Preparation of paper scintillators and their effective use in radiation testing for α- and β- particles in radioactive liquid, solid, and gas contaminants.

A paper scintillator, which is composed of an organic scintillator encapsulated in silica nanoparticles adsorbed on three types of micrometer-size silica fine powder (scintillator-silica FP), was prepared by a paper making method. The scintillator-silica FP was found to be distributed throughout the paper scintillator, as shown in its emission images. Surface photoluminescence spectra depended on the amount of scintillator-silica FP and were assigned to the radioluminescence excited upon irradiation with β-particles of 45Ca. The onset channels of the pulse height spectra of 3H, 63Ni, 14C, 45Ca, 204Tl, and 32P indicated their dependence on linear energy from 18.6 to 1711 keV using the H mode in LSC-7400 for the paper scintillator to detect their maximum β-particles energies. The paper scintillator could also detect α-particles from 211At, and its pulse height spectrum was wider than that of a liquid scintillator (LS). Radon gas in air was collected using a gas sampler with the paper scintillator, and radiation from daughter nuclides was detected for 10 days. The adsorption/absorption of tritiated water onto/into the paper scintillator after dipping, dropping, and immersing the paper scintillator into tritiated water led to the detection of β-particles under different conditions of tritiated water for determining whether the radioactivity in the solution, is high or low. The paper scintillator smeared with tritiated contaminants detected tritium without requiring an LS, which is used in a smear paper.