Mixed-symmetry octupole and hexadecapole excitations in N=52 isotones (original) (raw)

Fine structure of proton-neutron mixed symmetry states in someN=80isotones

Physical Review C, 2008

A microscopic multiphonon approach is adopted to investigate the structure of some low-lying states observed experimentally in the N = 80 isotones 134 Xe, 136 Ba and 138 Ce. The calculation yields levels and electromagnetic transition strengths in good agreement with experiments and relates the observed selection rules to the neutron-proton symmetry and phonon content of the observed states. Moreover, it ascribes the splitting of the M 1 strength in 138 Ce to the proton subshell closure which magnifies the role of pairing in the excitation mechanism.

MIXED SYMMETRY STATES IN 96 MO AND 98 RU ISOTONES IN THE FRAMEWORK OF INTERACTING BOSON MODEL

3C Empresa. Investigación y pensamiento crítico. ISSN: 2254-3376, 2023

Abstract: The software package IBM code for interacting boson model-1 and Neutron Proton Boson NPBOS code for interacting boson model-2 have been used to calculate energy levels, for (_42^96)Mo and (_44^98)Ru by estimating a set of parameters which are used to predict the behavior of even-even isotones (_42^96)Mo and (_44^98)Ru . within the current scope of work there is clear competition between the two parameters (ε and a_2) in (_42^96)Mo and (_44^98)Ru isotones, as an inverse relationship. This means that vibrational qualities are continuous mixed with the rotational properties. In interacting boson model-2 parameters(ε,κ,〖 χ〗_π and χ_ν) have been shown similarity with interacting boson model-1 expected. The Majorana parameter effect (ζ_2) on the calculated excitation energy level for (_42^96)Mo and (_44^98)Ru isotones has been accomplished by vary the ζ_2 around the optimum-matches to practical data. The effect of increasing ζ_2 on mixing symmetry states is the same in all isotones but different from state to another, we find the state J^+ =〖2_3〗^+ was the lowest mixing symmetry states still approximately constant in the all. In that time ,(_42^96)Mo and (_44^98)Ru isotones have 1^+ 〖,3^+〗_1,〖5^+〗_1 mixed symmetry states, rapidly increasing with increasing ζ_2. The results of the calculated energy levels were in acceptable agreement with the experimental data. There is no pure vibrational property of these isotones

New high-spin states of 147Nd and 145Ce: Octupole correlation in the N = 87 isotones

The European Physical Journal A, 2005

High-spin states of the N = 87 nuclei, 147 Nd and 145 Ce, have been populated in the 12 C + 238 U and 18 O + 208 Pb fusion-fission reactions at 90 MeV and 85 MeV bombarding energy, respectively. The emitted γ-radiation was detected using the Euroball III and IV arrays. High-spin states of the 147 Nd isotope have been identified for the first time. The high-spin yrast and near-to-yrast structures of the 145 Ce nucleus have been considerably extended. The newly observed structures, discussed by analogy with the neighbouring isotones, show the coupling of an h 9/2 neutron to the quadrupole and octupole excitations of the core. PACS. 21.10.-k Properties of nuclei; nuclear energy levels-21.10.Re Collective levels-23.20.Lv γ transitions and level energies-27.60.+j 90 ≤ A ≤ 149

Isospin character of the first quadrupole transition in the A~ 100 region

mi.infn.it

Angular distributions for the inelastic scattering of 13 MeV deuterons were obtained for states of 99, 101 Ru at low excitation energies at the São Paulo Pelletron Accelerator-Enge Magnetic Spectrograph facility. The excellent resolution of ~ 8 keV achieved was important for the good definition of the minimum of the Coulomb-Nuclear Interference (CNI) in the angular distribution. This, in turn, permitted the characterization of the parentage of the states in the odd nuclei with respect to the first quadrupole excitations of the cores through a macroscopic analysis. The analysis employs the Distorted Wave Born Approximation formalism, taking the Deformed Optical Model as transition potential, under well established global optical parameters. Values of the mass deformation length N L δ and the ratio between charge and mass deformation lengths C 2 were extracted by fitting the predictions to the experimental angular distributions. The values of C 2 are larger than 1.2 in 99 Ru and 1.3 in 101 Ru, indicating a decrease as a neutron pair is added, of the contribution of the neutrons relative to that of the protons, in the first quadrupole excitation in the odd isotopes, when compared to that previously measured in the even ones.

