We investigate the magicity of the isotopes $^{52}$Ca and $^{54}$Ca, that was recently confirmed by two experimental measurements, and relate it to like--particle and neutron--proton tensor effects within a mean--field description. By analyzing Ca isotopes, we show that the like--particle tensor contribution induces shell effects that render these nuclei more magic than they would be predicted by neglecting it. In particular, such induced shell effects are stronger in the nucleus $^{52}$Ca and the single--particle gaps are increased in both isotopes due to the tensor force. By studying $N=32$ and $N=34$ isotones, neutron--proton tensor effects may be isolated and their role analyzed. It is shown that neutron--proton tensor effects lead to increasing $N=32$ and $N=34$ gaps, when going along isotonic chains, from $^{58}$Fe to $^{52}$Ca, and from $^{60}$Fe to $^{54}$Ca, respectively.
The mean--field calculations are perfomed by employing one Skyrme parameter set, that was introduced in a previous work by fitting the tensor parameters together with the spin--orbit strength. The signs and the values of the tensor strengths are thus checked within this specific application. The obtained results indicate that the employed parameter set, even if generated with a partial adjustment of the parameters of the force, leads to the correct shell behavior and provides, in particular, a description of the magicity of $^{52}$Ca and $^{54}$Ca within a pure mean--field picture with the effective two--body Skyrme interaction.
The formation of new shell gaps in intermediate mass neutron-rich nuclei is investigated within the relativistic Hartree-Fock-Bogoliubov theory, and the role of the Lorentz pseudo-vector and tensor interactions is analyzed. Based on the Foldy-Wouthuysen transformation, we discuss in detail the role played by the different terms of the Lorentz pseudo-vector and tensor interactions in the appearing of the $N=16$, 32 and 34 shell gaps. The nuclei $^{24}$O, $^{48}$Si and $^{52,54}$Ca are predicted with a large shell gap and zero ($^{24}$O, $^{52}$Ca) or almost zero ($^{48}$Si, $^{54}$Ca) pairing g…
Using inelastic $α$-scattering at extremely forward angles, including $0^\circ$, the strength distributions of the isoscalar giant monopole resonance (ISGMR) have been measured in the $^{204,206,208}$Pb isotopes in order to examine the proposed mutually enhanced magicity (MEM) effect on the nuclear incompressibility. The MEM effect had been suggested as a likely explanation of the "softness" of nuclear incompressibility observed in the ISGMR measurements in the Sn and Cd isotopes. Our experimental results rule out any manifestation of the MEM effect in nuclear incompressibility and leave the q…
A new mass formula capable of explaining the binding energies of almost all the known isotopes from Li to Bi is prescribed. In addition to identifying the new magic number at neutron number N=16 (Z=7-9), pseudo-magic numbers at N=14 (Z=7-10), Z=14 (N=13-19), and at N=6 (Z=3-8), the formula accounts for the loss of magicity for nuclei with N=8 (Z=4) and N=20 (Z=12-17). The redefinition of the neutron drip line resulting from this formula further allows us to predict the existence of 26O,31F, 32Ne, 35Na, 38Mg, 41Al as bound nuclei and 28O as unbound.
N=Z nuclei above Ni are understood to be waiting-point nuclei in the rp-process nucleosynthesis. Investigating the experimental isotope shifts in Kr isotopes near the proton drip-line, we have discovered that N=Z rp-process nuclei $^{68}$Se, $^{72}$Kr, $^{76}$Sr and $^{80}$Zr exhibit a significant shell gap both at the proton and neutron numbers in the deformed space with the consequence that pairing correlations for protons and neutrons vanish, thus lending a double-magic character to these nuclei. A significant number of nuclei in this region are also shown to exhibit neutron magicity at N =…
The extraction of the nuclear incompressibility from the isoscalar giant monopole resonance (GMR) measurements is analysed. Both pairing and mutually enhanced magicity (MEM) effects play a role in the shift of the GMR energy between the doubly closed shell $^{208}$Pb nucleus and other Pb isotopes. Pairing effects are microscopically predicted whereas the MEM effect is phenomenologically evaluated. Accurate measurements of the GMR in open-shell Pb isotopes are called for.
