Collective and noncollective states in120Te

Abstract

High-spin states in 120 Te were populated in the reaction 80 Se( 48 Ca, α4n) 120 Te at a beam energy of 207 MeV and γ-ray coincidences were measured using the Gammasphere spectrometer. The previously known level scheme is extended to higher spin and new interband transitions and sidefeeding branches are established. Five highly-deformed rotational bands, extending up to almost I = 50, are observed for the first time. The bands are compared with similar structures found recently in neighboring nuclei. The experimental results are interpreted within the framework of the cranked Nilsson-Strutinsky model. Configuration assignments to several terminating states and to the high-spin bands are discussed.

High-spin rotational bands in123I

“…Studies of neighboring nuclei [6][7][8][9][10] as well as the present calculations for 123 I, see below, indicate that the high-spin bands in the A 125 region are built on configurations with two proton holes in the g 9/2 subshell. Representative potential energy surfaces (PES) for such configurations with parity and signature (π, α) = (+, 1/2) are displayed in Fig.…”

“…3. A comparison with the high-spin bands in the neighboring nuclei 120 Te [7], 125 I [8], and 125 Xe [9] demonstrates the similarity of their behavior. At high frequencies, abovehω = 0.95 MeV, the slopes of the curves for the 123 I bands change, however, not as drastically as for band L4 in 125 Xe.…”

“…Gamma-ray coincidence events were recorded with the Gammasphere spectrometer [11]. Further details on the experiment and the data analysis are given in previous publications by the present collaboration [2,7].The three rotational sequences with large moments of inertia discovered in 123 I are displayed in Fig. 1.…”

“…The shape change is induced by the successive alignment of nucleons along the rotation axis and, finally, the level sequences terminate in maximally aligned oblate states [1][2][3][4][5][6]. In addition, several high-spin rotational bands have recently been observed in 120 Te [7], 124 Ba [6], 125 I [8], 125 Xe [9], and 126 Xe [10], which extend far beyond the noncollective oblate states. Only some of these sequences are firmly connected to lower-lying levels; they feed normal-deformed states in the spin range of I 25 at excitation energies around 10 MeV.…”

Effective field theory for nuclear vibrations with quantified uncertainties

“…122 Te exhibits a non-vibrational state already at the three-phonon level. The breakdown of the collective behavior is a consequence of competing single- particle motion, know to exist in tellurium isotopes [75][76][77][78][79][80], and signaled in 122 Te by the unusual energy ratios E(4 + 1 )/E(2 + 1 ) < 2 and E(6 + 1 )/E(4 + 1 ) < 1.5 [81]. The alignment of both valence nucleons and protons promoted across the Z = 50 shell gap breaks the spherical symmetry and give rise to non-collective deformed states.…”