Heavy Elements in Plastic Scintillators

The objective of this work is to study the possibilities of incorporating into plastic scintillators substantial quantities of heavy element compounds without the introduction of appreciable color or haze. Factors governing the quenching of the light output are considered, and a practical balance is struck between lowered pulse height and the quantity of heavy element introduced. The various components required in a heavy-element-loaded plastic scintillator are outlined, with a discussion of the effects of variations in their chemical character and proportion. Specific approaches to the problem are outlined as follows: 1) the inclusion in the plastic scintillator of organo-metallic compounds, 2) inclusion of essentially non-ionic metal salts, 3) inclusion of chelated metal compounds, 4) use of a base plastic material in which a variety of metal compounds are more soluble than in the standard vinyl-aromatic type of base plastic, and 5) inclusion of a metal compound that is also a monomer. Possible applications to detection of low energy radiation and of thermal neutrons are discussed.