Orateur
Description
For several decades, stable even-mass Cd isotopes have been considered to be textbook examples of multiphonon spherical vibrators [1] based on the excitation energy pattern of their low-lying states. However, a detailed study of $^{110}$In $\beta$ decay and subsequent beyond-mean-field theoretical calculations [2-5] suggested instead the presence of multiple shape coexistence in $^{110}$Cd and $^{112}$Cd isotopes. To verify this hypothesis complete sets of transitional and diagonal E2 matrix elements, including their relative signs, are needed. This key experimental information can be obtained by applying the low-energy Coulomb-excitation technique [6].
Coulomb excitation of $^{110}$Cd using a 187-MeV $^{60}$Ni beam was performed at National Institute for Nuclear Physics - Legnaro National Laboratories, Italy [7]. This experiment was a part of a broader program focused on systematic Coulomb-excitation studies of $^{110}$Cd initiated at Heavy Ion Laboratory, University of Warsaw, with light beams of $^{32}$S [5] and $^{14}$N ions [8]. The $^{60}$Ni + $^{110}$Cd experiment was carried out using 11 AGATA triple clusters [9,10] and the particle detection array SPIDER [11] to register back-scattered beam ions. SPIDER was placed at laboratory angles ranging from 128 to 160 degrees to enhance the probability of multistep Coulomb excitation. In total 20 states of both negative and positive parity were populated up to 3 MeV of excitation energy, including in particular the $0^+_3$ state at 1731 keV.
Details of the experiment performed with AGATA at LNL and chosen aspects of the on-going data analysis will be presented along with the preliminary results obtained.
References
[1] R.F. Casten, Nuclear Structure from a Simple Perspective (Oxford Univ. Press 1990)
[2] P.E. Garrett et al., Phys. Rev. C 86 (2012) 044304.
[3] P.E. Garrett et al., Phys. Rev. C 101 (2020) 044302.
[4] P.E. Garrett et al., Phys. Rev. Lett. 123 (2019) 142502.
[5] K. Wrzosek-Lipska et al., Acta Phys. Pol. B51 (2020) 789.
[6] M. Zielińska, Low-Energy Coulomb Excitation and Nuclear Deformation, in: The Euroschool on Exotic Beams, vol.VI, S.M. Lenzi and D.Cortina-Gil (eds.) Lecture Notes in Physics 1005, pp. 43-86 (Springer, 2022)
[7] K. Wrzosek-Lipska et al., INFN-LNL-273 (2023), 24.
[8] I. Piętka, MSc. thesis, Unversity of Warsaw, Poland (2023)
[9] S. Akkoyun et al., Nucl. Instrum. Methods A668 (2012) 26.
[10] J.J. Valiente-Dobón et al., Nucl. Instrum. Methods A1049 (2023) 168040.
[11] M. Rocchini et al., Nucl. Instrum. Methods A971 (2020) 164030.
