Firm spin and parity assignments for high-lying, low-spin levels in stable Si isotopes

natural silicon target was investigated in a ^nat Si( γ,γ ^' ) photon-scattering experiment with fully linearly-polarised, quasi-monochromatic γ rays in the entrance channel. The mean photon energies used were ⟨E_γ⟩ = 9.33, 9.77, 10.17, 10.55, 10.93, and 11.37 MeV, and the relative energy spread (full width at half maximum) of the incident beam was E_γ/⟨E_γ⟩≈ 3.5–4