|
AGATA Collaboration(Cederwall, B. et al), Gadea, A., Jurado, M., Domingo-Pardo, C., Huyuk, T., & Perez-Vidal, R. M. (2020). Isospin Properties of Nuclear Pair Correlations from the Level Structure of the Self-Conjugate Nucleus Ru-88. Phys. Rev. Lett., 124(6), 062501–6pp.
Abstract: The low-lying energy spectrum of the extremely neutron-deficient self-conjugate (N = Z) nuclide Ru-88(44)44 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 Ru-88 were populated via the Fe-54(Ar-36, 2n gamma)Ru-88* fusion-evaporation reaction at the Grand Accelerateur National d'Ions Lourds (GANIL) accelerator complex. The observed gamma-ray cascade is assigned to Ru-88 using clean prompt gamma-gamma-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 N > Z nuclides. The direct observation of such a “delayed” rotational alignment in a deformed N = Z nucleus is in agreement with theoretical predictions related to the presence of strong isoscalar neutron-proton pair correlations.
|
|
|
Perez-Vidal, R. M. et al, Gadea, A., Jurado, M., Domingo-Pardo, C., & Huyuk, T. (2022). Evidence of Partial Seniority Conservation in the pi g9/2 Shell for the N=50 Isotones. Phys. Rev. Lett., 129(11), 112501–7pp.
Abstract: The reduced transition probabilities for the 4+1 -2+1 and 2+1 -0+1 transitions in 92Mo and 94Ru and for the 4+1 -2+1 and 6+1 -4+1 transitions in 90Zr have been determined in this experiment making use of a multinucleon transfer reaction. These results have been interpreted on the basis of realistic shell-model calculations in the f5=2, p3=2, p1=2, and g9=2 proton valence space. Only the combination of extensive lifetime information and large scale shell-model calculations allowed the extent of the seniority conservation in the N = 50 g9=2 orbital to be understood. The conclusion is that seniority is largely conserved in the first 71g9=2 orbital.
|
|
|
Wimmer, K. et al: H., T. (2023). Isospin symmetry in the T=1, A=62 triplet. Phys. Lett. B, 847, 138249–7pp.
Abstract: Excited states in the Tz = 0, -1 nuclei Ga-62 and Ge-62 were populated in direct reactions of relativistic radioactive ion beams at the RIBF. Coincident gamma rays were measured with the DALI2(+) array and uniquely assigned to the A = 62 isobars. In addition, Ge-62 was also studied independently at JYFL-ACCLAB using the Mg-24(Ca-40,2n)Ge-62 fusion-evaporation reaction. The first excited T = 1, J(pi) = 2(+) states in Ga-62 and Ge-62 were identified at 979(1) and 965(1) keV, respectively, resolving discrepant interpretations in the literature. States beyond the first 2+ state in Ge-62 were also identified for the first time in the present work. The results are compared with shell-model calculations in the f p. model space. Mirror and triplet energy differences are analyzed in terms of individual charge-symmetry and charge-independence breaking contributions. The MED results confirm the shrinkage of the p-orbits' radii when they are occupied by at least one nucleon on average.
|
|