arXiv subjects

G. Gangopadhyay

Publications and source records attributed to G. Gangopadhyay.

45 records · Page 3Linked to original sources

arXiv2008

$α$-Decay Lifetime in Superheavy Nuclei With $A>282$

Nuclei with $A>282$ have been studied in the Relativistic Mean Field approach using the force FSU Gold and a zero range pairing interaction. The Euler-Lagrange equations have been solved in the co-ordinate space. Alpha nucleus potential has been constructed with the DDM3Y1 interaction, which has an exponential density dependence, in the double folding model using the nucleon densities in the daughter nucleus and the $α$ particle. Half lives of $α$ decay have been calculated for tunneling of the $α$ particle through the potential barrier in the WKB approximation and assuming a constant preformation probability. The resulting values agree well with experimental measurements.

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arXiv2008

Cluster decay in very heavy nuclei in Relativistic Mean Field

Exotic cluster decay of very heavy nuclei has been studied in the microscopic Super-Asymmetric Fission Model. Relativistic Mean Field model with the force FSU Gold has been employed to obtain the densities of the cluster and the daughter nuclei. The microscopic nuclear interaction DDM3Y1, which has an exponential density dependence, and the Coulomb interaction have been used in the double folding model to obtain the potential between the cluster and the daughter. Half life values have been calculated in the WKB approximation and the spectroscopic factors have been extracted. The latter values are seen to have a simple dependence of the mass of the cluster as has been observed earlier. Predictions have been made for some possible decays.

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arXiv2007

Microscopic calculation of half lives of spherical proton emitters

Half life values for proton radioactivity in nuclei have been calculated in the WKB approximation. The microscopic proton-nucleus potential has been obtained by folding the densities of daughter nuclei with two microscopic NN interactions, DDM3Y and JLM. The densities have been obtained in the Relativistic Mean Field approach in the spherical approximation using the force FSU Gold. No substantial modification of results has been observed if other common forces are employed. The calculated results for the decays from the ground state or the low-lying excited states in almost all the nuclei agree well with experimental measurements. Reasons for large deviations in a few cases have been discussed. Results in $^{109}$I and $^{112,113}$Cs show that the effect of deformation is small contrary to earlier calculations. Predictions for possible proton radioactivity have been made in two nuclei, $^{93}$Ag and $^{97}$In.

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arXiv2007

Role of pairing interaction in neutron rich odd and even Zr nuclei

Neutron rich Zr nuclei with number of neutrons between $N$= 50 and 82 are investigated in the relativistic mean field approach in co-ordinate space. The resonant levels in the positive energy continuum have been explicitly included in the calculation. Odd nuclei have been treated in the blocking approximation. Our calculation indicates that the dripline for odd mass isotopes is far away from that for the even mass ones. Pairing interaction plays a significant role in stabilizing the even isotopes, thus extending the dripline for them.

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arXiv2005

Neutron Dripline in Odd and Even Mass Calcium and Nickel Nuclei

Neutron rich Ca and Ni nuclei have been studied in spherical Relativistic Mean Field formalism in co-ordinate space. A delta interaction has been has been adopted to treat the pairing correlations for the neutrons. Odd nuclei have been treated in the blocking approximation. The effect of the positive energy continuum and the role of pairing in the stability of nuclei have been investigated using the resonant-BCS (rBCS) approach. In Ca isotopes, N=50 is no longer a magic number while in Ni nuclei, a new magic number emerges at N=70. There is a remarkable difference in the relative positions of the drip lines for odd and even isotopes. In Ca isotopes, the last bound even and odd nuclei are found to be $^{72}$Ca and $^{59}$Ca, respectively. In Ni isotopes, the corresponding nuclei are $^{98}$Ni and $^{97}$Ni, respectively. The origin of this difference in relative positions of the dripline in even and odd isotopes in the two chain is traced to the difference in the single particle level structures and consequent modification in the magic numbers in the two elements. Pairing interaction is seen to play a major role. The effect of the width of the resonance states on pairing has also been investigated.

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arXiv2005

Relativistic mean field study of neutron rich even-even C and Be isotopes

Ground state properties of neutron rich even-even Be and C nuclei have been investigated using Relativistic Mean Field approach in co-ordinate space. The positions of the neutron drip line are correctly predicted for both the elements. The nucleus $^{14}$Be shows a two neutron halo but, contrary to expectation, $^{22}$C does not exhibit any halo structure. In carbon nuclei, N=16 comes out as a new magic number. The single particle level ordering observed in stable nuclei is found to be modified in neutron rich Be isotopes. Elastic partial scattering cross sections for proton scattering in inverse kinematics have been calculated using the theoretically obtained densities for some of the nuclei and compared with available experimental data. The total cross cross sections for elastic scattering have also been calculated for all the nuclei studied showing a large increase for the halo nucleus $^{14}$Be. The nuclei have also been investigated for deformation. The nuclei $^{10}$Be and $^{16,18,20}$C are observed to be deformed in their ground state.

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arXiv2004

Deformation Projected RMF Calculation for Cr and Fe nuclei in Hybrid Derivative Coupling Model

The ground state properties of even mass Cr and Fe isotopes are studied using the generalized hybrid derivative coupling model. The energy surface of each isotope is plotted as a function of the mass quadrupole moment. The neutron numbers N=20 and N=40 are seen to remain magic numbers but N= 28 and 50 are predicted to be non-magic. The neutron number N=70 turns out to be a magic number according to the present calculation. In all the isotopes studied the calculated binding energy values are less than those obtained from experiment while the deformation is in better agreement.

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arXiv2004

Many-particle many-hole states near the magic number 20: deformed and superdeformed states

Many-particle many-hole states near the magic number 20 have been investigated in the relativistic mean field formalism using the fixed configuration method. Neutron particle-hole states in neutron-rich nuclei with $N\sim 20$, {\em i.e.} $^{30,32,34}$Mg,and $^{28,30}$Ne are studied to find out the ground state configuration. The ground state of $^{32}$Ne,Mg as well as possibly $^{34}$Mg comes out actually as particle-hole states. Proton-neutron excitation across the shell gap at 20 in nuclei with $N=Z$, {\em i.e.} $^{32}$S, $^{36}$Ar, $^{40}$Ca and $^{44}$Ti is investigated as possible origins of superdeformed configuration. Observed superdeformed bands in $^{36}$Ar and $^{40}$Ca can be described as many-particle many-hole states.

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arXiv2004

Relativistic mean field study of the newly discovered $α$-decay chain of $^{287}$115

The single particle structure of the low lying levels in the nuclei belonging to the newly observed $α$-decay chain starting from $^{287}$115 has been studied. Relativistic mean field calculation with two forces NL1 and NL3 has been performed in the blocked BCS approximation. Q-values for possible decay have been calculated and compared with experiment. Lifetime estimates obtained from phenomenological relations have also been compared.

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