Spin and parity determination of the 3.004-MeV level in Al-27: Its low-lying multiplet structure

The spin and parity of the 3.004-MeV level in 27Al have been determined by measuring the angular correlation function of radiation emitted from levels populated by resonant absorption of polarized photons. The nuclear resonance fluorescence experiments were carried out at the High Intensity g-ray Source (HIgS) facility at Duke University using quasi-monoenergetic linearly polarized photon beams. The spin and parity of levels in 27Al were deduced from a comparison of the measured angular distribution ratios and azimuthal intensity asymmetries with theoretical predictions. The observed resonance properties were compared with shell model calculations using the universal sd interaction. The Monte Carlo shell model calculations were also performed to investigate low-energy structure of 27Al