-linerdquo imaging availability in which no ldquoafter developmentrdquo have to be performed.