Phenomenological formula for alpha-decay half-lives

Abstract

A phenomenological formula is presented for the partial half-life from the Q value for α decay. It is constructed in a conventional way by considering the penetrability of a charged particle in a spherical Coulomb potential. Parameters in the formula are fixed because they are determined by physical constants except for the following three adjustable parameters: the product of the collision frequency of an α particle and the formation probability, N; the distance between the charge radius and the radius of an inner point of the Coulomb barrier, r ₀; and the odd-mass hindrance, h ₀. The values obtained for the three adjustable parameters are reasonable, in contrast with those of conventional models such as the Viola–Seaborg formula. The root-mean-square deviations from experimental partial half-lives for even–even, odd-A, and odd–odd nuclei are 0.344, 0.740, and 0.940 (in log₁₀), respectively. The obtained formula gives half-lives that are two or three times longer than those obtained using the Viola–Seaborg formula in the superheavy nuclear mass region.

Keywords:

• alpha-decay
• nuclear structure
• superheavy nuclei
• ENSDF

Acknowledgements

The author thanks Prof. M. Yamada and Dr. S. Chiba for valuable comments. This work was supported in part by a Grant-in-Aid for Young Scientists (B) 19740151 from the Ministry of Education, Culture, Sports, Science and Technology (MEXT) of Japan.