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The neutron deficient Xe nuclei with A ≈ 120 are predicted to have strong octupole correlation at low spins. In the present work, an attempt was made to improve upon the level scheme and also to look into the signatures of octupole correlation in 118Xe via high spin γ-ray spectroscopy. High spin states in 118Xe have been populated via 93Nb(28Si,p2n)118Xe fusion-evaporation reaction at a beam energy of 115 MeV provided by the 15 UD pelletron accelerator facility at IUAC, New Delhi. In the experiment, seven new γ-transitions have been found and are placed appropriately in the level scheme. Theoretical study using the triaxial projected shell model (TPSM) approach suggests that the first bandcrossing is due to the alignment of two neutrons, and a parallel band tracking the yrast configuration is the γ-band built on the two-quasiparticle state. Enhanced E1 transition rates measured between opposite parity bands, involving νh11/2 and νd5/2 orbitals having ∆j = ∆l = 3, indicates the presence of octupole correlation in this nucleus

The microscopic origin of the $\gamma$-softness (fluctuations in the triaxiality parameter $\gamma$ of the nuclear shape) observed in atomic nuclei is studied in the framework of the triaxial projected shell model approach, which is based on the deformed mean-field picture with multi-quasiparticle configuration space. It is demonstrated that the coupling to quasiparticle excitations drives the system from a $\gamma$-rigid to a $\gamma$-soft pattern. As an illustrative example for a $\gamma$-soft nucleus, a detailed study has been performed for the $^{104}$Ru nucleus. The experimental energies and a large sample of measured $E2$ matrix elements available for this nucleus are reproduced quite accurately. The shape invariant analysis of the calculated $E2$ matrix elements elucidates the $\gamma$-soft nature of $^{104}$Ru.

In an effort to elucidate the rich band structures observed in odd-neutron systems, triaxial projected shell model approach is extended to include three-quasineutron and five-quasiparticle configurations. This extension makes it possible to investigate the high-spin states up to and including the second band crossing. Detailed investigation has been performed for odd-mass Xe isotopes with the extended basis, and it is shown that character of the band crossing along the yrast line changes with shell filling of the 1h11/2 orbital. Further, it is observed that the three-quasiparticle state that crosses the ground-state configuration, leading to the normal band crossing phenomenon along the yrast line, first crosses the {\gamma} band based on the ground-state configuration at an earlier spin value. This crossing feature explains the occurrence of the signature inversion observed in the {\gamma} bands for some of the studied isotopes.

The study of neutron-deficient Kr isotopes in mass range [Formula: see text]–80, which is in the transitional region, is quite interesting. These isotopes show different structures, particularly in [Formula: see text] shape coexistence near ground state has been observed. In this work, the multi-quasiparticle triaxial projected shell model (TPSM) is employed to study the high spin band structures and to depict [Formula: see text] deformation in [Formula: see text] nucleus. A triaxial configuration is a superposition of several K-states and the projected states result in various bands originating from the same intrinsic configuration. The yrast-, [Formula: see text]- and 2[Formula: see text] bands are studied and explained in the framework of TPSM approach.

In the present work, the basis space in the triaxial projected shell-model approach is expanded to include three and five quasiparticle configurations for odd-proton systems. This extension allows us to investigate the high-spin band structures observed in odd-proton systems up to and including the second band-crossing region and, as a first major application of this development, the high-spin properties are investigated for odd-mass $^{125\ensuremath{-}137}\mathrm{Pr}$ and $^{127\ensuremath{-}139}\mathrm{Pm}$ isotopes. It is shown that band crossings in the studied isotopes have mixed structures with the first crossing dominated by one-proton coupled to two-neutron configuration for the lighter isotopes which then changes to three-proton configuration with increasing neutron number. Furthermore, $\ensuremath{\gamma}$ bands based on quasiparticle states are also delineated in the present work, and it is predicted that these band structures built on three-quasiparticle configurations become favored in energy for heavier systems in the high-spin region.

The present work has been focussed on the application of Projected Shell Model to study the negative parity rotational band structure up to the high spin states of the neutron-rich odd mass Terbium isotopes with neutron numbers ranging from 90 to 98. The structure evolution in these nuclei has been made on the basis of various nuclear structure properties like energy spectra, transition energies, wave functions and electromagnetic transition probabilities (B(E2) and B(M1)). Besides, the occurrence of back bending has also been reported in the present work.

