Yogendra Gambhir

Yogendra Gambhir
Manipal Academy of Higher Education | MAHE

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155
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Publications

Publications (155)
Article
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After publication of the paper, the authors noticed some errors in the affiliations. Their correct version is given in this erratum.
Article
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The results for nuclei above curium, produced in multi-nucleon transfer reactions of ⁴⁸Ca + ²⁴⁸Cm at the velocity filter SHIP of GSI Darmstadt, are presented. Spontaneous fission and \( \alpha\)-activities have been used to study the population of nuclei with lifetimes ranging from few milliseconds to several days. We observed several, relatively n...
Article
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Microscopic investigations for the observed properties of the recently reported five unstable new isotopes are carried out. The ground state properties are calculated in the relativistic mean field (RMF) framework and the results reproduce the experiment well as expected. The α-decay lifetimes are calculated in the double folding model using WKB ap...
Article
Full-text available
Microscopic investigations for the observed properties of the recently reported five unstable new isotopes are carried out. The ground state properties are calculated in the relativistic mean field (RMF) framework and the results reproduce the experiment well as expected. The {\alpha} - decay lifetimes are calculated in the double folding model usi...
Article
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Systematic calculations of superheavy region from Z = 100 to Z = 150 and N/Z ratio ranging from 1.19 to 2.70 have been carried out within the framework of the Relativistic Hartree-Bogolyubov model. It has been shown that the possible upper limit on the periodic table could be Z = 146, which is at variance with predictions of sophisticated atomic ma...
Article
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A systematic analysis of hot fusion reactions with a comparison to experimental cross sections related to the synthesis of superheavy elements is carried out using the hivap code. A single parameter set is found which when implemented in the hivap computer code, describes experimental production cross sections for reactions using a Ca48 beam on act...
Article
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The problem of finding the highest limiting Z in the extended periodic table is discussed. The upper limit suggested by the atomic many body theory at Z=172 may be reached much earlier due to nuclear instabilities. Therefore, an extensive set of calculations based on the relativistic mean field formulation are carried out for the ground state pro...
Article
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In deep inelastic multinucleon transfer reactions of 48Ca + 248Cm we observed about 100 residual nuclei with proton numbers between Z=82 and Z=100. Among them, there are five new neutron-deficient isotopes: 216U, 219Np, 223Am, 229Am and 233Bk. As separator for the transfer products we used the velocity filter SHIP of GSI while the isotope identific...
Article
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The question of a possible limit for the existence of the chemical elements is discussed in the context of recent findings in the fields of nuclear and atomic physics and chemistry. At the time of this writing, there is no evidence to support the occurrence of the heaviest elements in Nature. The upper end of the Periodic Table has been reached onl...
Article
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The results of fully microscopic calculations for the α-decay half-lives of light α emitters close to the N=Z line are presented. The ground-state properties are calculated in the relativistic mean field (RMF) approach which reproduce the experiment well, as expected. The α-daughter nucleus potential is then calculated in the double folding model u...
Article
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Recently themeasured proton-9Celastic angular distribution at 300MeV/nucleon had been analyzed within the Brueckner-Hartree-Fock framework. The Argonne v-18 internucleon potential was used to generate the reaction matrices which were then folded over 9C density distributions obtained by using the relativistic mean-field model. The calculations yiel...
Article
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The proton - nucleus optical potentials generated by folding the calculated complex, density and energy dependent g- matrices (with and without three-body forces (TBF): Urbana IX (UVIX) and TNI) over the target nucleon density distributions obtained from the relativistic mean field theory, are used for the calculation of the differential cross sect...
Article
Angular-momentum- and number-projected Hartree-Fock-Bogoliubov (HFB) wave functions of translational and deformed rare earth nuclei are analyzed in terms of fermion pairs coupled to angular momenta L = 0 (S), 2 (D), 4 (G),/3. The fermion space is truncated to contain only S-D or S-D-G pairs. The variation is carried out before and after angular mom...
Article
A microscopic proton–nucleus optical potential is calculated for all even isotopes 52–112Ni within the Brueckner–Hartee–Fock framework. The reaction matrices calculated using three (Argonne v18, Reid93 and NijmII) realistic inter-nucleon potentials with and without three-body forces (Urbana IX (UVIX) and the density dependent three-nucleon interact...