In rapid-proton capture (rp-process), N=Z nuclei above Ni are understood to act as waiting-point nuclei. The N=Z nuclei 68Se, 72Kr, 76Sr and 80Zr among others are known to give rise to a large-energy x-ray flux and peaks in abundances of these nuclei synthesized in the astrophysical rp-process. Investigating the experimental isotope shifts in Kr isotopes near the proton drip-line within the framework of the deformed Relativistic Hartree-Bogoliubov theory, we have discovered that N=Z rp-process nuclei 68Se, 72Kr, 76Sr and 80Zr exhibit large shell gap both at the proton and neutron numbers in th…
Recent experimental observation of magicity in $^{78}$Ni has infused the interest to examine the persistence of the magic character across the N$=$50 shell gap in extremely neutron rich exotic nucleus $^{78}$Ni in ground as well as excited states. A systematic study of Ni isotopes and N$=$50 isotones in ground state is performed within the microscopic framework of relativistic mean-field (RMF) and the triaxially deformed Nilson Strutinsky model (NSM). Ground state density distributions, charge form factors, radii, separation energies, pairing energies, single particle energies and the shell co…
Experimental energy spectrum and B(E2) values in 68Ni and 90Zr indicate a double-magic character in these neutron-rich nuclei with N or Z=40. The data nevertheless do not show any pronounced irregularity in two-nucleon separation energy. To understand the underlying physics, we carry out both shell-model and mean-field calculations. The shell-model calculation can well reproduce all the observations. It is understood from the mean-field results for 68Ni that the shell gap at N=40 disappears due to dynamical correlations of the isovector J=0 pairing interaction. In 90Zr, however, such a dynamic…
The exotic phenomenon of two-neutron halos and 2n-radioactivity are explored in the neutron-rich $^{40,42,44}$Mg by employing various variants of the relativistic mean-field approach. The extended tail of spatial density distributions including the enhanced neutron radii and skin thickness, pairing correlations, single-particle spectrum and wave functions predict $^{40,42,44}$Mg to be strong candidates for deformed neutron halos. Weakening of magicity at N$=$28 plays a significant role in the existence of a weakly bound halo in $^{40}$Mg which is currently the heaviest isotope of Mg accessible…
Various ground state properties are explored for full isotonic(isotopic) chain of neutron number N(proton number Z)$=$40 using different families of Relativistic Mean-Field theory. Several properties such as nucleon separation energies, pairing energies, deformation, radii and nucleon density distributions are evaluated and compared with the experimental data as well as those from other microscopic and macroscopic models. N$=$40 isotonic chain presents ample of support for the neutron magicity and articulates double magicity in recently discovered $^{60}$Ca and $^{68}$Ni. Our results are in cl…
A novel shape evolution in the Sn isotopes by the state-of-the-art application of the Monte Carlo Shell Model calculations is presented in a unified way for the 100-138Sn isotopes. A large model space consisting of eight single-particle orbits for protons and neutrons is taken with the fixed Hamiltonian and effective charges, where protons in the 1g9/2 orbital are fully activated. While the significant increase of the B(E2; 0+1 -> 2+1) value, seen around 110Sn as a function of neutron number (N), has remained a major puzzle over decades, it is explained as a consequence of the shape evolution …
The shapes of neutron-rich exotic Ni isotopes are studied. Large-scale shell model calculations are performed by advanced Monte Carlo Shell Model (MCSM) for the $pf$-$g_{9/2}$-$d_{5/2}$ model space. Experimental energy levels are reproduced well by a single fixed Hamiltonian. Intrinsic shapes are analyzed for MCSM eigenstates. Intriguing interplays among spherical, oblate, prolate and gamma-unstable shapes are seen including shape fluctuations, $E$(5)-like situation, the magicity of doubly-magic $^{56,68,78}$Ni, and the coexistence of spherical and strongly deformed shapes. Regarding the last …
