Single-particle and collective excitations in Ni-63Albers, M.; Zhu, S.; Janssens, R. V. F.; Gellanki, Jnaneswari; Ragnarsson, Ingemar; Alcorta, M.; Baugher, T.; Bertone, P. F.; Carpenter, M. P.; Chiara, C. J.; Chowdhury, P.; Deacon, A. General rights Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.• Users may download and print one copy of any publication from the public portal for the purpose of private study or research.• You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal Ca,2α3nγ ) 63 Ni reaction at beam energies between 275 and 320 MeV. Three collective bands, built upon states of single-particle character, were identified. For two of the three bands, the transition quadrupole moments were extracted, herewith quantifying the deformation at high spin. The results have been compared with shell-model and cranked Nilsson-Strutinsky calculations. Despite the Z = 28 shell closure and the approach to the purported N = 40 subshell, the 63 Ni isotope is able to sustain collective excitations at moderate and high spin.

The exact nature of the lowest K π =2 + rotational bands in all deformed nuclei remains obscure. Traditionally they are assumed to be collective vibrations of the nuclear shape in the γ degree of freedom perpendicular to the nuclear symmetry axis. Very few such γ-bands have been traced past the usual back-bending rotational alignments of high-j nucleons. We have investigated the structure of positive-parity bands in the N=90 nucleus 156 Dy, using the 148 Nd(

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The rare phenomenon of nuclear wobbling motion has been investigated for the nucleus 187 Au. A longitudinal wobbling-bands pair has been identified and clearly distinguished from the associated signature-partner band on the basis of angular distribution measurements. Theoretical calculations in the framework of the Particle Rotor Model (PRM) are found to agree well with the experimental observations. This is the first experimental evidence for longitudinal wobbling bands where the expected signature partner band has also been identified, and establishes this exotic collective mode as a general phenomenon over the nuclear chart.Wobbling is a collective mode that may appear when the moments of inertia of all three principal axes of the nuclear density distribution are unequal. The mode is well known in classical mechanics and its occurrence is a clear signal for a triaxial nuclear shape. For a given angular momentum, uniform rotation about the axis with the largest moment of inertia corresponds to minimal energy. At a somewhat larger energy, this axis precesses (wobbles) about the space-fixed angular momentum axis. In a quantal system such as the nucleus (or a molecule), the mode manifests itself in the appearance of rotational bands that correspond to successive excitations of wobbling phonons, n ω , and alternating signature α = α 0 + n ω , which determines the spin sequence I = α + even number. Adjacent wobbling bands n ω+1 and n ω are connected by collectively-enhanced ∆I = 1 transitions of predominantly E2 character, which are generated by the wobbling motion of the entire charged body. This is in contrast with the signature-partner bands, which represent another type of excitation involving a partial dealignment of the odd particle with respect to its preferred axis; for those, the connecting ∆I = 1 transitions are of predominantly M1 character, with very little, if any, E2 admixtures.Although predicted quite sometime ago [1], this exotic nuclear motion has been observed only rarely in experiments so far, and the list of nuclei exhibiting it is quite short: 105 Pd [2], 135 Pr [3, 4] (and, possibly, 133 La [5]), 161 Lu [6], 163 Lu [7, 8], 165 Lu [9], 167 Lu [10] and 167 Ta [11]-a total of only 7(8) nuclei across the entire nuclear chart.All the aforementioned nuclei have an odd proton occu-pying a high-j orbital, which modifies the wobbling mode. Frauendorf and Dönau [12] classified this coupled mode as "longitudinal wobbling" (LW) and "transverse wobbling" (TW) when, respectively, the odd particle aligns its angular momentum along the medium axis (the axis with the largest moment of inertia), or along one of the perpendicular axes. The wobbling energy, E wobb [see Eq.(1) below], increases with increasing angular momentum for LW while it decreases for TW [12]. In all of the cases mentioned above (except, possibly, 133 La[5]), the wobbling bands have been identified as corresponding to TW because E wobb decreases with increasing angular momentum. We report on the observation of bands structures corresponding to...