# Rotational bands in the doubly odd 138Pm

TL;DR: In this article, the doubly odd 138Pm nucleus was investigated using the 115In(28Si, 2p3n)138Pm reaction at a beam energy of 145 MeV, and the experimental level properties have been compared to theoretical calculations performed within the Particle Rotor Model (PRM) with axial core and cranked shell model.

Abstract: The band structures of the doubly- odd 138Pm nucleus have been investigated using the 115In(28Si, 2p3n)138Pm reaction at a beam energy of 145 MeV. The three previously known rotational bands viz., (i) the yrast one based on the πh 11 2 ⊗ νh 11 2 configuration, (ii) a ΔI = 2 band with πh 11 2 ⊗ ν[400] 1 2 + configuration at lower frequency but with a change in the neutron configuration to ν[660] 1 2 + at higher frequency, and (iii) one consisting of stretched E2 cascades at lower frequency but of dipole transitions after backbend and with suggested configuration of π[413] 5 2 + ⊗ νh 11 2 have been modified and extended to higher spins. Two new bands have been identified. Of these, one consists of only quadrupole transitions, similar to that observed in band (iii), mentioned above, while the other consists of dipole transitions. The observed level properties have been compared to theoretical calculations performed within the Particle Rotor Model (PRM) with axial core and cranked shell model. The experimental branching ratios and B (M1) , B (E2) ratios of the transitions in the yrast band are well reproduced by PRM, assuming an axial prolate core.

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TL;DR: In this article, experimental nuclear structure data from various reactions and decays are compiled and evaluated for all known nuclides with mass number A=138 (Sn,Sb,Te,I,Xe,Cs,Ba,La,Ce,Pr,Nd,Pm,Sm,Eu,Gd,Tb).

Abstract: © 2017 Elsevier Inc. Experimental nuclear structure data from various reactions and decays are compiled and evaluated for all known nuclides with mass number A=138 (Sn,Sb,Te,I,Xe,Cs,Ba,La,Ce,Pr,Nd,Pm,Sm,Eu,Gd,Tb). Detailed evaluated nuclear structure information is presented for each reaction and decay and the best values combining all available data are recommended for level energies, half-lives, γ-ray energies and intensities, decay properties (energies, intensities and placement of radiations), and other spectroscopic properties. This work supersedes the previous full evaluation of A=138 by A.A. Sonzogni (2003So13).

24 citations

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Jilin University

^{1}TL;DR: In this article, a positive-parity side band with the same configuration as that of the yrast band was observed in the Pm reaction at a beam energy of 105 MeV.

Abstract: High-spin states of $^{138}\mathrm{Pm}$ have been populated using the $^{124}\mathrm{Te}(^{19}\mathrm{F},\phantom{\rule{0.28em}{0ex}}5\mathrm{n})^{138}\mathrm{Pm}$ reaction at a beam energy of 105 MeV. A new positive-parity side band with the same $\ensuremath{\pi}{h}_{11/2}\ensuremath{\bigotimes}\ensuremath{
u}{h}_{11/2}$ configuration as that of the yrast band is observed in $^{138}\mathrm{Pm}$. The properties of the two positive-parity bands show general agreement with the fingerprints of chiral rotation and thus these two bands are suggested to be candidates for near degenerate chiral doublet bands. Besides, odd-even spin staggering of the $\ensuremath{\pi}{h}_{11/2}\ensuremath{\bigotimes}\ensuremath{
u}{h}_{11/2}$ bands is studied systematically in odd-odd Cs, La, Pr, and Pm isotopes. As a result of this study we suggest that the spin value of lowest observed state of the yrast band be reassigned as 9 in $^{138}\mathrm{Pm}$. This new spin assignment is also supported by the argument of alignment additivity.

16 citations

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TL;DR: In this article, the doubly odd 138Pr nucleus has been investigated using the 128Te(14N, 4n)138Pr reaction at a beam energy of 55-65 MeV.

