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Journal ArticleDOI

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.
About: This article is published in Nuclear Physics.The article was published on 1998-03-23. It has received 9 citations till now. The article focuses on the topics: Yrast.
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Journal ArticleDOI
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).

24 citations

Journal ArticleDOI
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

Journal ArticleDOI
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

Journal ArticleDOI
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

Journal ArticleDOI
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

References
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Journal ArticleDOI
E. S. Paul1, C. W. Beausang1, D. B. Fossan1, R. Ma1, W. F. Piel1, Weng Pk1, N. Xu1 
TL;DR: In this article, a rotational band based on two-and four-quasiparticle configurations was observed to backbend sharply at a frequency h-dash-bar..omega.. = 0.34 MeV due to the alignment of a pair of h/sub 11/2/ protons.
Abstract: High-spin states have been populated in /sup 136/Nd using the /sup 116/Cd(/sup 24/Mg,4n..gamma..) /sup 136/Nd reaction. Several rotational bands have been observed based on two- and four-quasiparticle configurations. The ground-state band backbends sharply at a frequency h-dash-bar..omega.. = 0.34 MeV due to the alignment of a pair of h/sub 11/2/ protons. Both signatures of a negative parity side band based on a ..pi..h/sub 11/2/x..pi..g/sub 7/2/ configuration were observed to backbend at a frequency h-dash-bar..omega.. = 0.44 MeV, again due to the alignment of a pair of h/sub 11/2/ protons. All these bands are prolate because of the stabilizing influence of the h/sub 11/2/ quasiprotons on the ..gamma..-soft core. In addition to the h/sub 11/2/ proton alignment in the ground-state band, a rotational band is observed built on a second 10/sup +/ state, which involves the alignment of a pair of h/sub 11/2/ neutrons. An alignment of neutrons from the upper h/sub 11/2/ midshell drives the nucleus towards a collectively rotating oblate (..gamma.. = -60/sup 0/) shape. Both signatures of a band based on a ..nu..h/sub 11/2/x..nu..g/sub 7/2/ configuration were observed, also possibly oblate. The observation of both neutron and proton low-frequency alignments is consistent with cranked-shell model calculations and theoreticalmore » estimates of the prolate-oblate energy difference for this nucleus.« less

18 citations

Journal ArticleDOI
TL;DR: In this article, the doubly odd 136Pr nucleus has been investigated via the 136Ce(p,n), 122Sn(19F,5n) and 110Pd(30Si,p3n) reactions at beam energies of 14, 84 and 125 MeV, respectively.

17 citations

Journal ArticleDOI
TL;DR: The breaking of the [ital N]=50 neutron core appears to be a plausible mechanism for the observed high spin states.
Abstract: High spin states in the N=50 nucleus $^{93}\mathrm{Tc}$ were populated and studied using the reaction $^{66}\mathrm{Zn}$ ${(}^{31}$P, 2p2n${)}^{93}$Tc at a beam energy of 115 MeV. Gamma ray intensities and gamma-gamma coincidences were measured. Multipolarities of the transitions were extracted assuming stretched transitions. The positive and negative parity bands have been extended up to spins 39/${2}^{+}$ and 43/${2}^{\mathrm{\ensuremath{-}}}$, respectively. The proposed level scheme above J=25/2 cannot be well understood on the basis of the spherical shell model calculations with valence protons occupying the (1${\mathit{f}}_{5/2}$,2${\mathit{p}}_{3/2}$,2${\mathit{p}}_{1/2}$,1${\mathit{g}}_{9/2}$) configuration space. The breaking of the N=50 neutron core appears to be a plausible mechanism for the observed high spin states.

