Digital positron lifetime spectrometer for measurements of radioactive materials

A digital positron lifetime spectrometer for the measurements of high-level radioactive materials has been constructed and successfully tested. The equipment consists of a digital oscilloscope and three movable scintillation detectors operating in triple-coincidence mode. The time resolution of 188 ps full-width at half-maximum (FWHM) is achieved for the positron lifetime measurements of radioactive specimens. The set-up has been calibrated, optimised and tested by comparison of the results of well-known material with and without high background radiation. This paper reports on the radiological shielding, electronic update, stability and the performance of this new spectrometer that has been installed in the controlled area of the Laboratory for High and Medium level Activity (LHMA) at SCK•CEN.