New data on proton and neutron single-particle energies $E_{nlj}$ of Si isotopes with neutron number $N$ from 12 to 28 as well as occupation probabilities $N_{nlj}$ of single particle states of stable isotopes $^{28,30}$Si near the Fermi energy were obtained by the joint evaluation of the stripping and pick-up reaction data and excited state decay schemes of neighboring nuclei. The evaluated data indicate following features of single-particle structure evolution: persistence of $Z = 14$ subshell closure with $N$ increase, the new magicity of the number $N = 16$, and the conservation of the mag…
We probe the $N=82$ nuclear shell closure by mass measurements of neutron-rich cadmium isotopes with the ISOLTRAP spectrometer at ISOLDE-CERN. The new mass of $^{132}$Cd offers the first value of the $N=82$, two-neutron shell gap below $Z=50$ and confirms the phenomenon of mutually enhanced magicity at $^{132}$Sn. Using the recently implemented phase-imaging ion-cyclotron-resonance method, the ordering of the low-lying isomers in $^{129}$Cd and their energies are determined. The new experimental findings are used to test large-scale shell-model, mean-field and beyond-mean-field calculations, a…
We studied the role of the tensor interaction in He isotopes systematically on the basis of the tensor-optimized shell model (TOSM). We use a bare nucleon-nucleon interaction AV8 obtained from nucleon-nucleon scattering data. The short-range correlation is treated in the unitary correlation operator method (UCOM). Using the TOSM+UCOM approach, we investigate the role of tensor interaction on each spectrum in He isotopes. It is found that the tensor interaction enhances the LS splitting energy observed in 5He, in which the p1/2 and p3/2 orbits play different roles on the tensor correlation. In …
In our recent paper [Phys. Lett. B 753, (2016) 122], we have shown that both the odd and even tensor electric transition probabilities exhibit similar behavior within the generalized seniority scheme in a multi-j environment. This microscopic approach was used to show for the first time the occurrence of seniority isomers in the $ {13}^-$ isomers of Sn-isotopes, which decay by odd tensor $E1$ transition to the same seniority ($Δv = 0$) state. In this letter, we extend our studies to odd tensor $E3$ transitions connecting different seniority states ($Δv = 2$), and show for the first time that t…
The inversion of 3/2$^{-}$ and 5/2$^{-}$ levels in heavier Cu isotopes is one of the most visible example of shell-evolution, caused by the strong monopole attraction between the nucleons occupying the orbitals $π0f_{5/2}$ and $ν0g_{9/2}$. The tensor part of the nucleon-nucleon interaction is expected to be the driving force behind this monopole migration. In shell model framework, usually spin-tensor decomposition is used to get the information of individual force components to the shell evolution, however, in the present scenario, this method can not apply on \textit{pfg} model space due to …
We show how the shape evolution of the neutron-rich exotic Si and S isotopes can be understood as a Jahn-Teller effect that comes in part from the tensor-driven evolution of single-particle energies. The detailed calculations we present are in excellent agreement with known experimental data, and we point out of new features that should be explored in new experiments. Potential energy surfaces are used to understand the shape evolutions. The sub-shell closed nucleus, $^{42}$Si, is shown to be a perfect example of a strongly oblate shape instead of a sphere through a robust Jahn-Teller mechanis…
We calculate the single particle spectrum of the double magic nucleus $^{78}$Ni in a Hartree-Fock approach using the Skyrme density-dependent effective interaction containing central, spin-orbit and tensor parts. We show that the tensor part has an important effect on the spin-orbit splitting of the proton $1f$ orbit which may explain the survival of magicity so far from the stability valley. We confirm the inversion of the $1f5/2$ and $2p3/2$ levels at the neutron number 48 in the Ni isotopic chain expected from previous Monte Carlo shell model calculations and supported by experimental obser…
