Lifetimes of excited nuclear levels.

Reprint: Canadian Journal of Physics, 37, 1036 (1959), Rotational States of Even-Even NucleiReprint: Nuclear Instruments and Methods, Volume 9, No.2 (1960), Methods of Evaluating Delayed Coincidence ExperimentsA new method of analysis of delayed coincidence experiments, the third moment method, is reported. A description of electronic and experimental techniques used to obtain beat time resolution is given; the resolution obtained was 2.33 X 10^-10 s. A number of measurements of mean lives of excited states is given; the values obtained were: 80 keV level in I131, (7 .15 +/- 0.30) X 10^-10 s; 3.2 meV level in Pb208, (4.41 +/- 0.20) X 10^-10 s; 2.62 meV level in Pb208, (4.7 +/-1.5) X 10^-11 s; 323 keV level in V51, (2.5 +/- 0.6) x 10^-10 s; 374 keV level in Ca53, less than 8 X 10^-11 s; 993 keV level in Ca43, (1.3+0.2/-0.4) X 10^-10 s; 288 keV level in Gd156, (2.08+/- 0.20) The expected mean lives of the second excited states in the even-even rare earths and heavy nuclei are calculated using the rotational model; these are compared with known experimental results, and future work in the rare earths is proposed