The purpose of the present work is to study the negative parity yrast bands in odd-mass 101−109Cd nuclei in the framework of Projected Shell Model (PSM). The results are obtained for the energy spectrum, reduced transition probabilities [ B ( E 2 ) ], rotational alignment etc. The yrast and excited band spectra of these isotopes are found to arise from the quasiparticle states around the Fermi level. The yrast and excited band spectra are found to depend sensitively on the different single particle and multi-quasiparticle configurations at low- and high-spins respectively. This work also substantiates the observed presence of anti-magnetic rotation in 105,107,109Cd nuclei.

The second-phonon ( n ω = 2 ) wobbling band has been established in the nucleus 135Pr. Conclusive evidence for its wobbling nature comes from the Δ I = 1 , E2 character of the transitions between the new band and the previously identified transverse wobbler band ( n ω = 1 ) in this nucleus. Theoretical calculations in the framework of the quasiparticle triaxial rotor and triaxial projected shell models are found to be in good agreement with the experimental results.

A theoretical study of the nuclear structure of odd-odd 88–96Rb nucleus in the A∼100 mass region is carried out by using the angular-momentum-projection technique implemented in the Projected Shell Model (PSM). For these isotopes, PSM calculations are performed to obtain the yrast spectra and the description of the formation of the yrast level structure from multi-quasi-particle configurations is also presented. The back-bending in moment of inertia and transition energies have also been calculated and compared with the available experimental data. In addition, the reduced transition probabilities, i.e. B(E2) and B(M1), are also obtained for the yrast band of these isotopes for the first time by using PSM wave-functions.

Lifetime measurements have been carried out for the levels of the negative parity yrast sequence in $^{103}\mathrm{Pd}$ nucleus using the Doppler shift attenuation method. The levels were populated via $^{94}\mathrm{Zr}(^{13}\mathrm{C}, 4n\ensuremath{\gamma})^{103}\mathrm{Pd}$ fusion-evaporation reaction at a beam energy of 55 MeV. De-exciting $\ensuremath{\gamma}$ rays were detected by utilizing the Indian National Gamma Array. The extracted transition probabilities and other auxiliary observations indicate that the sequence may be resulting from the antimagnetic rotational (AMR) motion of valence nucleons. The key characteristic feature of the AMR motion is the steady decrease of the $B(E2)$ transition probability with spin, which is seen in the present measured transitions for $^{103}\mathrm{Pd}$. The experimental results are compared with the theoretical predictions of tilted axis cranked approach based on the covariant density functional theory. It is noted that the properties of the AMR band structure for $^{103}\mathrm{Pd}$ predicted in this model analysis are in good agreement with the present experimental findings. Further, semi-classical particle-rotor model has been employed to substantiate the AMR interpretation of the observed band structure in $^{103}\mathrm{Pd}$ and it is shown that results are similar to the band structures observed in the neighboring isotopes, which have also been considered as candidates for AMR motion.

High-spin excited states of $^{135}\mathrm{Pm}$ have been investigated using the $^{107}\mathrm{Ag}(^{32}\mathrm{S}$, $2p2n$) reaction at 145-MeV beam energy. Three negative-parity bands have been investigated up to $\ensuremath{\sim}9.0\ensuremath{-}$, $7.6\ensuremath{-}$, and $6.9\ensuremath{-}\mathrm{MeV}$ excitation energies with spin parities $(55/{2}^{\ensuremath{-}})$, $(49/{2}^{\ensuremath{-}})$, and $(47/{2}^{\ensuremath{-}})\phantom{\rule{4pt}{0ex}}\ensuremath{\hbar}$, respectively. The experimental results have been interpreted using the triaxial projected shell model. It is shown that the observation of the parallel band structures can be explained in terms of crossing of two $s$ bands with the yrast band, which is a rare phenomenon for an odd-$A$ nucleus. Further, the lifetimes of levels in yrast band have been extracted using Doppler shift attenuation method. The evaluated $B(E2)$ values of yrast states show the loss of collectivity at higher spin, attributed to the alignment process.

