New approach to spin assignments of intermediate structures in 12C(16O,12C

Abstract

Magnetic substate populations for the ${2}^{+}$ state at 4.44 MeV in $^{12}\mathrm{C}$ were measured in resonant $^{12}\mathrm{C}$${+}^{16}$O inelastic scattering by the \ensuremath{\gamma}-ray recoil method. The m-substate population has been determined in the coordinate frame where a quantization axis is taken along the center of mass scattering angle of a reaction product. This coordinate frame gives an advantage that a resonance spin J can be obtained directly from m-substate angular distributions compared with the beam-axis frame. In addition a decay L value is sensitive to the relative intensity between each m-substate cross section. Our data suggest a spin assignment of ${\mathit{J}}^{\mathrm{\ensuremath{\pi}}}$=${16}^{+}$ or ${17}^{\mathrm{\ensuremath{-}}}$ for the structures at ${\mathit{E}}_{\mathrm{c}.\mathrm{m}.}$=29.8 MeV and 31.8 MeV. Both structures are determined to decay dominantly through the aligned configuration of L=J-2.