Scintillation detector with wavelength-shifting optical fibers

Abstract

A radiation detector includes wavelength-shifting optical fibers which are selected and arranged to capture a greater percentage of visible photons through the use of two or more different color stages of wavelength-shifting fibers. A primary set of optical fibers contains a first wavelength shifting optical fiber tuned to absorb photons emitted by the detector crystal and to re-emit photons at a longer wavelength. At least some of the re-emitted photons from the primary set of optical fibers are captured and transmitted down the first wavelength shifting optical fiber. A secondary set of optical fibers contains a second wavelength shifting optical fiber tuned to absorb photons emitted by the primary set of optical fibers and to re-emit photons at a still lower frequency. In this way at least some of the photons emitted by the primary set of optical fibers and not transmitted down the first optical fiber are captured and transmitted down the secondary optical fiber. An electro-optical device such as a PMT or photodiode is positioned to detect photons received from at least one end of the first or second wavelength shifting optical fibers and to generate an electrical signal in response.