Recently, we developed a mean-field-type framework which treats the correlation induced by the tensor force. To exploit the tensor correlation we introduce single-particle states with the parity and charge mixing. To make a total wave function have a definite charge number and a good parity, the charge number and parity projections are performed. Taking a variation of the projected wave function with respect to single-particle states a Hartree-Fock-like equation, the charge- and parity-projected Hartree-Fock equation, is obtained. In the charge- and parity-projected Hartree-Fock method, we sol…
The evolution of the energy difference between the neutron states $1i_{13/2}$ and $1h_{9/2}$ in the $N=82$ isotones and that between the proton states $1h_{11/2}$ and $1g_{7/2}$ in the $Z = 50$ isotopes are investigated within the framework of the relativistic Hartree-Fock theory, using the density-dependent effective interactions PKA1 and PKO$i$ ($i = 1 $, $ 2 $, $ 3 $). By identifying the contributions of the tensor force, which is naturally induced via the Fock terms, we find that the tensor force plays crucial roles in the evolution of the shell structure. The strength of the tensor force …
We have employed RMF+BCS (relativistic mean-field plus BCS) ap- proach to study behaviour of N = 16 shell closure with the help of ground state properties of even-even nuclei. Our present investigations include sin- gle particle energies, deformations, separation energies as well as pairing energies etc. As per recent experiments showing neutron magicity at N = 16 for O isotopes, our results indicate a strong shell closure at N = 16 in 22C and 24O. A large gap is found in between neutron 2s1/2 and 1d3/2 states for 22C and 24O. These results are also supported by a sharp increase in two neutron…
Shape evolution of Zr nuclei are investigated by the axial Hartree-Fock (HF) calculations using the semi-realistic interaction M3Y-P6, with focusing on roles of the tensor force. Deformation at $N\approx 40$ is reproduced, which has not been easy to describe within the self-consistent mean-field calculations. The spherical shape is obtained in $46\leq N\leq 56$, and the prolate deformation is predicted in $58\leq N\leq 72$, while the shape switches to oblate at $N=74$. The sphericity returns at $N=80$ and $82$. The deformation in $60\lesssim N\lesssim 70$ resolves the discrepancy in the previo…
Approximations made to estimate two-nucleon transfer probabilities in ground-state to ground-state transitions and physical interpretation of these probabilities are discussed. Probabilities are often calculated by approximating both ground states, of the initial nucleus A and of the final nucleus A\pm 2 by the same quasiparticle vacuum. We analyze two improvements of this approach. First, the effect of using two different ground states with average numbers of particles A and A\pm2 is quantified. Second, by using projection techniques, the role of particle number restoration is analyzed. Our a…
In this paper we study the issue of the puzzle of the radii of calcium isotopes. Despite an excess of eight neutrons, strangely $^{48}{\rm Ca}$ exhibits essentially the same charge radius as $^{40}{\rm Ca}$ does. A fundamental microscopic description of this is still lacking. Also strange is a peak in charge radius of calcium at N = 24. The $^{52}{\rm Ca}$ (N = 32) nucleus, well known to be doubly magical, amazingly has recently been found to have a very large charge radius. Also amazing is the property of $^{42}_{14}{\rm Si}_{28}$ which simultaneously appears to be both magical/spherical and …
The doubly odd Ta isotopes are studied within the framework of the particle-rotor model. The main aim of this study is to obtain information on the neutron-proton interaction in deformed nuclei, with particular attention focused on the role of the tensor force. To this end, both zero-range abd finite-range phenomenological interactions are considered. Comparison of the calculated results with experimental data provides evidence of the importance of the tensor-force effects. We have also performed calculations using a realistic two-body G matrix for the neutron proton interaction. Some prelimin…
We study the effects of the tensor term of the effective nucleon-nucleon interaction on nuclear excited states. Our investigation has been conducted by using a self-consistent Random Phase Approximation approach. We investigate various nuclei in different regions of the isotopes chart. Results for a set of calcium isotopes are shown.
