A positron lifetime spectrometer with improved linearity and resolution

A fast channel of a positron lifetime spectrometer is introduced. It consists of constant fraction discriminators and a time-to-amplitude converter. The integral and differential nonlinearity of the spectrometer are < +- 0.1% and < +- 2%, respectively, in the linear time range of the spectrometer which is about 30 ns. The time resolution (FWHM) of the system with 60Co source and 30% energy channel windows by using C31024 photomultipliers and cylindrical 25 mm x 25 mm NE111 scintillators and 50 mm x 50 mm Pilot U scintillators is 170 ps and 230 ps, respectively. The constructed fast channel is located in one double wide NIM-standard module. (Auth.)