Observation of High-Lying Levels inBe8fromα−αElastic Scattering

Abstract

The elastic scattering of $\alpha$ particles from ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ has been measured in the energy range between 30 and 70 MeV. A phase-shift analysis was used to investigate the even-spin, positive-parity levels in ${}_{}{}^8{}_{}{}^{}\mathrm{Be}$ in the region between 15 and 35 MeV of excitation. New $0^{+}$ and $4^{+}$ levels have been located near 20.3 and 25.6 MeV, respectively. The positions of five $2^{+}$ levels and an additional $4^{+}$ level are compared with previous work and with theoretical predictions based on the intermediate-coupling shell model.