Investigation of Excited States inBe8by Alpha-Particle Scattering from He

Abstract

Partial phase shifts have been deduced from the data on the scattering of $\ensuremath{\alpha}$ particles (12.3 to 22.9 Mev) from He, reported in an earlier publication. The interpretation of the phase shifts is as follows: The monotonic decrease of the $S$-wave phase shift throughout the energy range investigated indicates no broad $S$ states in ${\mathrm{Be}}^{8}$ for excitations between 0.5 and 11.45 Mev. The $D$-wave phase-shift energy dependence clearly indicates the 2.9-Mev ${2}^{+}$ state in ${\mathrm{Be}}^{8}$. The $G$-wave phase shift shows a broad ${4}^{+}$ state in the neighborhood of 11 Mev with a reduced width of about 2 Mev. The $I$-wave phase shift is first observed at 20 Mev and is positive.Moderate success has been achieved in explaining the scattering results in terms of Haefner's alphaparticle model of ${\mathrm{Be}}^{8}$.