Speaker
Description
Nuclear shape coexistence plays a crucial role in understanding the microscopic origin of nuclear deformation [1-4].
In this respect, the Ca isotopic chain between the shell closures at N=20 and N=28 is an optimal test
area where different theoretical approaches can be used and their predictions compared with experimental data (\textit{e.g.} large-scale Shell Model calculations, Density Functional Theory and \textit{ab-initio} methods [5-7]).\
In this work, we report on high-precision low-spin gamma-ray spectroscopy of even-even $^{42}$Ca and $^{44}$Ca nuclei populated via thermal neutron capture reactions at the Institut Laue-Langevin (ILL).
In both $^{42}$Ca and $^{44}$Ca, the presence of $0^+$ excitations associated with deformed and superdeformed structures has already been demonstrated [8,9], however, further investigation is still essential to study other possible excitations associated with deformed configurations.
This is a complementary study to the existing analysis on the odd systems $^{41,47,49}$Ca [10], already published by this collaboration, and it aims to track the evolution of the nuclear structure along the Calcium isotopic chain.\
$^{42}$Ca and $^{44}$Ca were populated via (n$_{th}$, $\gamma$) reaction on CaCo$_3$ targets, including one enriched with radioactive $^{41}$Ca.
The $\gamma$ cascades depopulating the neutron-capture states, located at 11.5 MeV and 11.1 MeV, respectively, were detected by the HPGe FIPPS array [11].
Employing $\gamma$-$\gamma$ and $\gamma$-$\gamma$-$\gamma$ coincidence techniques, the level schemes of $^{42}$Ca and $^{44}$Ca were significantly expanded by adding 10 and 56 new levels and 109 and 610 new transitions, respectively.
These results will be presented together with preliminary studies on $\gamma$-$\gamma$ angular correlations to establish the spin and parities of excited states.
Comparison with Shell Model calculations will also be discussed.
Bibliography
[1] K. Heyde and J. L. Wood. In: Rev. Mod. Phys. 83 (2011)
[2] P. E. Garrett, M. Zieli´nska, and E. Cl´ement. In: Progress in Particle and Nuclear Physics 124 (2022)
[3] S. Leoni et al. In: Progress in Particle and Nuclear Physics 139 (2024)
[4] S. Leoni et al. In: The European Physical Journal Special Topics 233
(2024)
[5] J. D. Holt et al. In: Phys. Rev. C 90 (2014)
[6] Y. Utsuno et al. In: Progress of Theoretical Physics Supplement 196 (2012)
[7] M. Bender et al. In: Rev. Mod. Phys. 75 (2003)
[8] K. Hady´nska-Klek et al. In: Phys. Rev. Lett. 117 (2016)
[9] C.W. Towsley, D. Cline, and R.N. Horoshko. In: Nuclear Physics A 204 (1973)
[10] S. Bottoni et al. In: Phys. Rev. C 103 (2021)
[11] C. Michelagnoli et al. In: EPJ Web Conf. 193 (2018)