A beam characterization of H- particles

A pinhole-scintillator diagnostics system has been developed to determine the characteristics of a 50-MeV H^- beam. The device consists of an aluminium plate (1.27 mm thick) with a series of pinholes (125-μm diameter) covered by a thin neutralizer foil, and a downstream scintillator plate and associated camera. The foil-covered pinholes produce a series of H⁰ beamlets that are detected downstream by the scintillator plate. The use of H⁰ particles allows measurement of the beam parameters without changing the magnetic fields of downstream magnetic elements. Measuring the intensities of the beamlets and the beamlet width allows determination of the beam parameters. The H⁺, produced by the plate, are sufficiently scattered by the plate, such that a sweep magnet is not required,. The device has been used at the Argonne National Laboratory (ANL) Neutral Particle Beam Test Stand (NPBTS) to measure the parameters at the input of the beam expanding telescope