Fundamental study of a new radiation imaging system using a grid-type scintillating device

High-resolution neutron imaging is desired in various fields, including those of materials sciences and medical diagnostics. The authors propose a new radiation imaging system using a grid-type device. The final system comprises a flat scintillator and a grid-type device with wavelength shifting polymer (WLSP) between the grids. The authors demonstrate in this study that the grid-type device functions as a two-dimensional (2D) waveguide and is applicable to radiation measurements. Scintillator resin, instead of WLSP, was polymerized in a metal grid. Scintillation photons are transmissible in two directions along the grid channels, which serve as waveguides. Clear optical fibers at the ends collect the photons. We evaluated the imaging capability using measurements with a ⁹⁰Sr/⁹⁰Y beta source. The channel pitch was 1.0 mm; the grid wall was 0.2 mm thick. Beta rays were collimated using a 10-mm-thick aluminum plate with a 1-mm-diameter hole. Results show that this structure measures 2D radiation distributions with a full width at half maximum (FWHM) of about 1.2 mm in both directions. Furthermore, we performed experiments using a fast neutron beam. From those results, we infer that this system is useful for radiation imaging, showing a good linear relationship to the source intensity. This grid-type device is a useful new radiation imaging tool. (author)