Vv. Baranov et al., HIGHLY EFFICIENT SPECTROMETER OF DELAYED COINCIDENCES FOR MEASURING POSITRONIUM LIFETIME, Instruments and experimental techniques, 38(1), 1995, pp. 18-22
We have designed and built an automated spectrometer of delayed coinci
dences to study a new phenomenon, namely monofrequent oscillations in
the angular distribution of gamma-quanta due to 3 gamma-decay of posit
ronium in a weak magnetic field. The spectrometer detection unit consi
sts of three NaI(Tl) scintillation detectors 100 mm long and 150 mm in
diameter. The time resolution of the facility is 7 nsec. A magnetic f
ield is generated by permanent samarium-cobalt magnets. A powdered tar
get that generates positronium is placed in a vacuum-tight flask with
a positron source made from Na-22. Experimental results are given and
a data-processing technique which compensates for the differential non
linearity of the time-to-analog converter is proposed.