Abstract
The performances are compared of similar large volumes (20 in.×10 in.×6 in.) of (1) a plastic scintillator (NE 101), (2) a conventional liquid scintillator (PPO plus POPOP in toluene), and (3) a lead-loaded liquid scintillator (NE 314). A description is given of the aluminium-casting oval test unit in which scintillations are viewed by two 5 in. diameter photomultipliers, the output pulses from which are amplified and fed into a Sunvic multichannel analyser. Examples are shown of spectra obtained for each of the scintillators. In the comparison of resolution properties, the plastic scintillator is shown to be slightly superior to the conventional liquid and much superior to the lead-loaded liquid scintillator which failed to show Compton or photo peaks. Consideration is given to the application of a single plastic scintillator unit to the measurement of γ-radiation from the human body, and it is shown that the counting statistics of a 15 minute determination of body potassium, in the presence of 137Cs contamination, give a standard error of only ±2%.