Particle decay from the giant resonance region ofCa40

Abstract

The reactions $^{40}\mathrm{Ca}(\ensuremath{\alpha}, 2\ensuremath{\alpha})^{36}\mathrm{Ar}$ and $^{40}\mathrm{Ca}(\ensuremath{\alpha}, \ensuremath{\alpha}p)^{39}\mathrm{K}$ have been studied at 115-MeV bombarding energy in order to obtain the charged particle decay characteristics of the giant quadrupole resonance at ${E}_{x}=18.0$ MeV. Energy and angle were measured for both outgoing light particles to completely define the kinematics. Weak proton decay to the ${d}_{\frac{3}{2}}$ ($\frac{{\ensuremath{\Gamma}}_{{p}_{0}}}{\ensuremath{\Gamma}}={0.08}_{\ensuremath{-}0.03}^{+0.05}$) and ${s}_{\frac{1}{2}}$ ($\frac{{\ensuremath{\Gamma}}_{{p}_{1}}}{\ensuremath{\Gamma}}={0.22}_{\ensuremath{-}0.08}^{+0.05}$) hole states of $^{39}\mathrm{K}$ was observed from the giant quadrupole resonance while most of the decay proceeded to the region of the ${d}_{\frac{5}{2}}$ hole states. While the ($\ensuremath{\alpha}, 2\ensuremath{\alpha}$) reaction populated the $^{36}\mathrm{Ar}$ ground state (${\mathrm{O}}^{+}$), 1.97-MeV state (${2}^{+}$), and 4.18-4.44-MeV states (${4}^{+}$, ${3}^{\ensuremath{-}}$), only upper limits could be established for \ensuremath{\alpha} decay of the giant quadrupole resonance ($\frac{{\ensuremath{\Gamma}}_{{a}_{0}}}{\ensuremath{\Gamma}}<0.06$). Significant decay of the 14-MeV $L=2$ state to the ground state of $^{36}\mathrm{Ar}$ was observed ($\frac{{\ensuremath{\Gamma}}_{{a}_{0}}}{\ensuremath{\Gamma}}\ensuremath{\sim}0.9\ifmmode\pm\else\textpm\fi{}0.2$).NUCLEAR REACTIONS $^{40}\mathrm{Ca}(\ensuremath{\alpha}, \ensuremath{\alpha}p)$, ($\ensuremath{\alpha}, 2\ensuremath{\alpha}$), ${E}_{\ensuremath{\alpha}}=115$ MeV; measured $\frac{{d}^{4}\ensuremath{\sigma}}{d{\ensuremath{\Omega}}_{\ensuremath{\alpha}}d{\ensuremath{\Omega}}_{p}d{E}_{\ensuremath{\alpha}}d{E}_{p}}$,$\frac{{d}^{4}\ensuremath{\sigma}}{d{\ensuremath{\Omega}}_{\ensuremath{\alpha}}d{E}_{\ensuremath{\alpha}}d{E}_{\ensuremath{\alpha}}}$, ($\ensuremath{\alpha}\ensuremath{-}p$) angular correlation giant quadrupole resonance decay; deduced branching ratios, giant quadrupole resonance.