[en] Several dipole bands based on three quasiparticle configurations were reported in A ∼140 mass region. In odd-neutron ¹³⁹Nd (Z=60) and ¹³⁷Sm (Z=62) nuclei, a positive parity dipole band, based on πh_11/2 ⊗ πg_7/2 ⊗ νh_11/2 3-qp configuration was reported at relatively lower excitation energy (2 MeV), as compared to negative parity dipole bands. The observation of such bands are very rare in this mass region. A similar band was observed in odd-proton ¹³⁹Pm (Z = 61), the parity of the band was not confirmed. Present work confirmed the parity of this band on the basis of linear polarization measurement. The work extends the systematic of the rare band from odd-neutron to odd-proton nuclei and provide additional information on the band structure

[en] In the present work, ¹³⁹Pm, an odd proton nucleus in the mass region A∼ 130 is studied to investigate the nuclear shape behaviour up to well above the backbendings

[en] In the present work, ¹³⁹Pm, an odd-proton nucleus in the mass region A∼139 is studied to high spin and excitation energy

[en] In-beam γ-ray spectroscopy serves as an efficient tool to investigate structural properties of nuclei. The present thesis provides a γ-ray spectroscopic investigation of band structures of transitional nuclei near proton shell closure (Z = 50) and also near neutron shell closure (N = 82). Investigation of these nuclei draws great attention over last few decades due to the abundance of versatile structural phenomena and made a very good laboratory to test different theoretical models. The process helps to understand the various underlying physical processes for the shape evolution and phase transition processes in a many-body quantum system. In the present investigation, search for the states associated with the wobbling excitation, in ¹³⁹Pm, has also been carried out

[en] Unhindered 11/2^- → 11/2^-β-ray transitions with logft values of 5.0 to 5.4 have been observed in the decay of ¹³⁹Eu, ¹³⁹Sm/subm/, and a new isotope ¹³⁵Pm. These transitions show no noticeable retardation and are not ''shape forbidden.'' The shape of 11/2^- states with odd N is not very different from the (prolate) shape of adjacent 11/2^- states with odd Z

No abstract available

[en] Magnetic-dipole rotational (MR) bands were discovered about 15 years ago, and have been explained using shears mechanism. The theoretical understanding of these bands has been provided using tilted axis cranking (TAC). At present, magnetic rotation has been seen in whole nuclear landscape and about 180 bands in 80 nuclides has been observed in mass regions A=20, 60, 80, 110, 135 and 195 respectively. The crossing of these bands (ΔI = 1) is very much similar to normal band crossing (ΔI = 2) and already exhibited in different mass regions. We have observed new MR bands and their crossing in the A = 130 mass region in ¹³⁵La, ¹³⁷Pr and ¹³⁹Pm nuclei. The systematic evolution of this phenomenon in N=78 odd-Z isotones leads us to understand the role on nucleons in this crossing.

[en] The excited states of ¹³⁹Pm is investigated via ¹²⁷I(¹⁶O, 4n)¹³⁹Pm reaction at 84 MeV beam energy. The spin and parity of several states have been determined from the results of angular correlation (R_DCO) and linear polarization asymmetry (${\mathrm{\Delta <!--\; ??\; -->}}_{asym}$) measurements. The features of four positive parity bands have been determined. A band above $17/2^{+}$ state at 1951 keV comprised of strong magnetic dipole transitions has been established and a three-quasi-protons configuration is suggested on the basis of systematic of neighbouring nuclei. Additionally, a new band above $7/2^{+}$ state at 228 keV is observed. The states are compared with the modified particle rotor model calculations which indicated πg _7/2 configuration for this band. (paper)

[en] The structure of ¹³⁹Pm is investigated through the β⁺ decay of ¹³⁹Sm/sup g/, whose decay half-life is measured to be 2.57 +- 0.10 min. A level scheme comprising 33 excited states and all the observed 79 transitions is constructed based on information obtained from γ ray, β⁺, and internal conversion electron spectroscopic measurements. Using the deduced beta decay logft values and transition multipolarities, J/sup π/ assignments are made to states in ¹³⁹Pm and to the ground state of ¹³⁹Sm. The β⁺ end-point energy measurements give a total decay energy Q/sub EC/ = 4.10 +- 0.15 MeV for ¹³⁹Sm/sup g/. Systematics of low-lying states in the odd-A, N = 78 isotones are discussed

[en] High-spin states in nucleus ¹³⁹Pm have been studied using the reaction ¹¹⁶Cd(²⁷Al, 4n)¹³⁹Pm. Two dipole cascades have been found. Spin and parity assignments were based on the Directional Correlation of Oriented Nuclei(DCO) ratios and systematic behavior in neighboring odd-proton nuclei. The level structures of ¹³⁹Pm are compared with those of the N =78 isotope ¹⁴¹Eu in which two dipole bands have been confirmed as magnetic rotational bands. The close similarity between them suggests that the dipole bands in ¹³⁹Pm may be magnetic rotational bands. (authors)