Speaker
Description
A. Di Pietro$^1$, N. Szegedi$^1$, P. Figuera$^1$, S. Cherubini$^{1,2}$,M. La Cognata$^1$, L. Guardo$^1$, M. Gulino$^{1,3}$,L. Lamia$^{1,2}$, A. Oliva$^1$, G. Pizzone$^{1,2}$, G. Rapisarda$^{1,2}$, R. Sparta'$^{1,3}$, M.L. Sergi$^{1,2}$, D. Torresi$^1$, A. Tumino$^{1,2}$, T. Davinson$^4$, N. Duy$^5$, J.P. Fernandez Garcia$^6$, S. Heinitz$^7$, S. Hayakawa$^8$, E.A. Maugeri$^7$, M. Milin$^9$, H. Shimizu$^8$, D. Schumann$^7$, A. Shotter$^4$, N. Soic$^{10}$, H. Yamaguchi$^8$, L. Yang$^8$
1 INFN- Laboratori Nazionali del Sud, Catania, Italy
2 Dipartimento di Fisica ed Astronomia, Università di Catania, Catania, Italy
3 Facoltá di Ingegneria e Architettura, Universitá degli Studi di Enna “Kore”, Enna, Italy
4 School of Physics and Astronomy, University of Edinburgh, Edinburgh, UK
5 Department of Physics, Sungkyunkwan University, Institute of Research and Development, Duy Tan University
6 Departamento de Física Atómica, Molecular y Nuclear, Universidad de Sevilla, Apartado 1065, 41080 Sevilla, Spain
7 Paul Scherrer Institut, Switzerland
8 CNS, University of Tokyo, Wako, Japan
9 University of Zagreb, Zagreb, Croatia
10 Ruđer Bošković Institute, Zagreb, Croatia
Some nuclear properties can be understood by modeling nuclei as loosely interacting clusters. Among the various cluster phenomena observed in light unstable nuclei, particularly neutron-rich ones, is a unique form of clustering where an alpha-cluster structure is held together by neutron exchange, akin to covalent bonding in molecules. In the case of neutron-rich nuclei, theoretical predictions by Suhara and Kanada-En'yo [1-3] using antisymmetrized molecular dynamics (AMD) suggest the existence of a linear chain configuration in $^{14}$C, where $\alpha$-particles are bound by neutrons. This configuration is expected to be associated with a rotational band (J = 0$^+$, 2$^+$, 4$^+$) appearing a few MeV above the $^{10}$Be+$\alpha$ threshold.
The spectroscopy of $^{14}$C has been extensively investigated and, specifically, studies have been conducted to search for the alpha-chain structure by measuring the $^{10}$Be+$^4$He elastic scattering excitation function [4-6] and, more recently, $^{14}$C breakup reaction [7]. These publication do suggest that states which may be associated to a linear chain configuration of $^{14}$C are, indeed, being observed. These claims, however, suffers, on one hand of a poor time resolution that does not allow the separation of the elastic from the inelastic scattering [4,6], on the other, of a poor energy resolution of the $^{14}$C excitation energy spectrum [7]. As reported in [8], in fact, $^{14}$C posses a large number of states in the excitation energy region of interest.
In this presentation we will report on the results of an elastic scattering $^{10}$Be+$^4$He excitation function experiment, performed at INFN-Laboratori Nazionali del Sud using the most intense $^{10}$Be radioactive beam available worldwide (10$^9$ pps). In this measurement the limitations of the previous experiments have been overcome. The elastic scattering excitation function is unambiguously measured in a broad $^{14}$C excitation energy region (13 MeV-23 MeV) and large c.m. angular range (90$^\circ$ -180$^\circ$), with a c.m. energy resolution of about 50 keV. The inelastic scattering channels to both, the 2$_1^+$ and 0$_2^+$ states in $^{10}$Be, have also been measured. The theoretical analysis has been performed using R-matrix. The possible evidence (or lack of) linear chain in $^{14}$C will be critically discussed.
[1] T. Suhara and Y. Kanada-En’yo Phys. Rev. C 82 044301 (2010)
[2] Baba, T. and Kimura Phys. Rev. C 94, 044303 (2016)
[3] Baba, T. and Kimura, Phys. Rev. C 95, 064318 (2017)
[4] H. Yamaguchi et al. Phys. Lett. B 766, 11 (2017)
[5] A. Fritsch et al. Phys. Rev. C 93, 014321, (2016)
[6] M. Freer et al. Phys. Rev. C 90, 054324, (2014)
[7] Han, J., Ye, Y., Lou, J. et al. Commun Phys 6, 220 (2023)
[8] W. von Oertzen et al. Eur. Phys. J A 21, 193 (2004