A systematic study of the positive as well as negative parity yrast structure for the odd-mass 145−149Pm isotopes is carried out by using the angular momentum projection technique implemented in the projected shell model (PSM). By assuming an axial symmetry in the deformed basis, we have been able to calculate the yrast states up to a maximum spin of 47/2 for both positive and negative parity, and as a result, a good agreement is obtained with available experimental data for all isotopes. The intrinsic structure of positive and negative parity yrast states has been found to be built on πg7/2 $$ \otimes $$ νh11/2 and πh11/2 $$ \otimes $$ νh11/2 configurations, respectively. The phenomenon of back-bending has also been discussed in the present work. Reduced electric and magnetic transitions probabilities [B(E2) and B(M1)] are also calculated using the PSM wave functions. Since experimental data on B(E2) and B(M1) are not available, these results can serve as motivation for experimentalists to look for these data. However, the theoretical values of transition strength ratio B(M1)/B(E2) have been found to be matching excellently with the experimental ones.

With the proton number just below the magic number Z = 50, the palladium isotopes are known to exhibit rich nuclear structure phenomena. Inspired by the extensive experimental as well as theoretical structural investigations of Pd isotopes, we have performed the detailed study of band structures of 108–118Pd isotopes using triaxial projected shell model approach employing the multi-quasiparticle configuration space. As the mass region A ~ 110 depicts well-developed yrast, γ- and 2γ-bands, the present work demonstrates the reliable description of these bands by performing exact three-dimensional angular-momentum projection technique. The results obtained are also consistent with the global predictions of non-axial shapes for these isotopes. Besides this, the present study predicts the involvement of 2-quasiparticle neutron bands in describing various structural properties of these isotopes up to high spin states and has also achieved an excellent agreement of theoretical results with the known experimental data.

A systematic study of $\gamma$-bands observed in atomic nuclei is performed using the triaxial projected shell model (TPSM) approach. The staggering phase between the even and odd spin members of the $\gamma$-band for most the nuclei investigated in the present work is found to have even-I-below-odd-I, which in the framework of the collective model is considered as a signature of $\gamma$-softness. It is observed that out of twenty-three systems studied, only four nuclei, namely, $^{76}$Ge, $^{112}$Ru, $^{170}$Er and $^{232}$Th depict staggering phase with odd-I-below-even-I, which is regarded as an indication of the static $\gamma$-deformation in the collective model picture. The inclusion of the quasiparticle excitations in the framework of configuration mixing is shown to reverse the staggering phase from odd-I-down to the even-I-down for all the studied nuclei, except for the aforementioned four nuclei. Furthermore, by fitting a collective Bohr Hamiltonian to the TPSM energies, the differences between the two models are delineated through a comparison of the transition probabilities., Comment: 12 pages, 15 figures

The low-lying non-yrast states in $^{114}\mathrm{Te}$ have been investigated using the Indian National Gamma Array through the fusion-evaporation reaction $^{112}\mathrm{Sn}(^{4}\mathrm{He},2n)$ at a beam energy of 37 MeV. Eight new $\ensuremath{\gamma}$ transitions have been placed in the level scheme to establish the quasi-$\ensuremath{\gamma}$ band in this nucleus. Spin and parity of several excited states have been assigned from the present spectroscopy measurements. The comparison of experimental results on the observed bands with the interacting boson model (IBM) and triaxial projected shell model (TPSM) confirms the existence of the quasi-$\ensuremath{\gamma}$ band structure in the $^{114}\mathrm{Te}$ nucleus.

