The band built on the K-pi = 8(-), T-1/2 = 9.4 ms isomer of( 130)Ba has been identified, filling the gap in the systematics of the dipole bands built on the 8(- )isomers in the N = 74 isotones from( ...128)Xe to Gd-138. The use of the GALILEO array in conjunction with its ancillaries EUCLIDES and Neutron Wall, helped to firmly place the newly identified transitions on top of the long-lived isomer. The extracted g(K)and g(R) gyromagnetic factors are in agreement with the 7/2(+)404 circle times 9/2(-)514 two-neutron Nilsson configuration. Particle-rotor model calculations give an understanding of the limited degree of K mixing. The experimental information on the K-pi = 8(-) isomer of Ba-130 is now the most complete among the K isomers of the N = 74 isotones.
Superdeformed and Triaxial States in Ca42 Hadynska-Klek, K; Napiorkowski, P J; Zielinska, M ...
Physical review letters,
08/2016, Letnik:
117, Številka:
6
Journal Article
Recenzirano
Shape parameters of a weakly deformed ground-state band and highly deformed slightly triaxial sideband in Ca42 were determined from E2 matrix elements measured in the first low-energy Coulomb ...excitation experiment performed with AGATA. The picture of two coexisting structures is well reproduced by new state-of-the-art large-scale shell model and beyond-mean-field calculations. Experimental evidence for superdeformation of the band built on 02+ has been obtained and the role of triaxiality in the A~40 mass region is discussed. Furthermore, the potential of Coulomb excitation as a tool to study superdeformation has been demonstrated for the first time.
E2 collective properties for the low-lying states in
186,188,190,192Os and
194Pt have been investigated experimentally by means of Coulomb excitation using 3.3–4.8 MeV/nucleon
40Ca,
58Ni,
136Xe and
...208Pb beams. The deexcitation γ rays following Coulomb excitation were detected in coincidence with the scattered particles. Levels with excitation energies up to 3–4 MeV of the ground-state, γ and 4
+ collective bands as well as excited 0
+ states were populated in each nucleus studied. A semiclassical Coulomb-excitation least-squares search code GOSIA was used to extract E2 matrix elements from the measured γ-ray yields. For each nucleus studied, a unique and almost complete set of E2 matrix elements for the low-lying states has been determined, which includes both the magnitudes and signs of the transitional and diagonal matrix elements. The completeness of the set of measured E2 matrix elements makes it possible to determine the intrinsic quadrupole deformation for the low-lying states in these nuclei via a model-independent method. The results indicate clearly that the E2 properties for the low-lying states in these nuclei are correlated well using only the quadrupole collective degrees of freedom. The extracted E2 matrix elements are compared with the prediction of various collective models such as the asymmetric rigid rotor model, the γ-soft model of Leander, and the IBA-2 model. These particular models do not reproduce the data satisfactorily, however the general trends of the data are consistent with the descriptions of γ-soft type collective models through a prolate to oblate shape-transition region. That the enhanced
B(E2) values between the
I,quasi-
K
π
= 4,4
+ state and members of the
I,quasi-
K
π
= 2,2
+ band are well reproduced by the γ-soft model is consistent with the interpretation of the
I,quasi-
K
π
= 4,4
+ state being a two-phonon γ-vibration excitation.
A sequence of nine almost equidistant quadrupole transitions is observed in 137Nd. The sequence represents an extremely regular rotational band that extends to a spin of about 75/2 and an excitation ...energy of ≈ 4.5 MeV above yrast. Here, cranked mean-field calculations of the Nilsson-Strutinsky type suggest an oblate shape for the band. They reproduce the observed I(I + 1) dependence of the rotational energy whereas predicting a pronounced decrease in the deformation, which is the hallmark of antimagnetic rotation.
Lifetimes of the yrast levels with spins
I
π
= 23/2
−
to 39/2
−
in
129
La produced via the
120
Sn(
14
N, 5
n
) reaction at a beam energy of 77MeV have been measured by the Doppler shift attenuation ...method. The properties of the studied levels belonging to the πh
11/2
band were compared with the theoretical predictions obtained in the framework of the core quasi-particle coupling model. It is suggested that the rigid-rotor model used to describe the cores is too simplified as the even-even nuclei from the
A
∼ 130 region are susceptible to shape deformation. Reasonable agreement was obtained with the phenomenological cores based on the experimental data of
128
Ba.
Multiple chiral bands in 137 Nd Petrache, C. M.; Lv, B. F.; Chen, Q. B. ...
The European physical journal. A, Hadrons and nuclei,
2020, Letnik:
56, Številka:
8
Journal Article
Recenzirano
Two new bands have been identified in 137Nd from a high-statistics JUROGAM II gamma-ray spectroscopy experiment. Constrained density functional theory and particle rotor model calculations are used ...to assign configurations and investigate the band properties, which are well described and understood. It is demonstrated that these two new bands can be interpreted as chiral partners of previously known three-quasiparticle positive- and negative-parity bands. The newly observed chiral doublet bands in 137Nd represent an important support to the existence of multiple chiral bands in nuclei. The present results constitute the missing stone in the series of Nd nuclei showing multiple chiral bands, which becomes the most extended sequence of odd–even and even-even nuclei presenting multiple chiral bands in the Segré chart.
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