[en] A method is described for the determination of the decay times of scintillating fibers subjected to ionizing radiation. Excitation is by beta radiation from a custom-made ⁹⁰Sr/⁹⁰Y source. Pulse shapes are determined using time correlated single photon counting (TCPC) techniques

[en] New long-wavelength-emitting, high-speed, liquid scintillators have been developed and tailored specifically for plasma diagnostic experiments employing fiber optics. These scintillators offer significant advantages over commercially available plastic scintillators in terms of sensitivity and bandwidth. FWHM response times as fast as 350 ps have been measured. Emission spectra, time response data, and relative sensitivity information are presented

[en] New long-wavelength-emitting, high-speed, liquid scintillators have been developed and tailored specifically for plasma diagnostic experiments employing fiber optics. These scintillators offer significant advantages over commercially available plastic scintillators in terms of sensitivity and bandwidth. FWHM response times as fast as 350 ps have been measured. Emission spectra, time response data, and relative sensitivity information are presented

[en] Long-wavelength liquid scintillators have been developed for fiber-optic plasma-diagnostic experiments. Relative system sensitivity and bandwidth data as a function of fiber length for several scintillator systems will be presented

[en] The modeling technique described was developed to aid in interpretation of the effects of various changes in scintillator formulations on the shape of scintillation pulses. Theoretical pulse shapes were synthesized, the system response function is folded in, and the result is overlaid on the raw data arrays. It has thus been possible to distinguish relatively unambiguously between quenching of the solvent and the solute when various heavy-atom quenchers were added to solutions of a series of substituted terphenyls. The method is found to be valuable in providing basic information about energy transfer steps in a multicomponent scintillator

[en] Heating organic liquid scintillator solutions has proven to be an efficient way to improve the time response in some cases. Higher temperatures increase the rates of diffusion-controlled energy transfer processes in dilute solutions and in solutions with relatively high viscosity at room temperature. Under these conditions both the excitation rate and the rate of intermolecular quenching, including concentration-quenching, become faster at higher temperatures. Except for specific concentration-quenching effects, little temperature dependence of the scintillator pulse parameters was observed in the more concentrated or in the less viscous systems

[en] A method is described for the determination of the decay times of scintillating fibers subjected to ionizing radiation. Excitation is by beta radiation from a custom-made ⁹⁰Sr/⁹⁰Y source. Pulse shapes are determined using time correlated single photon counting (TCPC) techniques. (Author)

[en] A time-correlated single photon counting system for measuring scintillation decay times is described in which the system time response function has a FWHM less than 220 ps. This is a two-scintillator system in which a time-to-amplitude converter (TAC) is started by gamma-induced flashes from a bright 500-ps FWHM scintillator closely coupled to a 14-stage photomultiplier. The TAC is stopped by single-photon pulses from an amplified high-gain microchannel-plate photomultiplier viewing the sample. A ⁶⁰Co source is sandwiched between the start scintillator and the sample to be measured. The time correlation depends on the coincident excitation of both scintillators by the two γ rays from each nuclear disintegration. (author)

[en] Several liquid scintillator for formulations are described that were developed over the last several years on the Radiation-to-Light Converter program at EG and G Energy Measurements, Inc. The general aim of this program is to develop new scintillators that are needed for monitoring fast pulses of ionizing radiation. A large part of this effort has been directed toward new red scintillators for remote sensing applications, in which the scintillation pulses are to be transmitted to the detectors through long optical fibers. The main absorption band for red dyes is often at too long a wavelength for good overlap with the emission band of excited solvent molecules. In such cases, an intermediate wavelength shifter is used, whose absorption band overlaps well with the solvent emission, and whose emission overlaps the absorption band of the final emitter. With a good intermediate dye, energy transfer to the final emitter will be so fast that little energy is lost by radiation from excited singlets of the intermediate, and the overall time response is usually improved. Pseudo-cumene has been found to be the most efficient solvent for most nonpolar aromatic solutes, which usually emit a fairly short wavelengths, from near-ultraviolet to green light. Benzyl alcohol has been found to be an efficient solvent for most of the polar red-emitting laser dyes

[en] 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 increses 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 ⁵⁷Co 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. (orig.)