Octupole and quadrupole structures in the N=88 nucleus 152Gd

2018

The spectroscopy of 152Gd has been studied using the 150Sm(α, 2n)152Gd fusion evaporation reaction at a beam energy of 25 MeV. The emitted γ-rays were detected using the AFRODITE γ-ray spectrometer, equipped with 9 escape-suppressed clover detectors, at iThemba LABS. DCO ratios and linear polarization measurements were used to determine the spins and parities of new levels and confirm the assignments of previously established levels. We report an observation of consistent out-of-band E1 transitions decaying both to and from the K=02 band and the octupole band. These out-of-band E1 transitions suggest that there is strong octupole correlations between the K=02 and octupole band. The phenomenon of congruent band structures built between the K=02 band and the ground band is investigated and the results are discussed. In order to get a better insight on the microscopic behaviour of the lowest negative parity bands across the A∼144 to 158 mass region, a systematic review has been carried...

Low-lying level structure of the neutron-unbound N=7 isotones

Physical Review C, 2020

This article reports on results of an experimental search for ground state shell inversion in the neutron-unbound N = 7 isotones 9 He and 10 Li. Two different radioactive ion beams (11 Be, E lab = 44 MeV/u and 12 B, E lab = 45 MeV/u) impinging on a beryllium target were used to directly and selectively populate unbound states of a given in the nuclides of interest. Be(11 Be, 8 He +n) and Be(12 B, 8 He +n) reactions populated unbound states in 9 He. Fragments and neutrons were detected in coincidence to reconstruct the decay energy of 9 He using invariant mass spectroscopy. Similarly, Be(11 Be, 9 Li +n) and Be(12 B, 9 Li +n) reactions were used to populate unbound states in 10 Li, and the time-of-flight method was used to determine the relative velocity of the 9 Li fragments and neutrons in coincidence. Various states in both 9 He and 10 Li were observed and characterized. The data indicate possible ground state shell inversion in both cases.

Decay of quadrupole-octupole1−states inCa40andCe140

Physical Review C

Background: Two-phonon excitations originating from the coupling of two collective one-phonon states are of great interest in nuclear structure physics. One possibility to generate low-lying E1 excitations is the coupling of quadrupole and octupole phonons. Purpose: In this work, the γ-decay behavior of candidates for the (2 + 1 ⊗ 3 − 1) 1 − state in the doublymagic nucleus 40 Ca and in the heavier and semi-magic nucleus 140 Ce is investigated. Methods: (γ, γ) experiments have been carried out at the High Intensity γ-ray Source (HIγS) facility in combination with the high-efficiency γ-ray spectroscopy setup γ 3 consisting of HPGe and LaBr3 detectors. The setup enables the acquisition of γ-γ coincidence data and, hence, the detection of direct decay paths. Results: In addition to the known ground-state decays, for 40 Ca the decay into the 3 − 1 state was observed, while for 140 Ce the direct decays into the 2 + 1 and the 0 + 2 state were detected. The experimentally deduced transition strengths and excitation energies are compared to theoretical calculations in the framework of EDF theory plus QPM approach and systematically analyzed for N = 82 isotones. In addition, negative parities for two J = 1 states in 44 Ca were deduced simultaneously. Conclusions: The experimental findings together with the theoretical calculations support the two-phonon character of the 1 − 1 excitation in the light-to-medium-mass nucleus 40 Ca as well as in the stable even-even N = 82 nuclei.

Anomalies are viewed in nuclear structure of N = 90 isotones

Journal of emerging technologies and innovative research, 2018

The trixiality is noticed in the structure of N = 90 isotones with ϒ- band energy staggering. The S(4) staggering is predicting the structure . The plot of staggering factor S(4) with N highlights the anomaly.