Speaker
Description
The existence of two-γ-phonon excited states in rare-earth nuclei remains a contentious issue in nuclear structure. While examples of single-phonon γ-vibrational states are prevalent in even-even deformed nuclei, identifying two-phonon excitations is challenging due to strength fragmentation and competing non-collective states. Although two-phonon states are predicted by the collective model [1], only six cases have been reported in rare-earth nuclei [2–5]. While these states are largely in agreement with predictions from collective models, their rarity has challenged the validity of a collective model in well-deformed nuclei [6].
Coulomb excitation populates excited states in both beam and target nuclei, while allowing other scattering process to be neglected. The well-established formalism of electromagnetic interactions then allows extraction of reduced matrix elements and branching ratios from experimental γ-ray yields numerically [7].
In this presentation, the results of Coulomb-excitation γ-ray spectroscopy on the rare-earth, even-even nucleus 162Dy with an 16O beam will be presented. Precise measurements of the transition strengths between low-lying (< 2 MeV) excited states of 162Dy were made, building towards a more complete picture of the level scheme and identifying collective features.
References
[1] A. N. Bohr and B. R. Mottelson. Mat -fys Medd 27.16 (1953), pp. 1–174.
[2] A. Aprahamian, S. R. Lesher, et al. Physical Review C 95.2 (2017), p. 024329.
[3] F. Corminboeuf, J. Jolie, et al. Physical Review C 56.3 (1997), R1201–R1205.
[4] C. Fahlander, A. Axelsson, et al. Physics Letters B 388.3 (1996), pp. 475–480.
[5] T. Härtlein, M. Heinebrodt, et al. The European Physical Journal A 2.3 (1998), pp. 253–261.
[6] T. Otsuka, Y. Tsunoda, et al. arXiv.org, 2023. url:https://arxiv.org/abs/2303.11299v3
[7] D Cline. Annual Review of Nuclear and Particle Science 36.1 (1986), pp. 683–716.