Aiming to understand the role of triaxiality and the evolution of the ground state nuclear shapes, we have carried out a microscopic study for a series of chains of Pd, Xe, Ba, Nd, Sm, Gd, and Dy isotopes. This is done within the self-consistent Relativistic-Hartree-Bogoliubov (RHB) formalism, and supported by the Triaxial Projected Shell Model (TPSM) approach. Pairing interaction separable in the momentum space with DD-ME2 force parameter is used to generate the potential energy surfaces(PESs) under the axial and triaxial symmetry. Shape evolution manifest themself in very clear manner in almost all the isotopic chains. Properties of the global mimima have been found to be in good agreement with the available experimental data. Relatively flat PESs, and $\gamma$-soft nature, have been suggested $^{108,110}$Pd, $^{132,134}$Xe and $^{134}$Ba as good candidates for E(5) symmetry, while $^{102}$Pd is not found suitable for E(5) symmetry. The PESs with a bump, and rigidity against triaxial variable($\gamma$) suggested $^{150}$Nd, $^{152}$Sm and $^{154}$Gd to be good candidates while $^{150}$Sm and $^{156}$Dy are poor candidates of X(5) critical-point symmetry. The findings of the present RHB calculations supported by TPSM are qualitatively in good agreement with the experimental and other theoretical calculations., Comment: accepted in Nucl. Phys. A

The negative parity bands in the odd-mass Palladium (Pd) nuclei in mass region A ∼110 are known to be built on the deformation-driving h 11 / 2 neutron orbital. They offer rich testing grounds for the present day models as well as provide good base to study the deformation systematics of this mass region along with the other nuclear structure properties. Motivated by this, we have taken up the study of odd-mass isotopic chain of 99−117Pd by applying the theoretical framework of the Projected Shell Model. The results are obtained for the negative parity yrast cascades in these nuclei as well as the on the reduced electric transition probabilities. The quasi-particle structure of these bands has been understood in terms of the band diagrams in which the rotational phenomenon like band-crossing is also discussed. The E-GOS plots along with the R2/1 and R3/2 ratios predict the quasi-deformed structure for these bands.

Theoretical investigation of positive parity yrast band of odd-odd 130Pr nucleus is performed by applying the projected shell model. The present study is undertaken to investigate and verify the very recently observed side band in 130Pr theoretically in terms of quasi-particle (qp) configuration. From the analysis of band diagram, the yrast as well as side band are found to arise from two-qp configuration πh 11/2 ⊗ νh 11/2. The present calculations are viewed to have qualitatively reproduced the known experimental data for yrast states, transition energies, and B(M1) / B(E2) ratios of this nucleus. The recently observed positive parity side band is also reproduced by the present calculations. The energy states of the side band are predicted up to spin 25+, which is far above the known experimental spin of 18+ and this could serve as a motivational factor for future experiments. In addition, the reduced transition probability B(E2) for interband transitions has also been calculated for the first time in projected shell model, which would serve as an encouragement for other research groups in the future.

The basis space in the triaxial projected shell model (TPSM) approach is generalized for odd-odd nuclei to include two-neutron and two-proton configurations on the basic one-neutron coupled to one-proton quasiparticle state. The generalization allows to investigate odd-odd nuclei beyond the band crossing region and as a first application of this development, high-spin band structures recently observed in odd-odd $^{194-200}$Tl isotopes are investigated. In some of these isotopes, the doublet band structures observed after the band crossing have been conjectured to arise from the spontaneous breaking of the chiral symmetry. The driving configuration of the chiral symmetry in these odd-odd isotopes is one-proton and three-neutrons rather than the basic one-proton and one-neutron as already observed in many other nuclei. It is demonstrated using the TPSM approach that energy differences of the doublet bands in $^{194}$Tl and $^{198}$Tl are, indeed, small. However, the differences in the calculated transition probabilities are somewhat larger than what is expected in the chiral symmetry limit. Experimental data on the transition probabilities is needed to shed light on the chiral nature of the doublet bands., Comment: 11 pages, 17 figures, to appear in EPJA

Lifetimes of excited states of the ground-state rotational band in the $^{136}\mathrm{Sm}$ nucleus have been measured up to ${I}^{\ensuremath{\pi}}={20}^{+}$ using the Doppler-shift attenuation method. The states were populated in the reaction $^{107}\mathrm{Ag}$($^{32}\mathrm{S}$, $1p2n$) at 145-MeV beam energy and the $\ensuremath{\gamma}$ rays emitted from the excited states were detected using the Indian National Gamma Array at the Tata Institute of Fundamental Research, Mumbai. The extracted transitional quadrupole moments indicate a reduction of collectivity with increasing spin after the band crossing. The results have been compared with the predictions of the cranked shell model as well as the triaxial projected shell-model calculations and indicate that the nucleus evolves from prolate $\ensuremath{\gamma}$-soft to a stable triaxially deformed shape after the first and the second crossing involving $\ensuremath{\pi}{h}_{11/2}^{2}$ and $\ensuremath{\pi}{h}_{11/2}^{2}\ensuremath{\bigotimes}\ensuremath{\nu}{h}_{11/2}^{2}$ configurations, respectively.

