New yrast and non-yrast states in I136 and medium-spin structure of I136 and

R. Lozeva

¹

,

E. A. Stefanova

²

,

H. Naïdja

³

et al.

Abstract

In this article we report on the observation of new yrast and non-yrast states in 136 I, populated in the prompt-γ spectroscopy EXILL campaign at the ILL using both 235 U(n,f) and 241 Pu(n,f) reactions. We propose an extension of the level scheme and interpretation of the new spectroscopic results in comparison to state-of-the-art shell-model calculations. We discuss the role of the proton d 5/2 orbital in the structure of this nucleus with Z=53 and the energy split between the πd 5/2 −πg 7/2 orbitals. We also provide a complete overview of all experimental information about this nucleus and include new data from 252 Cf, 248 Cm fission and β-decay of 136 Te to 136 I. We give a new interpretation of 136 I and its decay to 136 Xe in terms of the influence of the neutron h 9/2 orbital and the Gamow-Teller strength for N =83.

Evolution of proton single-particle states in neutron-rich Sb isotopes beyond N=82

“…Here, in the spirit of Zuker [43], the applied two-body monopole corrections mimic the effects of three-body forces, which are missing in the initial realistic interaction. In the past, the N3LOP effective interaction was shown to provide a very good overall description of the spectroscopic properties of a large number of nuclei in the quadrant northeast of 132 Sn, revealing the presence of large quadrupole collectivity in the N = 86, 88 isotones [44][45][46][47][48].…”

“…This feature was already discussed in Refs. [47][48][49]. In the first, the effective SPE were calculated, showing a decrease of the proton gap with increasing neutron number with the inversion taking place at N = 90.…”

Beyond 132Sn: Examples of new data on exotic neutron-rich Te isotopes from fission and β-decay

“…This, respectively, provides a field for more detailed comparison to shell-model, particularly on the strength of the first-forbidden transitions beyond 132 Sn. New ingredients in understanding the role of first-forbidden transitions with respect to the Gamow-Teller strength can now be analysed in details, especially as it is open in 136 I [8], but not seen in the Te chain [14]. Thus, combining both data sets with our previous knowledge in the region, new transitions, new excitation energies and extension of the level schemes, with new spin/parity etc.…”

“…The knowledge of experimental nuclear ingredients is especially interesting beyond 132 Sn as little is known on how the excitation modes develop with the addition of both protons and neutrons for the Sb, Te, I nuclei. Therefore, systematic prompt and decay studies can be such a sensitive probe for their structure [8,9]. Aiming at more global picture and understanding this barely explored neutronrich portion of the nuclear chart, we have performed several investigations, recently.…”

“…We have produced the nuclei of interest following fission such as relativistic 238 U on 9 Be in inverse kinematics, thermal neutron-induced fission on 241 Pu and 235 U or fast neutron-induced fission on 238 U and 232 Th and in β-decay of fission products in several recent γ-ray spectroscopy projects [8][9][10]. Consistent data analysis allows to access various spins and excitation energies and to provide complementary data, better understanding, as well as a new and indispensable input to theory.…”