Article
The excitation energy difference (ΔE) between the terminating states built on the f7/2n and d3/2-1f7/2n+1 configurations (here, 'n' denotes the number of valence particles outside the 40Ca core and the particle hole excitation across the magic gap 20 is of proton type) in the lower fp shell are studied systematically within the framework of the cra...
Article
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We report microscopic calculations of the equation of state of symmetric nuclear matter and the nucleon-nucleus optical potential in the Brueckner-Hartree-Fock approach. The calculations use several internucleon (NN) potentials, such as the Hamada-Johnston, Urbana v14, Argonne v14, Argonne v18, Reid93, and Nijm II along with and without two types o...
Article
Proton-nucleus scattering provides a useful tool to determine either the parameters entering in the assumed shape of the neutron distribution or to test the reliability of the theoretically calculated neutron distributions in the target nuclei. We have used the Bethe-Brueckner-Hartree-Fock approach to calculate the optical potential for analyzing t...
Article
Systematic investigations of the pairing and two-neutron separation energies which play a crucial role in the evolution of shell structure in nuclei, are carried out within the framework of relativistic mean-field model. The shell closures are found to be robust, as expected, up to the lead region. New shell closures appear in low mass region. In t...
Article
The ground state nucleon (neutron and proton) distributions for A=20 isobars (Z=6–12) are investigated. For this purpose, the relativistic mean field equations are solved in the coordinate space and also by using the conventional basis expansion method. The pairing is treated in the simple constant gap approximation and also self consistently throu...
Article
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The Q-values and half-lives of several heavy α decaying systems are calculated using the relativistic mean field (RMF) theory-based microscopic α-daughter nucleus potential. A unified procedure is adopted, using analytic S-matrix method and treating α-decay as the decay of the resonance state of the α-daughter nucleus system. The resonance paramete...
Article
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A comparative study of the S-matrix and the WKB methods for the calculation of the half widths of alpha decay of super heavy elements is presented. The extent of the reliability of the WKB methods is demonstrated through simple illustrative examples. Detailed calculations have been carried out using the microscopic alpha-daughter potentials generat...
Article
An expression for nuclear anapole moment is derived within a valence nucleon relativistic mean-field nuclear model. The anapole moment parameter values are calculated for 133Cs, 85Rb, and 209Bi nuclei. The result reproduces the observed difference between hyperfine E1 transition amplitudes in 133Cs within the experimental accuracy. The change in th...
Article
The α-staggering for the nuclei in the 2p−1f region is investigated in the relativistic mean field approach. The observed behavior similar to the well known odd-even staggering is well reproduced. The decomposition of densities for these nuclei shows almost identical characteristics beyond the rms radii indicating that the alpha cluster, if exists,...
Article
Microscopic analysis of the recently reported 295-MeV-proton scattering data from Pb isotopes and 58Ni is presented within the framework of the Brueckner-Hartree-Fock theory. The effective interaction (g matrix) has been calculated using three Hamiltonians with Urbana v-14, Argonne v-18, and Ried93 internucleon potentials. The microscopic optical p...
Article
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The recently measured reaction cross sections for the neutron-rich carbon isotopes (¹C, ²°C, and ²²C) on a proton target at 40 A MeV are analyzed using the finite range Glauber model (FRGM) and the microscopic optical potential calculated within the Brueckner-Hartree-Fock formalism (BHF). In FRGM nucleon-nucleon cross sections are used, while in th...
Article
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We present a Brueckner theory analysis of proton-scattering data from Sn isotopes at 295 MeV. A soft-core Urbana v14 internucleon potential has been used to calculate reaction matrices that are folded with point-nucleon (both proton and neutron) densities obtained in the relativistic mean field (RMF) framework to calculate the optical potential. We...
Article
Most of the decaying systems namely alpha-decay and proton radio activity have extremely narrow widths and hence are termed as quasi-bound states. There are three methods available for the computation of very narrow widths. First, the analytic S-matrix method which treats resonance as a pole in complex energy plane with its real part representing r...
Article
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The fully microscopic p-nucleus optical potential has been calculated in the framework of the first order Brueckner theory employing Urbana V14, soft-core internucleon interaction along with the relativistic mean field densities both for protons and neutrons. It is observed that the volume integral per nucleon, of the real part of the spin-orbit in...
