Abstract
The excitation energy of deformed intruder states (specifically the 2p2h bandhead) as a function of proton number along is of interest both in terms of better understanding the evolution of nuclear structure between spherical and the Island of Inversion nuclei, and for benchmarking theoretical descriptions in this region. At the center of the Island of Inversion, the (where ) neutron excitations across a diminished gap result in deformed and collective ground states, as observed in . In heavier isotones, excitations do not dominate in the ground states but are present in the relatively low-lying level schemes. With the aim of identifying the expected state in , the only isotone for which the neutron 2p2h excitation bandhead has not yet been identified, the reaction has been revisited in inverse kinematics with the HELical Orbit Spectrometer (HELIOS) at the Argonne Tandem Linac Accelerator System (ATLAS). While a candidate state has not been located, an upper limit for the transfer reaction cross section to populate such a configuration within a 2.5 to 3.6 MeV energy range provides a stringent constraint on the wave function compositions in both and .
1 More- Received 30 July 2020
- Accepted 14 October 2020
DOI:https://doi.org/10.1103/PhysRevC.102.064317
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