MODEL BENCHMARK WITH EXPERIMENT AT THE SNS LINAC

Abstract

The history of attempts to perform a transverse match-ing in the Spallation Neutron Source (SNS) superconduct-ing linac (SCL) is discussed. The SCL has 9 laser wire (LW) stations to perform non-destructive measurements of the transverse beam profiles. Any matching starts with the measurement of the initial Twiss parameters, which in the SNS case was done by using the first four LW stations at the beginning of the superconducting linac. For years the consistency between data from all LW stations could not be achieved. This problem was resolved only after significant improvements in accuracy of the phase scans of the SCL cavities, more precise analysis of all available scan data, better optics planning, and the initial longitudi-nal Twiss parameter measurements. The presented paper discusses in detail these developed procedures.