High-spin states above the isomers in neutron-rich iodine nuclei near N = 82
Résumé
Excited states of neutron rich Iodine isotopes 130−134 I above the high spin isomers have been identified using prompt-delayed γ-ray spectroscopy. The Iodine isotopes have been produced as fission fragments of fusion-fission and transfer induced fission of 9 Be(238 U, f) at a beam energy of 6.2 MeV/u. The complete (A, Z) identification was obtained using the large acceptance magnetic spectrometer VAMOS++. The AGATA γ-ray tracking array was used to detect the prompt γ rays while the delayed γ rays (in the time range of 100 ns to 200 µs) from the isomeric states were identified by the EXOGAM segmented Clover detectors, placed behind the focal plane of VAMOS++ spectrometer. The high spin states above the (8 −) isomers in 130,132 I have been populated for the first time and a new isomer in 132 I has been identified. New γ-ray transition has also been assigned to the level structure of 134 I. Prompt transitions above the 19/2 − isomer have been identified in 131,133 I, for the first time. The level structures are interpreted in terms of the systematics of odd-Z nuclei above Z = 50 shell closure and large scale shell model calculations.
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