Continuum Spectra from the Be9 (He3, α)2He4 Reaction

Alpha particles from the ${\mathrm{Be}}^{9}({\mathrm{He}}^{3}, \ensuremath{\alpha})2{\mathrm{He}}^{4}$ reaction were recorded at observation angles from 5 to 140 deg using a broad-range spectrograph. Bombarding energies were 3.00 and 4.00 MeV. The alpha continuum was measured from the reaction threshold up to a corresponding excitation energy of 15.5 MeV in the ${\mathrm{Be}}^{9}({\mathrm{He}}^{3}, \ensuremath{\alpha}){\mathrm{Be}}^{8}$ reaction. The continuum is analyzed in terms of two possible decay modes involving spontaneous three-alpha disintegration of ${\mathrm{C}}^{12*}$ or stepwise two-body decay through states in ${\mathrm{Be}}^{8*}$. When Coulomb barrier effects are taken into account, qualitative agreement with the data is obtained by assuming the reaction proceeds via the three-body process. The low-energy anomaly seen in the reactions ${\mathrm{B}}^{11}(p, \ensuremath{\alpha}){\mathrm{Be}}^{8}$ and ${\mathrm{Be}}^{9}(p, d){\mathrm{Be}}^{8}$ was not observed.