Abstract: The band structures of the doubly odd 138Pr nucleus have been investigated using the 128Te(14N, 4n)138Pr reaction at a beam energy of 55-65 MeV. Altogether six distinct structures have been established, of which the lower part of the yrast band and two side bands were known from earlier works. The observed level properties of the members of the yrast band have been compared with theoretical calculations performed within the Particle Rotor Model (PRM) with axially symmetric core. The experimental branching ratios and B(M1)/B(E2) values when compared with the theoretical results of the PRM, suggest an oblate core.

6 citations

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TL;DR: In this article, a nonadiabatic quasiparticle approach for the description of rotational states in triaxial deformed odd-odd nuclei is proposed, where the residual interaction between the valence proton and neutron is incorporated in two reliable ways, namely, the constant potential form and the zero-range interaction.

Abstract: A large wealth of data and a variety of models led to significant progress in understanding the spectra of deformed nuclei. However, a robust theoretical approach, which is less reliant on adjustable parameters is still elusive. Due to the scarcity of data, this drawback gets more pronounced while studying the exotic nuclei. With the motive to overcome this difficulty, we have developed the nonadiabatic quasiparticle approach for the description of rotational states in triaxial deformed odd–odd nuclei. The rotation-particle coupling is carried out utilizing an appropriate basis transformation such that the matrix elements of the odd–odd system can be written in terms of the rotor energies. This provides the advantage of studying the role of core more efficiently as compared to the conventional particle rotor model. The residual interaction between the valence proton and neutron is incorporated in two reliable ways, namely, the constant potential form and the zero-range interaction.

6 citations

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TL;DR: In this article, the high-spin states of 140Pm have been investigated through the reaction 126Te(19F, 5n) at a beam energy of 90 MeV.

Abstract: The high-spin states of 140Pm have been investigated through the reaction 126Te(19F, 5n) at a beam energy of 90 MeV. A previous level scheme based on the 8− isomer has been updated with spin up to 23 . A total of 22 new levels and 41 new transitions were identified. Six collective bands were observed. Five of them were expanded or re-constructed, and one of them was newly identified. The systematic signature splitting and inversion of the yrast πh11/2⊗νh11/2 band in Pr and Pm odd–odd isotopes has been discussed. Based on the systematic comparison, two ΔI = 2 bands were proposed as double-decoupled bands; other two bands with strong ΔI = 1 M1 transitions inside the bands were suggested as oblate bands with γ ~ −60°; another band with large signature splitting has been proposed with oblate-triaxial deformation with γ ~ −90°. The characteristics for these bands have been discussed.

4 citations

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TL;DR: In this article, the yrast spectra of the nuclides 68 ≦ Z ≦ 70, 89 ≦ N ≦ 99 were analyzed in terms of quasiparticle configurations in a deformed field rotating with the frequency ω, and the excitation energy, e', in the rotating frame (Routhian) and the aligned angular momentum, i, relative to the ground state band as functions of ω were extracted from the experimental rotational bands which were classified with respect to their signature, α, and parity, π.

Abstract: The yrast spectra of the nuclides 68 ≦ Z ≦ 70, 89 ≦ N ≦ 99 are analysed in terms of quasiparticle configurations in a deformed field rotating with the frequency ω. The excitation energy, e', in the rotating frame (Routhian) and the aligned angular momentum, i, relative to the ground state band as functions of ω are extracted from the experimental rotational bands which are classified with respect to their signature, α, and parity, π. These experimental quantities are compared with the ones calculated from the quasiparticle level diagrams. Phenomena like backbending and the occurrence of aligned bands in both even-even and odd-mass nuclei and their mutual relationship are interpreted in terms of quasiparticle configurations that may cross each other with increasing frequency.

576 citations

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TL;DR: In this article, the π[541] 3 2 − (α=± 1 2 )⊗ν[514] 9 2 − and π [423] 5 2 + ⊗n[514]-9 2 − configurations have been extended to higher spins.

