Nuclear Data Sheets for A=227

作者：Rondev Filip; McCutchan Elizabeth; Singh Balraj^*; Tuli Jagdish

来源：Nuclear Data Sheets, 2016, 132: 257-354.

DOI：10.1016/j.nds.2016.01.002

The evaluated spectroscopic data are presented for ten known nuclides of mass 227 (Po, At, Rn, Fr, Ra, Ac, Th, Pa, U, Np). For Po-227, At-227, Rn-227, Pa-227, U-227 and Np-227 nuclei, only the ground-state information is available. Their decay characteristics are mostly unknown. Levels in Fr-227 are known only from the decay of Rn-227 to Fr-227. This decay scheme at present cannot be normalized to deduce gamma intensities per 100 decays due to lack of knowledge about multipolarities of many low-energy transitions. The levels in Ra-227, Ac-227 and Th-227 are known from several decays and reactions, including particle-transfer data for Ra-227 and Ac-227. The decay scheme of Ra-227 to Ac-227 was last studied in 1971 using small Ge detectors. Improved gamma-ray intensity data need to be obtained with a better gamma-detection system. The datasets for Ac-227 have undergone extensive revisions, including detailed data for Pa-231 alpha decay from 1986BaYK report, and single-proton transfer data from 1986MaYU thesis. High-spin (J>13/2 or so) structures are known only for Th-227. Level lifetime data are quite scarce for all the nuclides in this mass chain, thus limiting the knowledge of reduced transition probabilities.
Band structures for Fr-227, Ra-227, Ac-227 and Th-227 are known in detail, together with evidence of weak octupole deformation and consequent parity-doublet structures.

• 出版日期2016-2