Speaker
Description
Last years the toroidal dipole resonance (TDR) attracts a high attention [1-4]. This mode is located at the energy of the pygmy dipole resonance and is believed to form the low-energy part of the isoscalar giant dipole resonance. The TDR is the only known dipole {\it vortical} mode in the family of intrinsic electric excitations.Just TDR perhaps generates the pygmy dipole resonance at the nuclear surface region [3]. Last years, various TDR properties were explored by our group within the self-consistent Skyrme Quasiparticle Random-Phase Approximation (QRPA), see review [4].However the TDR still has many open problems and even its experimental observation can be disputed [5].
In this connection, we propose a new route to study the toroidal mode: to switch the effort from TDR (embracing many states and masked by other multipole modes) to {\it individual} well-separated low-energy toroidal states. As was recently shown [6], such states can exist in low-energy spectra of light nuclei with a strong axial prolate deformation. For example, in 24Mg, this state appears as the lowest dipole K=1 excitation. These states can be easier discriminated and identified in experiment than TDR. Being observed, they could serve as excellent test cases to probe various reactions for vortical nuclear excitations. As a first step, we discus the possibility to observe the toroidal individual states in inelastic electron scattering.
[1] N. Paar, D. Vretenar, E. Khan, and G. Colo,
Rep. Prog. Phys. v70, 691 (2007).
[2] J. Kvasil, V.O. Nesterenko, W. Kleinig, P.-G. Reinhard, and P. Vesely,
Phys. Rev. C84, 034303 (2011).
[3] A. Repko, P.-G. Reinhard, V.O. Nesterenko, and J. Kvasil,
Phys. Rev. C87, 024305 (2013).
[4] V.O. Nesterenko, J. Kvasil, A. Repko, W. Kleinig, and P.-G. Reinhard,
Phys. Atom. Nucl. v.79, 842 (2016).
[5] A. Repko, J. Kvasil, V.O. Nesterenko, and P.-G. Reinhard,
Eur. Phys. J. A53, 221 (2017).
[6] V.O. Nesterenko, A. Repko, J. Kvasil, and P.-G. Reinhard,
Phys. Rev. Lett. v.120, n.18, 182501 (2018).