Excited states of 124Te have been studied via 122Sn(9Be,$ \alpha$3n)124Te reaction at 48MeV. The spin and parity of several states have been confirmed on the basis of results of angular correlation ( $ R_{DCO}$ and linear polarization asymmetry measurements. The positive parity band structures of 124Te and 126Te have been investigated and the quasi-$ \gamma$ bands have been proposed in these nuclei. The structures of these bands have also been discussed under the framework of triaxial projected shell model (TPSM) calculations. The TPSM calculations fairly supported the interpretation of quasi-$ \gamma$ bands in 124Te and 126Te. The staggering pattern of odd-even spin states of the quasi-$ \gamma$ band suggests the $ \gamma$-soft behaviour of 124Te and the typical values of staggering factors indicate the presence of the E(5)-critical point symmetry in 124Te. The potential energy surface calculations have also been carried out for 124Te and 126Te, which also supports the $ \gamma$-soft behaviour for these nuclei.

Low lying states of 198Hg have been investigated via 197Au(7Li,$\alpha$2n$\gamma$) reaction at $ E_{\mathrm{beam}} = 33, 38$ MeV and the members of the $\gamma$-vibrational band have been identified. Results are compared with the systematic of this mass region and found in agreement. The observed band structures have been interpreted using the theoretical framework of the microscopic triaxial projected shell model (TPSM) approach and it is shown that TPSM results are in fair agreement with the observed energies.

By using the phenomenological approach of Projected Shell Model (PSM), the positive and negative-parity band structures of odd mass neutron-rich 119–127 I nuclei have been studied with the deformed single-particle states generated by the standard Nilsson potential. For these isotopes, the band structures have been analyzed in terms of quasi-particles configurations. The phenomenon of backbending in moment of inertia is also studied in the present work. Besides this, the reduced transition probabilities, i.e. B ( E 2 ) and B ( M 1 ) , are obtained from the PSM wavefunction for the first time for yrast bands of these isotopes.

Band structures of the neutron-rich Mo- and Ru-isotopes around A $\sim $ 110 are investigated using the triaxial projected shell model (TPSM) approach employing multi-quasiparticle configuration space. The mass region under investigation depicts a rich variety of band structures with well developed $\gamma$- and $\gamma\gamma$-bands, and quasiparticle excitations based on them. It is demonstrated that TPSM provides a reasonable description of most of the observed properties, in particular, detailed structure variations observed in Mo-isotopes are well reproduced in the present work., Comment: 19 pages, 7 figures, to appear in Nucl. Phys. A

Inspired by the availability of recent experimental as well as theoretical data on the energy levels of odd-mass 151-161Pm and odd-odd 154,156Pm, we applied the theoretical framework of the projected shell model to further understand the nuclear structure of these nuclei. The calculations closely reproduced the experimental data reported for the yrast bands of these isotopes by assuming an axial (prolate) deformation of ~0.3. Other properties along the yrast line, such as transition energies and transition probabilities, have also been discussed. Band diagrams are plotted to understand their intrinsic multi-quasiparticle structure, which turn out to be dominated by 1-quasiparticle bands for the odd-mass Pm isotopes and 2-quasiparticle bands for the doubly-odd Pm isotopes under study. The present study not only confirms the recently reported experimental/theoretical data, but also extends the already available information on the energy levels and adds new information regarding the reduced transition probabilities.

In this study, the multi-quasiparticle triaxial projected shell model (TPSM) is applied to investigate -vibrational bands in transitional nuclei of . We report that each triaxial intrinsic state has a -band built on it. The TPSM approach is evaluated by the comparison of TPSM results with available experimental data, which shows a satisfactory agreement. The energy ratios, B(E2) transition rates, and signature splitting of the -vibrational band are calculated.

