Scattering of ${\mathrm{He}}^3$ from ${\mathrm{He}}^4$ and States in ${\mathrm{Be}}^7$

The range of excitation energies in ${\mathrm{Be}}^7$ from 3.28 to 4.73 Mev has been investigated by Van de Graaffaccelerated ${\mathrm{He}}^{3+}$ ions scattered from ${\mathrm{He}}^4$ gas in a differentially pumped, large-volume scattering chamber. The second excited state in ${\mathrm{Be}}^7$ has been studied, and its laboratory resonant energy and width have been determined to be 5.17 Mev and 0.180 Mev, respectively, corresponding to an excitation energy in ${\mathrm{Be}}^7$ of 4.53±0.02 Mev and a center-of-mass width of 0.102 Mev. The spin and parity are $J={\frac{7}{2}}^{-}$ and the reduced width is 3.0×${10}^{-13\mathrm{}}$ Mev-cm. The behavior of the nonresonant phase shifts is shown to be qualitatively consistent with other known states in ${\mathrm{Be}}^7$, whose resonant energies lie outside the range of the present experiment.