Band Structure in 21Ne

Abstract

The ¹⁸O(α,nγ) reaction at α-particle bombarding energies of 5.2 and 6.1 MeV was used to study the levels in ²¹Ne below 4 MeV excitation. A combination of γ-ray angular distribution and linear polarization measurements using a single crystal Ge(Li) polarimeter confirmed the spins and parities of the 1747 and 2867 keV states to be 7/2⁺ and 9/2⁺ respectively and assigned negative parity to the J = 3/2 level at 3663 keV and J = 5/2 level at 3886 keV. The state at 3735 keV was shown to have J^π = 5/2⁺. Values of the multipole mixing ratios of γ rays deexciting these states were found to be consistent with previous measurements. A γ–γ coincidence experiment revealed the existence of a (1.8 ± 0.7)% decay branch of the 3886 keV level to the 2790 keV level. The results are interpreted in terms of the Nilsson model. Evidence for the existence of a K^π = 1/2⁻ band based on a hole in the 1p_1/2 shell is given.