Quantal rotation and its coupling to intrinsic motion in nuclei

Abstract

Abstract. Symmetry breaking is an importance concept in nuclear physics and other fields of physics. Self-consistent coupling between the mean-field potential and the single-particle motion is a key ingredient in the unified model of Bohr and Mottelson, which could lead to a deformed nucleus as a consequence of spontaneous breaking of the rotational symmetry. Some remarks on the finite-size quantum effects are given. In finite nuclei, the deformation inevitably introduces the rotation as a symmetry-restoring collective motion (Anderson-Nambu-Goldstone mode), and the rotation affects the intrinsic motion. In order to investigate the interplay between the rotational and intrinsic motions in a variety of collective phenomena, we use the cranking prescription together with the quasiparticle random phase approximation. At low spin, the coupling effect can be seen in the generalized intensity relation. A feasible quantization of the cranking model is presented, which provides a microscopic approach to the higher-order intensity relation. At high spin, the semiclassical cranking prescription works well. We discuss properties of collective vibrational motions under rapid rotation and/or large deformation. The superdeformed shell structure plays a key role in emergence of a new soft mode which could lead to instability toward the K π = 1 − octupole shape. A wobbling mode of excitation, which is a clear signature of the triaxiality, is discussed in terms of a microscopic point of view. A crucial role played by the quasiparticle alignment is presented.

Collective Inertial Masses in Nuclear Reactions

“…Another important issue is the inclusion of the paring correlation, which may influence not only static but also dynamical nuclear properties. In order to keep the lowest-energy configuration during the collective motion, the pairing interaction is known to play a key role [30]. Therefore, we may expect significant impact on both the collective inertial masses and the reaction paths.…”

Influence of moments of inertia on transverse wobbling mode in odd-mass nuclei

“…On the theoretical side, the wobbling excitation got extensive descriptions with the particle rotor model (PRM) [16,[21][22][23][24][25][26] and its approximation solutions [27][28][29][30][31][32][33][34][35][36]. In addition, the random phase approximation [37][38][39][40][41][42][43][44][45], the angular momentum projection method [11,14,46], and the collective Hamiltonian method [47][48][49] are used to discuss this issue. However, it should be noted that there are still increasingly loud debates on the transverse wobbling in odd-mass nuclei.…”

Two quasiparticle wobbling in the even-even nucleus 130Ba

“…The cranking mean-field model yields only the lowest state for a given configuration and, thus, one has to go beyond the mean-filed level to describe the wobbling excitations. This has been done 2 by incorporating the quantum correlations by means of random phase approximation (RPA) [20,21] or by the angular momentum projection methods [22,15]. The projected shell model (PSM) carries out the shell-model configuration mixing based on Nilsson mean field with the angular momentum projection technique [23].…”