Article
Superheavy Elements (SHE) up to Z = 118 have been produced and studied. The Relativistic Mean Field (RMF) theory provides a reasonably good description of the ground state properties (binding energies, Q-values, deformation, radii, densities etc.) of these elements. Shell closures revealed by the vanishing/ minimum pairing energy, are predicted for...
Article
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Based on the detailed analysis of the reaction cross sections obtained using the finite range Glauber model, a systematic study of strong absorption radii is carried out. A simple phenomenological expression is proposed to calculate reaction cross sections directly using the average nucleon–nucleon cross section for a given target–projectile combin...
Conference Paper
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One of the most important current research activity in Nuclear Physics is the production and study of the superheavy elements (SHE). The elements upto Z = 118 have been produced and studied. After about four decades of experimentation, it still does not seem to be possible to reach the predicted [1, 2] Z = 114, N = 184 closed shell with stable neut...
Article
The α-nucleus fusion cross sections at energies around and below the barrier and the α-decay half lives are calculated in the semi-classical WKB approach using the same microscopic as well as empirical α-nucleus potentials. The microscopic potential is generated within the double-folding framework using M3Y nucleon–nucleon interaction along with th...
Article
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The reaction cross sections for neutron-rich nuclei with 7 <= Z <= 18 on a (28)Si target at intermediate energies (30-65A MeV) are calculated and are compared with the corresponding recently reported new measurements. A finite-range Glauber model along with a Coulomb modification is used. The required nucleon density distributions of the relevant p...
Article
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A comparative study of the S-matrix and the WKB methods for the calculation of the half widths of alpha decay of super heavy elements is presented. The extent of the reliability of the WKB methods is demonstrated through simple illustrative examples. Detailed calculations have been carried out using the microscopic alpha-daughter potentials generat...
Article
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Form factors for electron elastic scattering are calculated for a number of nuclei using a semi-phenomenological algebraic form for the nuclear densities. Remarkable agreement with the experiment is obtained. As a sample the results for 28Si, 90Zr, 116Sn and 208Pb are presented. This semi-phenomenological form is so designed that it incorporates co...
Article
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A comparative study of the microscopic optical potentials viz., semimicroscopic with extended Jeukenne-Lejeune-Mahaux interaction and microscopic Brueckner theory using Hamada-Johnston as well as Urbana V14 soft-core internucleon interactions, has been carried out. These microscopic optical potentials are compared with that of Dirac phenomenology (...
Article
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The calculated Q values and half widths of α-decay of superheavy elements using both the S-matrix and the WKB methods are analyzed. The calculations are carried out using the microscopically derived α-daughter potentials for the parents appearing in the α-decay chain of super heavy element (A=277,Z=112). Both the S-matrix and the WKB methods though...
Chapter
A high-sensitive fluorescence cell has been developed with an aim to perform laser spectroscopy of exotic nuclei. This fluorescence cell has been tested off-line for stable isotope 133Cs. Also, an investigation of the nuclear root mean square (r.m.s.) charge and neutron radii, and of the binding energies of the cesium long isotopic chain has been c...
Article
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The spin-orbit (SO) interaction, emerging naturally from the Relativistic Mean Field (RMF) theory is examined critically in the light of the recently measured excitation energy differences between the terminating states built on two different configurations for nuclei belonging to the lower pf shell. The calculations are carried out using the crank...
Article
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The finite range Glauber model along with the Coulomb modification is used to analyze recently measured reaction cross sections with neutron-deficient Ga, Ge, As, Se, and Br isotopes as low-energy projectiles incident on Si28 target. The required input, namely the neutron and proton density distributions of the relevant projectiles and the target,...
Article
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The essentials of the Relativistic Mean Field (RMF) theory and some of its recent applications are presented. The explicit calculations are carried out for a few selected isotopic, isotonic and isobaric chains of nuclei covering the entire periodic table. The calculated ground state properties are found to be in good agreement with the correspondin...
Article
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Systematic and consistent microscopic description of measured reaction cross sections at low projectile en-ergies is presented. Finite-range Glauber model (GM-F) along with the Coulomb modification is used. The required inputs, namely the neutron and proton density distributions of the relevant projectiles and the targets, are calculated in the rel...
