1973 年 42 巻 5 号 p. 466-473
Absolute measurements of the mean lifetime of excited states in gaseous atoms have been reported by many authors using various experimental methods. The present paper deals with life time measurements using correlated photons in cascade. Two photons emitted spon-taneously in the cascade of a three level system are detected separately by two photomultipli-ers (PM) and from the time correlation between output photoelectron pulses of the two PM's, the direct measurement of the lifetime of the intermediate state in the cascade transition has been obtained.
The optimum operational condition of this method is discussed quantitatively by analyz-ing the signal-to-noise ratio and the contrast factor which is defined as a ratio of signal to back ground. Based on the analysis, measurements were made on 63P1 level in Hg I, and 2p8 and 2p9. (Paschen notation) levels in Ne I. The measured results on lifetimes and Ne-Ne collisional cross sections are presented in comparison with corresponding results of other wor-kers using different techniques.