Seminarium Fizyki Jądra Atomowego

Calcium nuclei (Z=20) between doubly closed shells, i.e. N=20 and N=28, offer a unique opportunity to investigate the evolution of nuclear structure from symmetric to neutron-rich systems. Along this isotopic chain, spherical configurations at shell closures are expected to be overcome by deformed structures in mid-shell nuclei, already at low excitation energy. This will significantly affect the interplay between single-particle and collective excitations, as well as particle/hole-core coupling schemes which appear in odd-mass isotopes. Ca nuclei lie in a region where different models can be applied: ab initio approaches [1], shell-model calculations [2], DFT’s [3] and beyond-mean-field models [4-5]. We present recent results on the low-spin structure of 41,42,45,47,49Ca nuclei, populated in a series of (n,), neutron-capture experiments performed at Institut Laue-Langevin in Grenoble using the high-efficiency EXILL [6-7] and FIPPS [8] HPGe arrays. Level schemes were substantially extended and -ray angular correlations were performed in order to pin down spin-parity assignments of the observed states. Experimental results are discussed and compared with theoretical models including the Hybrid Configuration Mixing model developed by the Milano group to microscopically describe particle/hole-core coupled states[7]. Finally, the complementarity of different experimental approaches to investigate the structure of Ca isotopes will be highlighted and neutron-capture reactions will be discussed along with multi-nucleon transfer [9] and Coulomb excitation experiments [10] performed at Laboratori Nazionali di Legnaro.

[1] J. D. Holt et al., Phys. Rev. C 90, 024312 (2014).
[2] Y. Utsuno et al., Progr. Theor. Phys. Suppl. 196, 304 (2012).
[3] M. Bender et al., Rev. Mod. Phys. 75, 121 (2003).
[4] G. Colò et al., Phys. Rev. C 95 (2017) 034303.
[5] S. Bottoni et al., in preparation.
[6] M. Jentschel et al., J. Instrum. 12, 11003 (2017).
[7] S. Bottoni et al., Phys. Rev. C 103, 014320 (2020).
[8] C. Michelagnoli et al., EPJ Web of Conf. 193 04009 (2018).
[9] D. Montanari et al., Phys. Lett. B 697, 288 (2011).
[10] K. Hadyńska et al., Phys. Rev. Lett. 117, 062501 (2016).

kontakt: urban@fuw.edu.pl