Article
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The results of extensive microscopic Relativistic Mean Field (RMF) calculations for the nuclei appearing in the alpha - decay chains of recently discovered superheavy elements with Z = 109 to 118 are presented and discussed. The calculated ground state properties like total binding energies, Q values, deformations, radii and densities closely agree...
Article
We present theoretical results with experimental comparisons for the two experimentally synthesised Z=115 alpha-decay chains and predictions for a sample alpha-decay chain for Z=118. The calculations are based on the self-consistent RMF theory (NL3 parameter set) which yields the ground state properties. RMF densities and Q-values are incorporated...
Article
The results of extensive microscopic relativistic mean field (RMF) calculations for the nuclei appearing in the a-decay chains of recently discovered superheavy elements with 109 6 Z 6 118 are presented and discussed. The calculated ground-state properties like total binding energies, Q-values, deformations, radii, and densities closely agree with...
Article
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A systematic and comprehensive study of the decay half-lives of nuclei appearing in the observed α-decay chains of superheavy elements (Z=108-118) is presented. The calculation proceeds in three steps. First, the relativistic mean-field equations are solved in the axially symmetric deformed oscillator basis to obtain ground-state properties such as...
Article
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Comprehensive investigations of the observed cluster radioactivity are carried out. First, the relativistic mean field (RMF) theory is employed for the calculations of the ground-state properties of relevant nuclei. The calculations reproduce the experiment well. The calculated RMF point densities are folded with the density-dependent M3Y nucleon-n...
Article
The charge changing cross sections are investigated in the framework of the Glauber model by rearranging the transparency function. It is expressed in two parts—the projectile proton contribution (the dominating part) and the rest. The charge changing and the total neutron removal cross sections are investigated for a number of nuclei spanning diff...
Article
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The mass and the charge changing cross sections recently measured in inverse kinematics are investigated microscopically in the framework of Glauber model using the ground state point proton/neutron densities obtained in the relativistic mean field/relativistic Hartree-Bogoliubov approach. As illustrative examples, explicit results for the nuclei s...
Article
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The recent isotopic shift measurements for the chain of neon isotopes have revealed a rich structural information and very interesting anomalous behavior of the charge radii with neutron number. Here we study the systematics of the charge radii of neon isotopes within the relativistic mean field (RMF) framework. The pairing correlations are incorpo...
Article
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Calculations based on the relativistic mean field framework have been carried out for the ground state properties of the relevant nuclei appearing in the alpha -emission chain of superheavy element Z=112 . The calculations compare well with the experiment. The calculated densities along with the energy and the density dependent M3Y effective nucleo...
Article
The antiproton annihilation experiments help to extract so-called peripheral factors representing the ratio of neutron to proton densities at the annihilation site that is about 2.5 fm away from the half-density radius of the nucleus. The relativistic mean field (RMF) approach is used to calculate the peripheral factors. The RMF equations (with fro...
Article
The Relativistic Mean Field (RMF) formulation is used to describe the nuclear periphery, the central theme in the study of the unstable nuclei. First, we analyze the available antiproton annihilation experimental data in terms of the extracted peripheral factors representing the ratio of neutron to proton densities at about 2.5 fm away from the hal...
Article
The experimental ratios of the neutron to the proton densities at the nuclear periphery (≃ half-density radius + 2.5 fm) determined using very low energy anti-proton annihilation studies are compared with the predictions of the semi-phenomenological model of the nucleon density distributions. The model incorporates correctly two physical requiremen...
Article
The talk presents the current status and the perspectives of the relativistic mean field (RMF) description of various nuclear properties. Some remarkable successful applications of RMF to several different class of nuclear properties are first sketched in a short list. Three selective applications of RMF to the: Loosely bound nuclei Anti-proton \((...
Article
Nucleon (both neutron and proton) density distributions of the chain of sodium isotopes are calculated using a semi-phenomenological model of nuclear density which incorporates correctly the asymptotic behaviour and the behaviour near the centre. The experimental charge root-mean-square radii and the single neutron and proton separation energies, r...
Article
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A simple analytic expression is proposed for nucleon densities which incorporates correctly two basic physical requirements: item the asymptotic behaviour (r→∞); item the behaviour near the centre (r→0). The expression provides separately the neutron and proton densities and is suitable for the description of the loosely bound systems such as the n...
Article
A simple analytic expression is proposed for nucleon densities which incorporates correctly two basic physical requ