The present work focuses on the successful application of the Projected Shell Model (PSM) in studying the yrast bands of neutron-rich odd-mass 111-119In nuclei. For these isotopes, the band structures have been analyzed in terms of quasi-particles configurations. The phenomenon of rotational alignment and back bending in moment of inertia is also studied in the present work. The intrinsic structure of 111-119In nuclei in the present study has also been described as arising due to an interplay between proton and neutron orbitals belonging to 1- and 3-qp configurations. Besides this, the reduced transition probabilities, B(E2) and B(M1) , are also obtained from the PSM wave functions.

Projected Shell Model calculations have been employed for the description of the ground band in odd mass 57–67Co isotopes. In the present work, quadrupole and monopole pairing interactions as well as quadrupole–quadrupole interactions are effectively included in the Hamiltonian for obtaining various nuclear structure properties using the angular momentum projection technique. The yrast spectra of these isotopes are described as interplay between the angular momentum projected states around the Fermi level. The quasi-particle structure of these nuclei is found to be comprised of different intrinsic K-quantum numbers. Rotational alignments in terms of kinetic moment of inertia ( ℑ ( 1 ) ) have also been discussed. The electromagnetic transition probabilities [ B ( E2 ) and B ( M1 ) ] are also obtained in the present work and are found to be in good agreement with the available experimental as well as the other theoretical data, which tests the consistency of the applied projected shell model. The present PSM calculations also report the existence of low lying deformed structure along with the spherical structure at N = 40 .

Excited band structures recently observed in $^{156}\mathrm{Dy}$ are investigated using the microscopic triaxial projected shell model (TPSM) approach and the quasiparticle random phase approximation (QRPA) based on the rotating mean field. It is demonstrated that new observed excited bands, tracking the ground-state band, are the $\ensuremath{\gamma}$ bands based on the excited two-quasineutron configurations as conjectured in the experimental work.

A systematic study of the doublet bands observed in odd–odd mass ∼100 is performed using the microscopic triaxial projected shell model approach. This mass region has depicted some novel features which are not observed in other mass regions, for instance, it has been observed that doublet bands cross diabatically in 106 Ag. It is demonstrated that this unique feature is due to crossing of the two 2-quasiparticle configurations having different intrinsic structures. Further, we provide a complete set of transition probabilities for all the six-isotopes studied in this work and it is shown that the predicted transitions are in good agreement with the available experimental data.

The positive and negative parity rotational band structure of the neutron rich odd mass Eu isotopes with neutron numbers ranging from 90 to 96 are investigated up to the high angular momentum. In the theoretical analysis of energy spectra, transition energies and electromagnetic transition probabilities we employ the projected shell model. The calculations successfully describe the formation of the ground and excited band structures from the single particle and multi quasiparticle configurations. Calculated excitation energy spectra, transition energies, exact quantum mechanically calculated B(E2) and B(M1) transition probabilities are compared with experimental data wherever available and a reasonably good agreement is obtained with the observed data. The change in deformation in the ground state band with the increase in angular momentum and the increase in neutron number has also been established.

A systematic study of the yrast band structure for the neutron-rich odd-mass 103-111Tc nuclei is carried out using Projected Shell Model. The rotational band structure has been studied up to a maximum spin of $ 59/2^{+}$ . Excellent agreement with available experimental data for all isotopes is obtained. The energy spectra and electromagnetic transition strengths in terms of the configuration mixing of the angular-momentum projected multi-quasiparticle states are studied in detail. Signature splitting in the yrast rotational band is well described in the perspective of nuclear structure physics. The back-bending phenomenon is also well described for these nuclei in the present work.