The similar behavior of the B(E1) values of the recently observed 13- odd tensor E1 isomers and the B(E2) values of the 10+ and 15- even tensor E2 isomers in the Sn-isotopes has been understood in terms of the generalized seniority for multi-j orbits by using the quasi-spin scheme. This simple approach proves to be quite successful in explaining the measured transition probabilities and the corresponding half-lives in the high-spin isomers of the semi-magic Sn-isotopes. Hence, we show for the first time the occurrence of seniority isomers in the 13- Sn-isomers, which decay by odd-tensor E1 tra…
The shell corrections and shell gaps in nuclei are systematically studied with the latest Weizsäcker-Skyrme (WS4) mass model. We find that most of asymmetric nuclei with (sub)-shell closures locate along the shell stability line (SSL), $N=1.37Z+13.5$, which might be due to a strong correlation between neutrons and protons near Fermi surface. The double magicity of nuclei $^{46}$Si and $^{78}$Ni is predicted according to the corresponding shell gaps, shell corrections and nuclear deformations. The unmeasured super-heavy nuclei $^{296}$118 and $^{298}$120, with relatively large shell gaps and sh…
Much interest has been devoted to the shape evolution of neutron-rich Si isotopes recently both experimentally and theoretically. We provide our study of $^{28-42}$Si by Skyrme-Hartree-Fock model with BCS approximation for the pairing channel. We use an empirical pairing parameter deduced from the experimental binding energy data for each nuclei and each Skyrme parametrization. The recent highlight of the deformation change from a prolate shape of $^{38}$Si to an oblate shape of $^{42}$Si is confirmed in the present model. We also emphasize the role of tensor force on deformations of neutron-r…
We study the Li isotopes systematically in terms of the tensor-optimized shell model (TOSM) by using a bare nucleon-nucleon interaction as the AV8' interaction. The short-range correlation is treated in the unitary correlation operator method (UCOM). Using the TOSM+UCOM approach, we investigate the role of the tensor force on each spectrum of the Li isotopes. It is found that the tensor force produces quite a characteristic effect on various states in each spectrum and those spectra are affected considerably by the tensor force. The energy difference between the spin-orbit partner, the p1/2 an…
We study tensor and pairing effects on the quadruple deformation of neon isotopes based on a deformed Skyrme-Hartree-Fock model with BCS approximation for the pairing channel. We extend the Skyrme-Hartree-Fock formalism for the description of single- and double-lambda hypernuclei adopting two different hyperon-nucleon interactions. It is found that the interplay of pairing and tensor interactions is crucial to derive the deformations in several neon isotopes. Especially, the shapes of $^{26,30}$Ne are studied in details in comparisons with experimentally observed shapes. Furthermore the deform…
We show how shape transitions in the neutron-rich exotic Si and S isotopes occur in terms of shell-model calculations with a newly constructed Hamiltonian based on V_MU interaction. We first compare the calculated spectroscopic-strength distributions for the proton 0d_5/2,3/2 and 1s_1/2 orbitals with results extracted from a 48Ca(e,e'p) experiment to show the importance of the tensor-force component of the Hamiltonian. Detailed calculations for the excitation energies, B(E2) and two-neutron separation energies for the Si and S isotopes show excellent agreement with experimental data. The poten…
Shell structure in the neutron-rich Ca and Ni nuclei is investigated by the spherical Hartree-Fock calculations with the semi-realistic $NN$ interactions. Specific ingredients of the effective interaction, particularly the tensor force, often play a key role in the $Z$ dependence of the neutron shell structure. Such examples are found in N=32 and N=40; N=32 becomes magic or submagic in $^{52}$Ca while its magicity is broken in $^{60}$Ni, and N=40 is submagic (though not magic) in $^{68}$Ni but not in $^{60}$Ca. Comments are given on the doubly magic nature of $^{78}$Ni. We point out that the l…
An influence of the phonon-phonon coupling (PPC) on the $β$-decay half-lives and multi-neutron emission probabilities is analysed within the microscopic model based on the Skyrme interaction with tensor components included. The finite-rank separable approximation is used in order to handle large two-quasiparticle spaces. The even-even nuclei near the r-process pathes at $N=82$ are studied. The characteristics of ground states, $2^+$ excitations and $β$-decay strength of the neutron-rich Cd isotopes are treated in detail. It is shown that a strong redistribution of the Gamow-Teller strength due…
