Ponente
Descripción
The exploration of nuclear triaxiality—where a nucleus exhibits three unequal principal axes—provides profound insights into the structural dynamics of atomic nuclei. Recent theoretical advancements have highlighted the prevalence of triaxial shapes in heavy nuclei, including isotopes located in the middle of the shell that were previously believed to be perfectly axially symmetric. The Monte Carlo Shell Model (MCSM) predicts a high prevalence of triaxial deformation in this region through large-scale shell model calculations using effective interactions [1, 2]. The proxy-SU(3) and pseudo-SU(3) models, two algebraic approaches, also support the existence of triaxiality in the rare-earth region [3–5]. Additionally, the Triaxial Projected Shell Model (TPSM) or the Quasiparticle Random-Phase Approximation (QRPA) [6] further strengthens the case for triaxial deformation by predicting unique gamma-band structures characteristic of such nuclei [7].
To empirically validate these theoretical predictions, we propose an experimental investigation of the triaxial nature of 170Dy, a nucleus located precisely at the center of the Z = 50–82 and N = 82–126 major shells. This isotope will be studied in a decay spectroscopy experiment with the new array of high-purity germanium detectors under development at RIBF. The high efficiency of this setup offers unique capabilities for precise gamma-ray spectroscopy, essential for resolving complex decay schemes and extracting accurate spectroscopic information. Our investigation will focus on detecting and analyzing gamma-ray emissions following the decay of the Jπ = 6+ isomer of 170Dy and of the beta decay of 170Tb to 170Dy, for which very limited information currently exists [8]. By constructing detailed level schemes and measuring key observables, such as energy spacings and branching ratios, we aim to identify signatures indicative of triaxial deformation. These new data will be instrumental in benchmarking and refining theoretical models, thereby enhancing our understanding of nuclear shape coexistence and the underlying mechanisms driving triaxiality in this region.
References
[1] T. Otsuka, Physics 4, 258 (2022)
[2] T. Otsuka, arXiv:2303.11299v7 [nucl-th]. (2023)
[3] D. Bonatsos, A. Martinou, S.K. Peroulis, D. Petrellis, P. Vasileiou, T.J. Mertzimekis, N. Minkov, Journal of Physics G: Nuclear and Particle Physics 52, 015102 (2024)
[4] D. Bonatsos, A. Martinou, S.K. Peroulis, D. Petrellis, P. Vasileiou, T.J. Mertzimekis, N. Minkov, Symmetry 16 (2024)
[5] C.E. Vargas, V. Velázquez, S. Lerma-Hernández, N. Bagatella-Flores, The European Physical Journal A 53 (2017)
[6] H. Watanabe, G. Zhang, K. Yoshida, P. Walker, J. Liu, J. Wu, P. Regan, P.A. Söderström, H. Kanaoka, Z. Korkulu et al., Physics Letters B 760, 641 (2016)
[7] S. Jehangir, G.H. Bhat, J.A. Sheikh, S. Frauendorf, W. Li, R. Palit, N. Rather, The European Physical Journal A 57, 308 (2021)
[8] P.A. Söderström, P. Walker, J. Wu, H. Liu, P. Regan, H. Watanabe, P. Doornenbal, Z. Korkulu, P. Lee, J. Liu et al., Physics Letters B 762, 404 (2016)
