On the Systematics of Even-Even Alpha-Emitters

The systematics of even-even alpha-emitters are studied. Empirical relationships are found, of the form logλ=a+b/v, Z constant for values of Z=84, 86, 88, 90, 92, and 94. For these cases, the relationships found represent a more precise empirical correlation of alpha-energy and disintegration constant than does the Geiger-Nuttall rule. Relationships of the formlogλ=A+B/v, (A-2Z) constant exist for members of different partial radioactive series and are related to the disintegration schemes of the thorium and uranium families.Values of the nuclear radii and internal potentials are calculated from the rigorous form of the Gamow-Condon-Gurney theory. The radii of "normal" even-even alpha-emitters can be presented byr₀=1.57A1/3×10^-13 cm, while the internal potential, U, can be represented byE-U=0.52 Mev. The latter relationship is an indication of the approximate constancy, for the different nuclei, of the logarithmic derivative of the radial wave function at the boundary of the nucleus.The empirical relations logλ=a+b/v,Z constant, are compared with theory; and the significance of the comparison is discussed.The values of the half-lives of Th²²⁴, Ra²²⁰, and Em²¹⁶ are predicted.The isotopes of polonium and emanation, which show departures from "normal behavior," are considered.