Ponente
Descripción
Carbon isotopes provide a rich testing ground for the evolution of shell structure and halo phenomena in light neutron-rich nuclei. In particular, $^{15}\mathrm{C}$ [1] is a well-known one-neutron halo candidate, with the valence neutron weakly bound ($S_n \approx 1.2$ MeV) in a $2s_{1/2}$ orbital.
Its first excited state at 0.74 MeV has a dominant single-particle configuration with a neutron in the $1d_{5/2}$ orbital and a lifetime of 2.61 ns [2]. The transition between these states is expected to involve weak core polarization due to the inert $^{14}\mathrm{C}$ core, which may be further reduced by the spatial decoupling of the halo neutron. Understanding how the halo in $^{15}\mathrm{C}$ impacts core polarization is directly relevant for constraining the quadrupole moments of $^{16}\mathrm{C}$ [3].
To address these questions, we studied the one-neutron transfer $^{16}\mathrm{C}(p,d)^{15}\mathrm{C}$, the two-neutron transfer $^{16}\mathrm{C}(p,t)^{14}\mathrm{C}$, and the deuteron-induced transfer $^{16}\mathrm{C}(d,t)^{15}\mathrm{C}$. These complementary reactions provide sensitivity to single-particle and pairing correlations in neutron-rich carbon isotopes and serve as benchmarks for theoretical models of transfer reactions with exotic beams.
The experiment was performed in 2023 at the Argonne Tandem Linac Accelerator System [4] (ATLAS) using the Active Target Time Projection Chamber (AT-TPC) [5] and HELIOS solenoidal spectrometer [6,7]. A primary $^{18}\mathrm{O}$ beam with an energy of $222.72 \pm 0.43$ MeV was degraded to produce a $^{16}\mathrm{C}$ secondary beam, which was subsequently used to study these transfer channels.
This work has received financial support from the Xunta de Galicia (CIGUS Network of Research Centres) and the European Union. This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics, under Contracts No. DE-AC02-06CH11357. This research used resources of ANL’s ATLAS facility, which is a DOE Office of Science User Facility.
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References:
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