S. Muralithar

Systematics of antimagnetic rotation in even–even Cd isotopes

Abstract A model based on classical particle plus rotor has been used to explore the underlying systematics of even–even Cd isotopes and a self consistent picture for the observed behaviors of 106, 108, 110 Cd has been reported. This systematic study also helps to estimate the strengths of particle–hole and hole–hole interactions of this mass region.

Spectroscopy of Nuclei Approaching the Proton Drip-line Using a Secondary-fragmentation Technique with the RISING Detector Array

An experiment utilizing a double fragmentation reaction was performed to study isobaric analogue states in A similar to 50 nuclei approaching the proton drip-line. gamma-ray spectroscopy will be used to identify excited states in the neutron-deficient nuclei produced in the second fragmentation reaction. Excited state level schemes will be obtained, through comparison with states in their well-known mirror partners, along with information on Coulomb effects through measurements of the Coulomb energy differences between isobaric analogue excited states. The validity of isospin symmetry for nuclei approaching the proton drip-line can also be investigated and the information gained will aid in testing and improving fp shell model calculations. The analysis of the collected data is at a preliminary stage and current status of this work is reported.

Band crossing in a shears band of Cd 108

The level lifetimes have been measured for a Shears band of 108 Cd which exhibits bandcrossing. The observed level energies and B(M1) rates have been successfully described by a semi-classical geometric model based on shear mechanism. In this geometric model, the bandcrossing in Shears

Structure of positive-parity yrast band in 80 Br

Abstract The states of the positive-parity yrast band in 80 Br have been investigated using the 76 Ge( 7 Li, 3n γ ) reaction at a beam energy of 32 MeV. The band has been extended up to 4450 keV with a spin of (14 + ). Unambiguous spin assignments are made for states up to 2944.0 keV and γ -ray multipole mixing ratios are determined for several ΔJ=1 transitions. Lifetimes studies for the 10 + , 11 + and 12 + states provide an estimate of the quadrupole deformation in this band. Cranking model analysis of the experimental data reveals a signature inversion at a spin of 12 ℏ and a probable neutron alignment at ℏω≈0.7 MeV. The results are discussed within the framework of the systematics of similar bands in the lighter Br isotopes and the cranked-shell model. In addition, a new positive-parity and two negative-parity sequences have been identified.

Alignments and new band structures in the doubly odd nucleus 80Rb

Abstract The high spin structure of 80Rb has been investigated using the reaction 51V(32S,2pn) at a beam energy 105 MeV. The level scheme was established from γ-γ and recoil-γ-γ coincidence measurements obtained using the Gamma Detector Array consisting of eight Compton suppressed Ge detectors coupled to the recoil mass separator HIRA. Rotational states upto an excitation energy 13 MeV and a spin 25ħ were studied. Band crossings at ħω = 0.63 and 0.73 MeV in the negative parity band, due to successive g 9 2 proton and neutron alignment, were observed for the first time. Evidence has also been found for a hitherto unknown sideband. The yrast positive parity bands in 78Kr and 80Rb have similar transition energies beyond a rotational frequency ħω ≈ 0.55 MeV. This is the only known example of identical bands in nuclei differing by two quasiparticles, in this mass region.

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.

High-spin structures in 112Sb

Abstract A spectroscopic study of 112Sb has been carried out using the 103Rh(12C,3n) reaction. The low energy excited levels are interpreted in terms of two-quasiparticle configurations arising from the proton and neutron motion in the πg 7 2 , πd 5 2 , νg 7 2 , νd 5 2 and νh 11 2 shell model orbitals. A strongly coupled rotational band, most likely based on a deformed πg 9 2 −1 πg 7 2 2 ⊗ νh 11 2 configuration, is identified at somewhat higher excitation energy. The B( M 1) B( E 2) ratios for some of the transitions in the strongly coupled band indicate mixed nature of the intrinsic configuration.

Indian National Gamma Array at IUAC

Indian National Gamma Array (INGA) is a 4π multi-detector gamma-ray spectrometer based on twenty four Compton-suppressed Clover Germanium detectors with a total photo peak efficiency ~ 5 %. INGA was designed to perform high resolution gamma-ray spectroscopy to study nuclear structure at high spins with stable ion beams at Inter University Accelerator Centre (IUAC). Description of the facility and performance of the array are presented in this paper. Since its commissioning, a number of nuclear spectroscopic investigations have been carried out using the array.

Relativistic coulomb excitation of neutron-rich 54,56,58Cr

The first excited 2+ states in neutron-rich 54,56,58Cr were populated by relativistic Coulomb excitation and B (E2, 2 1 + → 0+) values were determined for 56Cr and 58Cr. The B(E2) values show a minimum for 56Cr providing evidence for a subshell closure at N=32.

High spin states in102Ag

High spin states are populated in102Ag using the reaction16O+89Y with projectile energies in the energy range 60–80 MeV. Gamma multipolarities are inferred from DCO ratios and coincidence relationships are established among the gamma rays assigned to102Ag. A comprehensive level scheme is constructed with four band systems, two of positive parity and the other two of negative parity. The present study extended spins upto 19− in the main negative parity band. A new band is populated in the present work and is similar to the one observed in106Ag.