14 citations

Journal ArticleDOI
C. W. Beausang1, L. Hildingsson1, E. S. Paul1, W. F. Piel1, N. Xu1, D. B. Fossan1 
TL;DR: The level structures of doublyodd nuclei have been studied to high spin following the reactions $^{114}\mathrm{Cd}$${(}^{27}$Al,5n${)}^{136}$Pm, $€116}\mathm{Sn}$$(}€24}$Mg,p3n${)€136}€Pm and $€14}€Pr as mentioned in this paper.
Abstract: The level structures of the doubly-odd nuclei $^{136}\mathrm{Pm}$ and $^{134}\mathrm{Pr}$ have been studied to high spin following the reactions $^{114}\mathrm{Cd}$${(}^{27}$Al,5n${)}^{136}$Pm, $^{116}\mathrm{Sn}$${(}^{24}$Mg,p3n${)}^{136}$Pm, and $^{114}\mathrm{Cd}$${(}^{27}$Al,\ensuremath{\alpha}3n${)}^{134}$Pr. The two nuclei show very similar collective features. In both nuclei a rotational band built on the \ensuremath{\pi}${h}_{11/2}$\ensuremath{\bigotimes}\ensuremath{ u}${h}_{11/2}$ configuration has been observed. This band shows a constant signature splitting of \ensuremath{\sim}50 keV with no backbend in both cases. In addition, a sideband built on the \ensuremath{\pi}${[413](5/2}^{+}$\ensuremath{\bigotimes}\ensuremath{ u}${h}_{11/2}$ configuration has been observed in $^{136}\mathrm{Pm}$. This band becomes yrast at high spins and shows a gain in alignment of \ensuremath{\sim}8\ensuremath{\Elzxh} at a frequency of \ensuremath{\Elzxh}\ensuremath{\omega}\ensuremath{\sim}0.28 MeV due to the decoupling of a pair of ${h}_{11/2}$ protons. In $^{134}\mathrm{Pr}$ the sideband was only observed above the band crossing. Experimental ratios of reduced transition probabilities, B(M1)/B(E2), have been extracted from transitions within the bands and compared to theoretical values obtained from a semiclassical model.

13 citations

Journal ArticleDOI
C. W. Beausang1, Weng Pk1, R. Ma1, E. S. Paul1, W. F. Piel1, N. Xu1, D. B. Fossan1 
TL;DR: High-spin states in the doubly odd nucleus {sup 138}Pm have been studied via gamma-ray spectroscopic methods following the heavy-ion fusion-evaporation reaction.
Abstract: High-spin states in the doubly odd nucleus $^{138}\mathrm{Pm}$ have been studied via gamma-ray spectroscopic methods following the $^{116}\mathrm{Cd}$${(}^{27}$Al,5n\ensuremath{\gamma}) heavy-ion fusion-evaporation reaction. Several rotational bands have been populated in the nucleus. The yrast cascade is based on two signature components of the \ensuremath{\pi}${\mathit{h}}_{11/2}$\ensuremath{\bigotimes}\ensuremath{ u}${\mathit{h}}_{11/2}$ configuration. A sideband was observed, which is probably based on the \ensuremath{\pi}[413]5/${2}^{+}$\ensuremath{\bigotimes}\ensuremath{ u}${\mathit{h}}_{11/2}$ configuration. Similar rotational bands built on these configurations have been observed in the neighboring doubly odd $^{134}\mathrm{Pr}$ and $^{136}\mathrm{Pm}$ nuclei. An additional \ensuremath{\Delta}I=2 band structure, not observed in these other nuclei, has also been populated. At low rotational frequencies, this band is possibly based on the \ensuremath{\pi}${\mathit{h}}_{11/2}$\ensuremath{\bigotimes}\ensuremath{ u}[400]1/${2}^{+}$ configuration. At a frequency \ensuremath{\Elzxh}\ensuremath{\omega}\ensuremath{\sim}0.31 MeV it is crossed by a band based on the favored signature of the \ensuremath{\pi}${\mathit{h}}_{11/2}$\ensuremath{\bigotimes}\ensuremath{ u}${\mathit{i}}_{13/2}$ configuration with an accompanying gain in alignment of \ensuremath{\sim}6\ensuremath{\Elzxh}.

11 citations