Evidence for a Nuclear Tensor Force from Mass-14 Beta- and Gamma-Ray Data

Abstract

The role of beta- and gamma-ray matrix elements in the determination of wave functions for the ${s}^{4}{p}^{10}$ states of mass 14 is examined. The data considered include the Gamow-Teller (beta) matrix elements of $^{14}\mathrm{C}$ and $^{14}\mathrm{O}$ and the $M1$ and $E2$ matrix elements connecting the lowest four ${s}^{4}{p}^{10}$ states of $^{14}\mathrm{N}$. The magnetic moment of $^{14}\mathrm{N}$ is also discussed. The shell-model wave functions considered arise mainly from the ${s}^{4}{p}^{10}$ configuration but include admixtures of the ${s}^{4}{p}^{8}$ ($2s, 1d$) configuration. It is found that the data, considered as a whole, cannot be explained if the ${s}^{4}{p}^{10}$ components of the wave functions are derived from a central plus spin-orbit interaction only, but that quite satisfactory agreement is obtained if the nuclear force includes a tensor part. The bulk of the cancellation of the $^{14}\mathrm{C}$ beta decay matrix element takes place within the ${s}^{4}{p}^{10}$ configuration. In general, configuration mixing is of secondary importance; its most noticeable effect is on the $M1$ decay of the first-excited state of $^{14}\mathrm{N}$.