Rise-Time Characteristics of Organic Solution Scintillators

A special demountable cathode-ray tube has been designed to produce electron-beam excitation of organic scintillator solutions. Solutions are irradiated through an electron-permeable window. The beam is swept across the window in 0.4 × 10-9 seconds. A 1P28 photomultiplier and traveling-wave oscilloscope are used in recording. About 25,000 mev of excitation energy is delivered per pulse and pulse oscillograms are free of statistical variations. System response time is due almost wholly to photomultiplier transit-time dispersion. A pure Gaussian form is assumed for the response function of the system in analyzing pulse contours. The time resolution of the system is adequate to permit observation of the dependence of pulse rise times on concentration in solutions of p-terphenyl in toluene and anthracene in benzene. The results are in good agreement with the energy-transfer theory proposed by Kallmann and Furst.