Half-lives and delayed neutron emission probabilities of neutron-rich Li-Al nuclides.

Abstract

Beta-decay half-lives and delayed neutron emission probabilities of very neutron-rich nuclides from Li to Al have been measured by a delayed coincidence technique. Neutron-rich nuclides were produced by reaction of 800-MeV protons on a $^{232}\mathrm{Th}$ target and were individually identified by use of the time-of-flight isochronous spectrometer. For 16 previously measured nucides, the half-lives determined here agree with literature values within the uncertainties. The previously unmeasured half-lives for $^{25}\mathrm{F}$ (59\ifmmode\pm\else\textpm\fi{}40 ms) and $^{28}\mathrm{Ne}$ (14\ifmmode\pm\else\textpm\fi{}10 ms) have been determined. Delayed neutron emission has been measured for $^{12}\mathrm{Be}$, $^{14}\mathrm{B}$, $^{17}\mathrm{C}$, $^{18}\mathrm{N}$, $^{25}\mathrm{F}$, and $^{28}\mathrm{Ne}$. Emission probabilities are reported for 19 precursors and upper limits are reported for 12 other nuclides. These data are compared with predictions of several beta-decay models.