Abstract: The band structures of the doubly odd 134 Pr nucleus has been investigated via the 119 Sn( 19 F,4n) 134 Pr and 110 Pd( 28 Si,p3n) 134 Pr reactions at beam energies of 87 and 130 MeV, respectively. The three previously known rotational bands based on the π[541] 3 2 − (α=± 1 2 )⊗ν[514] 9 2 − and π[423] 5 2 + ⊗ν[514] 9 2 − configurations have been extended to higher spins. The difference of ≈2ħ in the experimental alignment of the bands based on the signature partners of the [541] 3 2 − h 11 2 proton orbital is discussed in terms of shape coexistence and coupling with the γ-phonon but no consistent interpretation can be found. A new band consisting of quadrupole transitions has also been identified and linked unambiguously to the low-lying levels of the yrast band. Total routhian surface and cranked shell model calculations suggest a (π h 11 2 ) 3 ⊗ν[530] 1 2 − configuration for this band. The experimental ratios of reduced transition probabilities B( M 1) B( E 2) of the various rotational structures are compared to the theoretical values obtained from a semiclassical model and from the two-particle plus triaxial-rotor model.

74 citations

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55 citations

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TL;DR: In this article, excited states in the odd-odd nuclei 128,130La have been investigated to high spin using gamma-ray spectroscopy, and two distinct bands are seen, one based on a pi h11/2(X) nu h 11/2/2 structure and the other based on pi h 11 /2/X/nu g7/2 configuration.

Abstract: Excited states in the odd-odd nuclei 128,130La have been investigated to high spin using gamma -ray spectroscopy. Two distinct bands are seen, one based on a pi h11/2(X) nu h11/2 structure and the other on a pi h11/2(X) nu g7/2 configuration. Backbends are observed in both configurations for both nuclei and the nature of the particles responsible can be conclusively proved. Experimental variation in the energy-level signature splitting and B(M1)/B(E2) ratios are discussed in terms of the polarising effects of the odd proton and odd neutron on the soft collective core. The results are discussed in terms of the cranked shell model, odd-odd particle-rotor calculations and total Routhian surface calculations. They are also compared to neighbouring odd and odd-odd systems.

23 citations

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TL;DR: In this paper, two distinct high-spin structures have been identified: the first is based on the alignment of a pair of h/sub 11/2/ protons, and the second is a 3-quasiparticle configuration with no signature splitting.

Abstract: The low-lying band structure of /sup 135/Nd has been extended to higher spins using the /sup 112/Cd(/sup 27/Al,p3n..gamma..)/sup 135/Nd and /sup 116/Sn(/sup 24/Mg,2p3n..gamma..)/sup 135/Nd reactions. Two distinct high-spin structures have been identified. The ..delta..J = 1 band built on the ..nu..h/sub 11/2/(514)(9/2)/sup -/ ground state was observed to have a band crossing at J/sup ..pi../ = (25/2)/sup -/. This band crossing is associated with a loss of the moderate signature splitting found below the backbend. Cranked-shell model calculations suggest that this structure involves the alignment of a pair of h/sub 11/2/ protons and that the loss of signature splitting can be attributed to a shape change from a triaxial shape at low spins to a prolate axial shape above the backbend. A second ..delta..J = 1 band structure with no signature splitting was observed to be built on a J/sup ..pi../ = (17/2)/sup (+)/ state at 1954 keV. Values for the ratios of reduced transition rates B(M1; I ..-->..I-1)/B(E2; I..-->..I-1) and B(M1; I..-->..I-1)/B(E2; I..-->..I-2) have been extracted from transitions in the two bands. Comparisons with theoretical predictions helped in the identification of the structure of the second ..delta..J = 1 band, which is thought to be based on a ..nu..h/submore » 11/2/x..pi..h/sub 11/2/x..pi..g/sub 7/2/ three-quasiparticle configuration.« less

19 citations