Ponente
Descripción
Cluster-like structures are often present in atomic nuclei and significantly influence their structural and dynamical properties. More precisely, Morinaga [1] proposed a particular alpha cluster configuration known as the linear-chain cluster state (LCCS), in which the alpha particles are arranged in a linear sequence. In this configuration, the neutron excess appears to play a significant role in stabilizing the structure. Suhara and Kanada-En'yo [2] were the first to predict the existence of the LCCS in $^{14}$C using antisymmetrized molecular dynamics (AMD). However, it was not until 2014 that the first experimental evidence was obtained by Freer et al. [3], supporting the idea of the LCCS in $^{14}$C by identifying the prolate band (J$^{\pi}$ = $0^+$, $2^+$, 4$^+$). Two years later, Fritsch et al. [4] observed the 2$^+$ and the 4$^+$ states, but the position of the band head (0$^+$) remained unknown. Recently, Yamaguchi et al. [5] reported having identified this 0$^+$ state at 3 MeV, however, a recent work has challenged this finding [6].
The alpha-cluster structure of $^{14}$C has been investigated through the resonance scattering in the $^{10}$Be($^{4}$He,$^{4}$He)$^{10}$Be reaction. The experiment was conducted using an active target time projection chamber (AT-TPC) filled with pure He, placed inside the solenoidal spectrometer SOLARIS [7]. The standalone $^{10}$Be beam was injected into the ReA6 accelerator at the Facility for Rare Isotope Beams (FRIB), where it was accelerated and subsequently delivered to SOLARIS. Different gas pressures inside the AT-TPC and different beam energies were used in order to extract as much information as possible about the different LCCS bands: the $\pi$-bond and the $\sigma$-bond. Both bands will be studied using a new observable: the three-particle decay inelastic channel branching ratio.
[1] H. Morinaga, Interpretation of some of the excited states of 4n self-conjugate nuclei, Phys. Rev. 101 (1956) 254-258.
[2] T. Suhara, Y. Kanada-En'yo, Cluster structures of excited states in C 14, Physical Review C 82 (2010) 044301.
[3] M. Freer et al., Resonances in 14C observed in the 4He(10Be,4He)10Be reaction, Physical Review C 90 (2014) 054324.
[4] A. Fritsch et al., One dimensionality in atomic nuclei: A candidate for linear-chain $\alpha$ clustering in C 14, Physical Review C 93 (2016) 014321.
[5] H. Yamaguchi et al., Experimental investigation of a linear-chain structure in the nucleus 14C, Physics Letters, Section B: Nuclear, Elementary Particles and High-Energy Physics 766 (2017) 11-16.
[6] J. Han et al., Nuclear linear-chain structure arises in carbon-14. Commun Phys 6, 220 (2023).
[7] https://www.anl.gov/phy/solaris.
This work is supported by the Xunta de Galicia (CIGUS Network of Research Centres) and the European Union.
