Abstract
A transverse beam profile monitor that visualizes a two-dimensional beam-induced fluorescent image was developed. The monitor employs a sheet-shaped gas flow formed by a technique of rarefied gas dynamics. A simplified analysis method was developed to reconstruct the beam intensity profile from the obtained image. The developed profile monitor and the analysis method were applied to measure the J-PARC 3 MeV ${\mathrm{H}}^{\ensuremath{-}}$ beam profile. The root mean square values of the profiles were consistent with the ones obtained by a wire-scanning-type beam profile monitor. The beam loss due to the gas sheet injection was measured as a beam-current reduction. The amount of the beam current decreased in proportion to the gas sheet flux and the reduction ranged from 0.004 to 2.5%. The assembled system was capable of reconstructing a beam profile from a single shot beam pulse ($1.7\ifmmode\times\else\texttimes\fi{}{10}^{13}$ protons in $50\text{ }\text{ }\ensuremath{\mu}\mathrm{s}$).
Highlights
Measurements of high-intensity high-energy beams in a particle accelerator often cause losses of beams and activations of nuclear radiation of the accelerator system
A beam diagnostic system that minimizes the beam loss is to be realized for monitoring the beam operation of a highintensity high-energy accelerator
We report the effectiveness of the photon-detection-type gas sheet monitor based on the experiment results using the J-PARC 3 MeV H− beam from the following viewpoints: (i) reconstruction of a beam spatial distribution from a photon emission signal spatial distribution; (ii) comparison of a beam profile obtained by a gas sheet monitor using photons with a beam profile obtained by a wire scanner monitor; and (iii) discussion on merits and issues of the developed gas sheet profile monitor system
Summary
Measurements of high-intensity high-energy beams in a particle accelerator often cause losses of beams and activations of nuclear radiation of the accelerator system. The beam pulse length must be shortened compared with the standard length because the wire breaks by the energy deposited from the beam particles. We are developing a nondestructive beam profile monitor system using a gas sheet to reduce the beam loss and improve the quality of the beam measurement. Nondestructive beam profile monitors that detect charged particles, such as ions and electrons, or photons produced by beam-gas interaction are being developed in many research institutes.
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