Some design considerations for pbar target sweeping station

This report summarizes the results of some recent calculations useful to design the beam sweeping station to produce high intensity pbar beam at AP0. With various on-going and planned intensity upgrade at the accelerator including the main injector the primary beam intensity on the pbar target is expected to increase. But some complications would arise from the existing method of pbar production. A study of the heavy metal targets used when the beam intensity was about 1.0 x 1012, has shown a clear indication of target destruction by the proton beam. Although the heavy metal has very high melting point temperature the thermoelastic property is not suitable for its use as a reliable pbar target. During 1989 collider run, the target material was changed over to copper because of its better thermoelastic properties. The pbar yield measurement did not show much indications of target destruction except for a small decrease in the pbar yield. However, the calculations showed that the target material along the beam might have had enough energy deposition to transform the target material from the solid state to the liquid state during the beam spill time. A further increase of the proton beam intensity might cause melting of the target and drill a hole. These problems stimulated this investigation of suitable target materials and a method to handle the high intensity proton beam. Properties of a number of target materials have been studied in terms of their mechanical strength/resistance to shock-waves i.e. their thermoelastic behaviour