EXPERIMENT OF D-T NEUTRON-INDUCED LUMINESCENCE ON WINDOW MATERIALS

A photon measurement system has been developed to analyze wavelength s pectra of photons emitted from window material during D-T neutron irra diation, and the system consisted of a sample holder, a radiation-resi stant optical fiber, a polychromator system and other electronic devic es. High-purity silica glass, synthesized quartz and other optical mat erials were irradiated with D-T neutrons. The luminescence spectrum of the silica glass had a large peak around 450 nm, which was concerned with decay of self-trapped excitons in oxygen vacancies. The intensity of photon emission was proportional to the D-T neutron flux, though t he neutron fluence was too low to damage the sample. Co-60 gamma-ray i rradiation experiments were also performed with the same photon measur ement system. The luminescence efficiency for D-T neutrons has been fo und to be 5 +/- 3 photons MeV-1 in visible range, while that for Co-60 gamma-rays to be 135 +/- 50 photons MeV-1. These data and the related discussions should be useful for the estimation of the photon-noise l evel on optical windows used for fusion plasma diagnostic systems. (C) 1998 Elsevier Science S.A. All rights reserved.