Scattering ofHe3fromHe4

Abstract

Doubly charged ${\mathrm{He}}^3$ ions have been scattered from helium gas to permit the investigation of excited states in ${\mathrm{Be}}^7$ at excitation energies between 3.9 and 8.4 MeV. In addition to the known $\frac{7}{2^{-}}$ level at 4.54 MeV, the $\frac{5}{2^{-}}$ member of this $l=3\mathrm{}$ spin-orbit doublet has also been observed. This new state is located at an excitation energy of 6.51±0.04 MeV and has a reduced width of 3.96×${10}^{-13\mathrm{}}$ MeV cm. No positive-parity states are observed in this range of excitation energies. A phase-shift analysis of the data has been made for bombarding energies above 5.75 MeV, and the spin polarization of the scattered particles has been calculated. Several regions in the ${\theta }_{\mathrm{c}.\mathrm{m}.\mathrm{}}$, $E_{{\mathrm{He}}^3}$ plane were found that should yield polarizations near unity.