We investigate the nature and impact of shell effects on nuclear level density (NLD) and particle emission probability as a function of temperature in a microscopic theoretical framework of Statistical Model for nuclei ranging from neutron deficient to neutron rich isotopes of Z$=$ 27$-$35. Critical temperatures are traced for neighbouring even, odd, closed shell and mid$-$shell nuclei which respond to excitations differently due to their varying stability and structural effects. Importance of the shell effects and shell correction energy is reflected significantly in NLD variation which slowl…
Beyond mean-field methods based on restoration of symmetries and configuration mixing by the generator coordinate method (GCM) enable to calculate on the same footing correlations in the ground state and the properties of excited states. Excitation energies are often largely overestimated, especially in nuclei close to magicity, even when transition probabilities are well-described. We analyse here the origin of this failure. The first part of the paper compares realistic projected GCM and QRPA calculations for selected Sn isotopes performed with the same effective Skyrme interaction. Although…
We discuss the need of including tensor terms in the effective Gogny interaction used in mean-field calculations. We show in one illustrative case that, with the usual tensor term that is employed in the Skyrme interaction (and that allows us to separate the like-nucleon and the neutron-proton tensor contributions), we can describe the evolution of the N=28 neutron gap in calcium isotopes. We propose to include a tensor and a tensor-isospin term in finite-range interactions of Gogny type. The parameters of the two tensor terms allow us to treat separately the like-nucleon and the neutron-proto…
We computed ground-state energies of calcium isotopes from 42Ca to 48Ca by means of the Auxiliary Field Diffusion Monte Carlo (AFDMC) method. Calculations were performed by replacing the 40Ca core with a mean-field self consistent potential computed using Skyrme interaction. The energy of the external neutrons is calculated by projecting the ground-state from a wave function built with the single particle orbitals computed in the self consistent external potential. The shells considered were the 1F_7/2 and the 1F_5/2. The Hamiltonian employed is semi-realistic and includes tensor, spin--orbit …
The role of the tensor part of the nuclear interaction is actively investigated in recent years due to experimental advancement yielding new data in nuclei far from the $β$-stability line. In this article we study the effect of this part of the nuclear interaction on deformed neutron magic numbers in the rare-earth region within the Skyrme energy-density functional for various TIJ \cite{lesinski:2007} parametrizations. Two quantities signaling magic numbers are considered: two-neutron separation energies and single-particle energies. They are calculated in isotopic series involving well-deform…
In this work we study the effect of the nuclear tensor force on properties related with deformation. We focus on isotopes in the Mg, Si, S, Ar, Sr and Zr chains within the Hartree-Fock-Bogoliubov theory using the D1ST2a Gogny interaction. Contributions to the tensor energy in terms of saturated and unsaturated subshells are analyzed. Like-particle and proton-neutron parts of the tensor term are independently examinated. We found that the tensor term may considerably modify the potential energy landscapes and change the ground state shape. We analyze too how the pairing characteristics of the g…
We analyze the evolution with increasing isospin asymmetry of the proton single-particle states 2s1/2 and 1d3/2 in Ca isotopes, using non-relativistic and relativistic mean field approaches. Both models give similar trends and it is shown that this evolution is sensitive to the neutron shell structure, the two states becoming more or less close depending on the neutron orbitals which are filled. In the regions where the states get closer some parametrizations predict an inversion between them. This inversion occurs near $^{48}$Ca as well as very far from stability where the two states systemat…
We systematically study the effect of the J^2 tensor terms in the Skyrme energy functional on properties of spherical nuclei. We build a set of 36 parameterizations covering a wide range of the corresponding parameter space. We analyze the impact of the tensor terms on the evolution of single-particle-level splittings along chains of semi-magic nuclei in spherical calculations. We find that positive values of the coupling constants of proton-neutron and like-particle tensor terms allow for a qualitative description of the evolution of neutron and proton single-particle level splittings in chai…
