Response function measurement for a non-destructive gas-sheet beam profile monitor.

A gas-sheet beam profile monitor enabling non-destructive two-dimensional profile measurements of a high-intensity beam by capturing an image of a beam-induced fluorescence was developed. For quantitative profile measurements, the monitor's response function comprising, e.g., the gas sheet density distribution and the detector's sensitivity distributions must be experimentally clarified because the monitor output is a converted profile with the response function. A response function measurement method was devised based on the beam-profile-measurement method formula of the monitor. The response function was obtained by injecting a thin electron beam into the developed monitor and scanning its center position in transverse. The measured response function was evaluated by the J-PARC 3 MeV, 60 mA H- beam profile measurement. The 2-D beam profile was successfully reconstructed with the measured response function within the 2.74% residual of the least-squares method and 6.01% experimental statistic deviation. The projected 1-D profiles agreed well with those measured using a wire-scanning-type profile monitor.