High-Z liquid scintillators containing tin

Abstract Two series of high- Z liquid scintillators have been developed and found to be useful for detection of X-rays and gamma rays in the energy range of about 4–200 keV. One type of solution is composed of pseudocumene (PC) as the solvent, 4,4″-di(5-tridecyl)-p-terphenyl as the scintillating solute, and tetramethyltin as the heavy-atom compound. A second type of solution contains a much faster but lower-yield solute, 4-bromo-4″-(5-hexadecyl)-p-terphenyl; the other components are the same. A tin loading of 22 weight percent in either of these solutions increases its sensitivity to 8 keV X-rays by a factor of 2.5 for a sample thickness of 1 mm. Well-resolved photopeaks were recorded for 122 keV gamma rays from 57 Co using solutions containing 28 and 49 weight percent tin. Several pulse parameters i.e., rise time, decay time, etc., of the radiation from solutions with and without added tin have been measured by exciting the solutions with pulsed electrons from a linac. The decrease in scintillation yield with increased tin loading was found to be proportional to dilution of the PC solvent. Moreover, decay times of the solutions were not affected by addition of tetramethyltin. Therefore, it is concluded that the heavy atoms do not actively quench the fluorescence from these solutions.