Study of the beta-delayed alpha-particle emission ofN16

Abstract

The beta-delayed alpha-particle emission of $^{16}\mathrm{N}$ has been studied, with $^{16}\mathrm{N}$ nuclei produced using 80 MeV/nucleon $^{18}\mathrm{O}$ beams on $^{9}\mathrm{Be}$ targets. The $^{16}\mathrm{N}$ secondary nuclei were mass analyzed and separated from the reaction products using the Michigan State University A1200 isotope separator. A detector array, including four thin surface barrier detectors, a p-i-n diode, a Ge gamma-ray detector, and a two-dimensional position sensitive parallel plate avalanche counter, was used for implantation and study of the separated nuclei. A beta-decay branching ratio of (1.3\ifmmode\pm\else\textpm\fi{}0.3)\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}5}$ to the ${1}^{\mathrm{\ensuremath{-}}}$ state at 9.6 MeV and a centroid of 2.35\ifmmode\pm\else\textpm\fi{}0.05 MeV for the beta-delayed alpha-particle emission were measured. These results are essential for the analysis of a high sensitivity measurement at Yale University of the low-energy beta-delayed alpha-particle emission of $^{16}\mathrm{N}$, and for understanding the $^{12}\mathrm{C}$(\ensuremath{\alpha},\ensuremath{\gamma}${)}^{16}$O reaction in the helium burning process in massive stars.