Practical transverse matching of the high-intensity SNS Linac

It is important to accomplish adequate matching for a high intensity linear accelerator such as the SNS linac to minimize the mismatch and potential beam loss. In the early stage of the SNS linac design, there was a discussion over whether to match the core or to match the tail. The present study shows that the matching by minimizing rms emittances reduces both the core emittance and the beam tail, providing a stable and unambiguous matching for the SNS Drift Tube Linac, when an emittance scanner is available. For the transverse matching of other sections of the SNS linac where only wire-scanners are available, we use beam size data obtained from multiple wire-scanners installed in series to do the matching with the help of an envelope code such as Trace3D. It is verified that matching is improved through the matching technique based on the beam profile measurements from wire-scanners in series.