M. Kumar Raju

Transverse Wobbling in

A pair of transverse wobbling bands is observed in the nucleus ^{135}Pr. The wobbling is characterized by ΔI=1, E2 transitions between the bands, and a decrease in the wobbling energy confirms its transverse nature. Additionally, a transition from transverse wobbling to a three-quasiparticle band comprised of strong magnetic dipole transitions is observed. These observations conform well to results from calculations with the tilted axis cranking model and the quasiparticle rotor model.

^{135}

The structure of

Pr

^{70}

Observation of aγband based on a two-quasiparticle configuration inGe70

Ge has been studied through in-beam gamma ray spectroscopy. A new band structure is identified that leads to forking of the ground-state band into two excited bands. Band structures have been investigated using the microscopic triaxial projected shell model approach. The observed forking is demonstrated to result from almost simultaneous band crossing of the two neutron aligned and the \gamma-band built on this two-quasiparticle configuration with the ground-state band.

Energy levels in 141Nd from fusion evaporation study

The nucleus 141Nd has been investigated using two different heavy ion fusion evaporation reactions, namely 130Te(16O, 5n) at Elab = 80–85 MeV and 124Sn(24Mg,α3n) at Elab = 107 MeV, and the de-exciting gamma rays were detected using HPGe(GDA) and Clover detector (INGA) arrays, respectively. More than 30 new gamma transitions have been placed in the proposed level scheme, which has been extended up to 9 MeV excitation energy and spin parity values of 45/2−. Spin parity assignments have been made to most of the newly proposed levels. The structure up to approximately 6 MeV excitation energy and spin 31/2− can be explained using the shell model in a truncated basis. The levels with higher spin/energy cannot be described using even the full 50–82 shell, indicating the influence of neutron excitations across the shell gap in this mass region. One M1 band that has been observed is proposed to have a five quasiparticle configuration.

Abrupt phase change of the core rotation in the 143 Sm nucleus

Abstract Dipole sequences in the 143 Sm nucleus have been investigated via the 124 Sn ( 24 Mg, 5n) reaction at E l a b = 107 MeV using the Indian National Gamma Array (INGA). The spin-parity of the associated levels have been firmly established from the spectroscopic measurement. Level lifetimes of several levels in the dipole bands have been measured using the Doppler Shift Attenuation Method. The decreasing trend of the measured B ( M 1 ) and B ( E 2 ) transition strengths in one of the sequence (DB I) spells out its origin as Magnetic Rotation (MR). Though, the trends of B ( M 1 ) and B ( E 2 ) in DB I are reproduced well in the theoretical calculations using the Shears mechanism with the Principal Axis Cranking (SPAC) model, the calculations fail to reproduce the sharp rise in the B ( M 1 ) / B ( E 2 ) ratio at the highest spins in DB I. Such rise in the B ( M 1 ) / B ( E 2 ) values is in well agreement with the theoretical calculations within the shears mechanism as prescribed by the Clark and Macchiavelli considering the smooth decrease of the core rotation along the sequence. The experimental observations along with the theoretical calculations for the second dipole band (DB II), indicate that the core rotation, rather than the shears mechanism, is being favored for angular momentum generation. This represents a unique observation of forking of the shears band DB I from an abrupt phase change of the core from spherical into the deformed one.

Investigation of chirality in the case of 102Rh

Excited states in 102Rh were populated in the fusion-evaporation reaction 94Zr(11B, 3n)102Rh at a beam energy of 36 MeV using the INGA spectrometer at IUAC, New Delhi. The angular correlations and the electromagnetic character of some of the gamma-ray transitions observed were investigated in details. A new chiral candidate sister band was found. Lifetimes of exited states in 102Rh were measured using the Doppler-shift attenuation technique and the derived reduced transition probabilities are compared to the predictions of the Two Quasiparticles Plus Triaxial Rotor model.

High Spin Spectroscopy and Shape Evolution in 105 Cd

High spin states in 105Cd were studied using 16O beam on 92Mo reaction at an incident beam energy of 75 MeV. The level scheme of 105Cd has been observed up to an excitation energy of 10.8 MeV with the addition of 30 new gamma transitions to the previous work. Spin and parity for most of the reported levels are assigned from the DCO ratios and linear polarization measurements. The microscopic origin of the investigated band structures is discussed in the context of triaxial projected shell model. The energies of observed positive and negative parity bands agree with the predictions of the TPSM by considering triaxial deformation for the observed excited band structures. The shape evolution with increasing angular momentum is explained in the framework of Cranked Shell Model and the Total Routhian Surface calculations.

In a search for a chiral symmetry in 102Rh

Excited states in 102Rh were populated in the fusion-evaporation reaction 94Zr(nB, 3n)102Rh at a beam energy of 36 MeV, using the INGA spectrometer at IUAC, New Delhi. The angular correlations and the electromagnetic character of some of the ?-ray transitions observed in 102Rh were investigated in detail. A new candidate for a chiral twin band was identified in 102Rh for the first time.

Check for chirality in 102Rh

Excited states in 102Rh, populated by the fusion-evaporation reaction 94Zr(11B,3n)102Rh at a beam energy of 36 MeV, were studied using the INGA spectrometer at IUAC, New Delhi. The angular correlations and the electromagnetic character of some of the gamma-ray transitions observed were investigated in details. A new chiral candidate sister band was found in the level-scheme of 102Rh. Lifetimes of exited states in 102Rh were measured by means of the Doppler-shift attenuation technique. The experimental results do not support the presence of static chirality in 102Rh.