Organic scintillators for neutron detection

The goal of the present work has been to develop a method for the efficient and reliable production of gadolinium and boron-containing solid scintillators. Polyvinyl toluene, silicone rubber, and other materials were investigated. Gadolinium in a solid overcomes the limitations of the physical form of a liquid, and silicone rubber as a carrier for either gadolinium or boron overcomes the thermal limitations of plastics. Silicone rubbers also introduce some interesting and useful properties (such as flexibility) of their own. We report here the fabrication of solid organic scintillators loaded with as much as 2% gadolinium, and more than 5% boron. A gadolinium-containing compound, soluble in vinyl toluene monomer and not inhibiting polymerization, was found. The same compound was also found to be soluble in phenyl-substituted silicone fluids that subsequently could be polymerized. In addition, a class of boron compounds also soluble in silicone fluids and not inhibiting polymerization was found. In the absence of phosphors, the resulting boron- and gadolinium-loaded disks were clear and colorless, or only slightly yellow. The disks were compatible with UV-, blue-, blue-green, and green-emitting phosphors and a variety of colors were realized. In addition, it was found in the case of gadolinium loading, the discrete spectrum due to atomic x-rays and conversion was observable if the scintillator sample was small.