In the framework of a Skyrme-Hartree-Fock approach combined with BCS method, the role of the tensor force on the pseudospin energy splitting for tin isotope chain is investigated. The tensor force turns out to obviously affect the pseudospin energy splitting of the spin-unsaturated nuclei. Since the tensor force shifts the single-particle levels, it modifies the single-particle level density and the shell correction energy thereof. The influence of the tensor interaction on shell correction energy is considerable according to our analysis taking a magic nucleus $^{132}$Sn as well as a superhea…
We make a systematic study of Li isotopes (A=9,10,11) in the tensor optimized shell model for 9Li and treat the additional valence neutrons in the cluster model approach by taking into account the Pauli-blocking effect caused by the tensor and pairing correlations. We describe the tensor correlations in 9Li fully in the tensor-optimized shell model, where the variation of the size parameters of the single particle orbits is essential for getting strong tensor correlations. We have shown in our previous study that in $^{10,11}$Li the tensor and pairing correlations in 9Li are Pauli-blocked by a…
Melting of N=20 shell and development of N = 16 and N = 34 shells for neutron-rich nuclei have been studied extensively through inclusion of tensor interaction in Skyrme Hartree Fock theory optimized to reproduce the splitting neutron 1f states of 40, 48Ca and 56Ni nuclei. Evolution of gap generated by the energy difference of single particle levels neutron 2s1/2 and neutron 1d3/2 state has been found to be responsible for the development of a shell closure at N = 16. The splitting pattern of spin-orbit partners 2p shell model state in Ca, Ti, Cr, Fe and Ni isotopes indicates formation of a ne…
We use a relativistic mean field model to study the charge density distributions of exotic oxygen isotopes. Nonlinear isoscalar-isovector terms which are not constrained by the present data are considered and the $ρNN$ tensor coupling that does not affect the symmetry energy in the mean field model is included. Strong correlations between the neutron radius of $^{208}$Pb and the charge radius of $^{12,13,23,24}$O are found. The $ρNN$ tensor coupling explicitly enhances the radius correlations between $^{23,24}$O and $^{208}$Pb. This enhancement is due to the neutron occupation of the orbital $…
We present a study of the effects of the tensor-isospin term of the effective interaction in Hartree-Fock and Random Phase Approximation calculations. We used finite-range forces of Gogny type, and we added to them a tensor-isospin term which behaves, at large internucleonic distances, as the analogous term of the microscopic interactions. The strength of this tensor force has been chosen to reproduce the experimental energy of the lowest 0$^-$ excited state in $^{16}$O, which shows large sensitivity to this term of the interaction. With these finite-range interactions, we have studied the eff…
Semi-realistic nucleon-nucleon interactions applicable to the self-consistent mean-field (both Hartree-Fock and Hartree-Fock-Bogolyubov) calculations are developed, by modifying the M3Y interaction. The modification is made so as to reproduce binding energies and rms matter radii of doubly magic nuclei, single-particle levels in $^{208}$Pb, and even-odd mass differences of the Sn isotopes. We find parameter-sets with and without the tensor force. The new interactions are further checked by the saturation properties of the uniform nuclear matter including the Landau-Migdal parameters. By the me…
In the present study, we have investigated the impact of the tensor force on fission paths, in particular the symmetric and asymmetric barriers in 230 Th, 226 Th, 222 Th and 216 Th isotopes which display an asymmetric to symmetric fission transition. This analysis has been performed within the HFB approach with (Q 20 ,Q 30 ,Q 40 ) as collective variable constraints, using the D1ST2a Gogny+tensor term interaction and comparing to the standard D1S Gogny interaction results. The effects from the tensor term on the potential energy surface landscape, and especially on barrier heights and its topol…
The tensor force, as an important component of strong nuclear force, generates a variety of intriguing effects ranging from few-body systems to neutron stars. It is responsible for the nucleon-nucleon correlation beyond mean-field approximation, and is accordingly proved to play no role in the standard Skyrme energy density functionals in the present work. Therefore, the Skyrme's original tensor interaction that is extensively-employed presently is invalid. As an alternative strategy, we introduced a central interaction, i.e., the $\bm{σ}_{1}\cdot \bm{σ}_{2}$ term, to improve the description o…
