Abstract: A plastic scintillating fiber according to an aspect of the present invention includes: an outermost peripheral layer containing a fluorescent substance that emits scintillation light when it is irradiated with at least one of neutron radiation and heavy-particle radiation; a core disposed inside the outermost peripheral layer and containing at least one type of fluorescent substance that absorbs the scintillation light and wavelength-converts the absorbed light into light having a wavelength longer than that of the absorbed light; and a cladding layer covering an outer peripheral surface of the core and having a refractive index lower than that of the core. A wavelength shifting fiber including the core and the cladding layer, and the outermost peripheral layer covering an outer peripheral surface of the wavelength shifting fiber are integrally formed.

Abstract: Provided is a plastic scintillating fiber having a circular cross-section, in which a reduction in light emission amount depending on the radiation crossing position can be suppressed. A plastic scintillating fiber according to one aspect of the present invention is a plastic scintillating fiber having a circular cross-section, the plastic scintillating fiber including: a core which contains a fluorescent agent having ultraviolet absorption and luminescence properties; and a clad which covers the outer peripheral surface of the core and has a lower refractive index than that of the core. The concentration of the fluorescent agent in the core is distributed such that it increases from the center toward the outer periphery in a cross-section of the core.