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

静間 俊行*; Omer, M.  ; 羽島 良一*; 清水 則孝*; 宇都野 穣   

Shizuma, Toshiyuki*; Omer, M.; Hajima, Ryoichi*; Shimizu, Noritaka*; Utsuno, Yutaka

Nuclear resonance fluorescence (NRF) is a promising technique for the nondestructive assay (NDA) of nuclear materials. One of the features of the NRF is the angular distribution of the emitted photons in response to a linearly polarized incident beam. Here we irradiate the calibration standard of Al to linearly polarized beam. The spin and parity of the 3.004-MeV level in Al 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 -ray Source (HIS) facility at Duke University using quasi-monoenergetic linearly polarized photon beams. The spin and parity of levels in Al 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 Al. This work was supported by the subsidiary for promotion of strengthening nuclear security or the like of the Ministry of Education, Culture, Sports, Science, and Technology (MEXT), Japan.