Abstract
The low-lying energy spectrum of the extremely neutron-deficient self-conjugate () nuclide has been measured using the combination of the Advanced Gamma Tracking Array (AGATA) spectrometer, the NEDA and Neutron Wall neutron detector arrays, and the DIAMANT charged particle detector array. Excited states in were populated via the fusion-evaporation reaction at the Grand Accélérateur National d’Ions Lourds (GANIL) accelerator complex. The observed -ray cascade is assigned to using clean prompt -2-neutron coincidences in anticoincidence with the detection of charged particles, confirming and extending the previously assigned sequence of low-lying excited states. It is consistent with a moderately deformed rotating system exhibiting a band crossing at a rotational frequency that is significantly higher than standard theoretical predictions with isovector pairing, as well as observations in neighboring nuclides. The direct observation of such a “delayed” rotational alignment in a deformed nucleus is in agreement with theoretical predictions related to the presence of strong isoscalar neutron-proton pair correlations.
- Received 11 July 2019
- Revised 27 August 2019
- Accepted 18 December 2019
DOI:https://doi.org/10.1103/PhysRevLett.124.062501
Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.
Published by the American Physical Society