Shielding and Handling of Targets for a High Intensity Radioactive Ion Beam Facility

Abstract

There has been a steadily growing worldwide interest in generating accelerated beams of unstable nuclei for use in a variety of applications such as nuclear physics, nuclear astrophysics, atomic and condensed matter physics, and medicine. A number of facilities, either planned or under construction, will couple an intense production source of unstable elements to an efficient accelerator in order to produce accelerated ion beams of a wide range of nuclei far from stability. We describe here the production targets and their shielding as designed and constructed for ISAC, the high-intensity accelerated radioactive ion beam facility at TRIUMF.The shielding for the targets is integrated into each target module so that all services and radiation-sensitive connections are made outside the shielding and the vacuum enclosure. This allows the use of, for example, elastomer seals for the vacuum connections. Including the weight of the steel shielding, each target module weighs approximately 15 tonnes. For servicing, the target modules are removed vertically by a remotely operated crane. The modules may then be transported either to one of two hot cells for maintenance or to a storage silo. The remotely controlled transport takes place in the Target Maintenance Hall. This is a shielded, ventilated building that allows the target modules to be transported without shielding for the induced radioactivity.We also present some observations of experience during the initial commissioning at low and medium proton beam intensities.