Speaker
Description
The well-accepted view of stable cadmium isotopes as excellent examples of spherical vibrational behaviour was put to question following detailed $\beta$-decay and ($n$,$n'\gamma$) spectroscopy [1-3]. A novel interpretation involving multiple shape coexistence was proposed for $^{110,112}$Cd and recently extended to $^{106}$Cd [4]. Supporting evidence for significant ground-state deformation was reported following a "safe" Coulomb-excitation study [5] in line with beyond-mean field (BMF) calculations [4].
This intriguing structural puzzle is addressed in more detail using "unsafe" Coulomb excitation of a $^{106}$Cd beam on a $^{92}$Mo target at beam energies exceeding by 8 to 40% the safe Coulomb excitation energy [6]. The state-of-the-art HPGe $\gamma$-ray tracking array AGATA [7] coupled to the VAMOS++ spectrometer [8] is used to study the balance between the Coulomb and nuclear interactions in the population of twenty excited states in $^{106}$Cd. The effects of Coulomb-nuclear interference on the experimental excitation cross sections are explored using the coupled-channel codes FRESCO [9] and GOSIA [10].
It will be demonstrated that unsafe Coulomb-excitation data can be used to extract valuable spectroscopic information, such as quadrupole and octupole transition strengths, in a model-independent way. Selected results will be presented, including the first measurement of B(E3) values obtained for several negative-parity states, and discussed in terms of a possible quadrupole-octupole coupling scenario. The extracted B(E2) values will be compared to new BMF calculations using the symmetry-conserving configuration mixing method with cranking [11].
[1] P.E. Garrett et al., Phys. Rev. C 75, 054310 (2007).
[2] P.E. Garrett et al., Phys. Rev. Lett. 123, 142502 (2019).
[3] P.E. Garrett et al., Phys. Rev. C 101, 044302 (2020).
[4] M. Siciliano et al., Phys. Rev. C 104 (2021) 034320.
[5] T.J. Gray et al., Phys. Lett. B 834, 137446 (2021).
[6] D. Cline, Annu. Rev. Nucl. Part. Sci. 36, (1986) 683.
[7] S. Akkoyun\textit et al., Nucl. Instrum. Methods Phys. Res. A 668, 26 (2012).
[8] H. Savajols, Nucl. Instrum. Methods Phys. Res. B 204, 146 (2003).
[9] I.J. Thompson, Comput. Phys. Rep. 7, 167 (1988).
[10] T. Czosnyka et al., Bull. Am. Phys. Soc. 28, (1983) 745.
[11] D. Kalaydjieva et al., submitted to EPJ A (EPJA-108684), 2026.
| Contribution category | Experiment |
|---|---|
| Presenter status | Postdoc |