[Triumf-seminars] TRIUMF Colloquium today at 14:00

[TRIUMF Seminars]

Date/Time: Thu 2015-08-20 at 14:00

Location:  Auditorium          

Speaker:   Costel Petrache (University of Paris-Sud)

Title:     Exotic rotations, triaxiality and shape coexistence in A = 130-140 nuclei

Abstract: The existence of triaxial nuclei has been the subject of a long standing debate. The possibility of soft and rigid triaxiality has been proposed very early, and many theoretical and experimental studies have been devoted to this intriguing phenomenon since then. More recently two unique fingerprints of triaxiality in nuclei have been intensively studied: the wobbling motion and the dynamic chirality. We have recently studied the Nd nuclei up to very high spins and identified a multitude of bands, which were interpreted as the manifestation of a stable triaxial nuclear shape, presenting various types of collective motion: tilted axis and principal axis rotation, wobbling motion, chiral bands [1,2]. We will discuss the global features of the investigated nuclei, like the J (2) moments of inertia and their theoretical interpretation, as well as the conclusions we have drawn, some of them quite surprising, from the systematic study of the high-spin structure of the Nd nuclei from 128Nd to 141Nd [2].

The existence of triaxial nuclei has been the subject of a long standing debate. The possibility of soft and rigid triaxiality has been proposed very early, and many theoretical and experimental studies have been devoted to this intriguing phenomenon since then. More recently two unique fingerprints of triaxiality in nuclei have been intensively studied: the wobbling motion and the dynamic chirality. We have recently studied the Nd nuclei up to very high spins and identified a multitude of bands, which were interpreted as the manifestation of a stable triaxial nuclear shape, presenting various types of collective motion: tilted axis and principal axis rotation, wobbling motion, chiral bands [1,2]. We will discuss the global features of the investigated nuclei, like the J (2) moments of inertia and their theoretical interpretation, as well as the conclusions we have drawn, some of them quite surprising, from the systematic study of the high-spin structure of the Nd nuclei from 128Nd to 141Nd [2].

The wobbling motion has been first observed in odd-A triaxial strongly deformed nuclei around Z = 72, N = 94 [3], in which case the odd proton occupying an orbital with high intrinsic angular momentum and having a predominantly particle nature aligns its angular momentum vector along the rotation axis (the medium axis, corresponding to the largest moment of inertia). This type of collective motion is called "longitudinal wobbling", which is different from the recently predicted [4] and observed [5] wobbling motion in odd-A nuclei around Z = 60, N = 74, called "transverse wobbling", in which the odd proton aligns its angular momentum along the short axis of the triaxial rotor, which is perpendicular to the rotation axis. We will discuss