The band structures of $^{68,70}$Ge, $^{128,130,132,134}$Ce and $^{132,134,136,138}$Nd are investigated using the triaxial projected shell model (TPSM) approach. These nuclei depict forking of the ground-state band into several s-bands and in some cases, both the lowest two observed s-bands depict neutron or proton character. It was discussed in our earlier work that this anamoluos behaviour can be explained by considering $\gamma$-bands based on two-quasiparticle configurations. As the parent band and the $\gamma$-band built on it have the same intrinsic structure, g-factors of the two bands are expected to be similar. In the present work, we have undertaken a detailed investigation of g-factors for the excited band structures of the studied nuclei and the available data for a few high-spin states are shown to be in fair agreement with the predicted values., Comment: 29 pages, 20 figures. Nucl. Phys. A (2017)

Excited states in the $^{101}\mathrm{Pd}$ nucleus were investigated through the $^{75}\mathrm{As}(^{31}\mathrm{P},2p3n)$ fusion-evaporation reaction at ${E}_{\mathrm{lab}}=125$ MeV by using the Indian National Gamma Array spectrometer equipped with 21 clover Ge detectors. The level scheme is considerably extended for medium spin values. New positive-parity band structures in $^{101}\mathrm{Pd}$ have been studied within the framework of the projected shell model and are found to undergo transition from single quasiparticle to high-$K$ three quasiparticle configuration after band crossing, i.e., from principal-axis rotation to tilted-axis rotation. The negative-parity band structures are discussed in the framework of the hybrid version of tilted-axis cranking shell model calculations. The observed alignment gain in the lowest excited $\ensuremath{\nu}{h}_{11/2}$ negative-parity band results from successive ${(\ensuremath{\nu}{g}_{7/2})}^{2}$ and ${(\ensuremath{\pi}{g}_{9/2})}^{2}$ pair alignments. The higher excited negative-parity bands are reproduced for the $\ensuremath{\nu}[{h}_{11/2}{({g}_{7/2}/{d}_{5/2})}^{2}]$ and ${(\ensuremath{\pi}{g}_{9/2})}^{\ensuremath{-}2}\ensuremath{\bigotimes}\ensuremath{\nu}{h}_{11/2}$ configurations.

Rotational spectra of odd-odd Rh and Ag isotopes are investigated with the primary motivation to search for the spontaneous chiral symmetry breaking phenomenon in these nuclei. The experimental results obtained on the degenerate dipole bands of some of these isotopes using a large array of gamma detectors are discussed and studied using the triaxial projected shell (TPSM) approach. It is shown that, first of all, to reproduce the odd-even staggering of the known yrast bands of these nuclei, large triaxial deformation is needed. This large triaxial deformation also gives rise to doublet band structures in many of these studied nuclei. The observed doublet bands in these isotopes are shown to be reproduced reasonably well by the TPSM calculations. Further, the TPSM calculations for neutron-rich nuclei indicate that the ideal manifestation of the chirality can be realised in 106Rh and 112Ag , where the doublet bands have similar electromagnetic properties along with small differences in excitation energies.

Doublet bands observed in $^{124,126,130,132}$Cs isotopes are studied using the recently developed multi-quasiparticle microscopic triaxial projected shell model (TPSM) approach. It is shown that TPSM results for energies and transition probabilities are in good agreement with known energies and the recently measured extensive data on transition probabilities for the bands in $^{126}$Cs. In particular, it is demonstrated that characteristics transition probabilities expected for the doublet bands to originate from the chiral symmetry breaking are well reproduced in the present work. The calculated energies for $^{124,130,132}$Cs are also shown to be in reasonable agreement with the available experimental data. Furthermore, a complete set of the calculated transition probabilities is provided for the doublet bands in $^{124,130,132}$Cs isotopes., Comment: 14 pages, 9 Figures, Accepted in Nuclear Physics A

A microscopic high spin study of neutron deficient and normally deformed 133,135,137Sm has been carried out in projected shell model framework. The theoretical results have been obtained for the spins, parities and energy values of yrast and excited bands. Besides this, the band spectra, band head energies, moment of inertia and electromagnetic transition strengths are also predicted in these isotopes. The calculations successfully give a deeper understanding of the mechanism of the formation of yrast and excited bands from the single and multi-quasi particle configurations. The results on moment of inertia predict an alignment of a pair of protons in the proton (1h 11/2)2 orbitals in the yrast ground state bands of 133-137Sm due to the crossing of one quasiparticle bands by multi-quasiparticle bands at higher spins. The discussion in the present work is based on the deformed single particle scheme. Any future experimental confirmation or refutation of our predictions will be a valuable information which can help to understand the deformed single particle structure in these odd mass neutron deficient 133-137Sm.