Alpha-Alpha Scattering in the Energy Range 5 to 9 Mev

Abstract

The scattering of alpha particles from helium has been experimentally studied in the energy range 5 to 9 Mev by the measurement of three excitation functions at the center-of-mass angles 30\ifmmode^\circ\else\textdegree\fi{} 33\ensuremath{'}, 54\ifmmode^\circ\else\textdegree\fi{} 44\ensuremath{'}, and 70\ifmmode^\circ\else\textdegree\fi{} 7\ensuremath{'}. A phase-shift analysis has been performed which indicates that only the $S$- and $D$-wave phase shifts are necessary to fit the data in this energy region. Only the well-known $D$ state at approximately 2.9 Mev in ${\mathrm{Be}}^{8}$ was observed. The $D$ state has been compared to the single-level dispersion theory and level parameters have been extracted which are compatible with the alpha-particle model of ${\mathrm{Be}}^{8}$.