Experience with and studies of the SNS∗ target imaging system

The Target Imaging System (TIS) shows the size and position of the proton beam by using a luminescent Cr:Al2O3 coating on the SNS target. The proton beam hitting the coating creates light, which is transferred through mirrors and optical fibers to a digital camera outside the high radiation area. The TIS is used during operations to verify that the beam is in the right location and does not exceed the maximum proton beam peak density. This paper describes our operational experience with the TIS and the results of studies on the linearity, uniformity, and luminescence decay of the coating. In the future, tubes with material samples might be placed in front of the target for irradiation studies. The simulations of placing tubes in the front of target coating and the effect on the beam width and position measurements are also discussed.