Near-Yrast Structures in Odd-Odd ¹²² I Nucleus

Abstract

Excited states of the odd-odd nucleus 122 I are investigated via the fusion-evaporation reaction 116 Cd( 11 B,5n) at a beam energy of 68 MeV. The two most strongly populated bands in 122 I are observed up to excitation energies around 10.5 MeV. Their possible configurations at lower spins are assigned to 𝜋ℎ 11/2 ⊗ 𝜈ℎ 11/2 and 𝜋ℎ 11/2 ⊗ 𝜈𝑑 5/2 based on the observed population, B(M1)/B(E2) values, alignments and signature splitting. E1 transitions are observed connecting the 𝜋ℎ 11/2 ⊗ 𝜈𝑑 5/2 band to the 𝜋ℎ 11/2 ⊗ 𝜈ℎ 11/2 band, which may be evidence of octupole collectivity. Band terminations caused by the full alignment of the valence nucleons outside the 114 Sn core are observed in both bands.

Proton-neutron multiplet states and isomers in the odd-odd nucleus I122

“…Some partial results from the current experiment were reported earlier [9][10][11]. After our reports, a similar experimental result for this nucleus was presented by another group [12,13].…”

“…4, were assigned to be negative parity based on a 9 − band head. Our result was confirmed by a later work [12,13]. Furthermore, the low-lying structures on which collective states are based were not defined until our work.…”

“…This favored state is known to be formed by six valence nucleon alignments, π (h 11/2 ) 3 ν( f 7/2 ) 1 (h 9/2 ) 1 (i 13/2 ) 1 , outside a semi-double-shell closure with Z = 64 and N = 82, 146 Gd. Here, three protons in the h 11/2 orbital produce the maximal spins J p = 27/2 − (11/2 + 9/2 + 7/2) while three neutrons in the f 7/2 , h 9/2 , i 13 space produce J n = 27/2 + (7/2 + 9/2 + 11/2). Notice that among three neutrons in the i 13/2 orbital, two neutrons are under the pairing condition with J = 0.…”

High-Spin Level Scheme of 120 I

“…[8,9] However, the later study by Moon et al [11,12] assigned it to the 𝜋ℎ 11/2 ⊗ 𝜈ℎ 11/2 configuration. Similar controversial assignment also exists in other odd-odd iodine nuclei [11] including 122 I, for which our conclusion [7] agrees with that of Moon et al Likewise, for the present case of 120 I, the 𝜋ℎ 11/2 ⊗ 𝜈ℎ 11/2 configuration assignment is again considered to be reasonable. Band I1 was reported by Kaur et al [8,9] up to the state de-excited by the 506 keV transition shown in Fig.…”

“…Angular correlations of the 𝛾rays were then evaluated by using the ADO methodology as used in Ref. [7].…”