Nondestructive Bunch Shape Monitor of a Negative Hydrogen Beam using a Laser Pulse Train for High-Intensity Proton Accelerators

Abstract In high-intensity proton accelerators, it is crucial to identify and reduce sources of beam loss, which requires rapid measurement of the beam distribution in both position and velocity space. In this study, we have developed a completely new nondestructive bunch shape monitor that measures the longitudinal distribution of the H$^{-}$ (negative hydrogen) beam by using repetitive laser pulses and measuring the amount of the photo-detached beam. A proof-of-principle experiment successfully measured the longitudinal beam profile of the 3 MeV H$^{-}$ beam at the test accelerator of J-PARC. This paper describes the concept of the monitor, presents the measurement results, and discusses its applicability to future beam diagnostics.