Benchmarking of multiparticle phase scan and acceptance scan techniques for the Spallation Neutron Source linac

The importance of accurately setting the RF field amplitude and phase, called the RF set-point is well recognized for a high intensity proton linac such as the Spallation Neutron Source (SNS) linac. Techniques such as phase scan and acceptance scan have been used to determine RF set-points. However, benchmarking study of phase scan and acceptance scan techniques based on experiment was never undertaken before. The benchmarking study demonstrated that the multiparticle phase scan technique based on realistic tracking produces RF set-points consistent with those obtained from the acceptance scan technique. Previous work of phase scan type was based on single-particle tracking and the RF set-point from the single-particle phase scan sometimes did not agree well with either that from the multiparticle phase scan or that from the acceptance scan. The analysis based on multiparticle phase scan showed an accurate agreement between the measurement and simulation even when the beam bunch is rather long (the full-width at half-maximum (FWHM) beam bunch length entering the SNS Drift Tube linac tank 1 is about 27°).