[en] Progress is reported from efforts to develop radiation-to-light converters suitable for use with optical fibers as they are applied to the diagnostics of transient nuclear phenomena. Liquid and plastic fluors have been prepared which emit in the 550- to 600-nm region. Ternary liquid systems with decay times as short as 1.3 ns at 560 nm and plastic fluors with decay times less than 3 ns at 560 nm are reported. Other liquid and plastic fluors are reported with improved emission characteristics in the region of 600 nm. Conversion efficiences, on a pulse amplitude basis, are generally lower than that of a commercially available 570 nm-16 ns plastic fluor