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M. Ikram

Publications and source records attributed to M. Ikram.

11 recordsLinked to original sources
arXiv2026

Non-Hermitian curved space via inverted wave equation

Directly solving graded materials from amplitude and phase was a method developed following transformation optics (TO), which provided reflectionless media for an incidence wave. However, this inverting method gives Hermitian media thus not applicable to non-Hermitian (NH) photonics. In this Letter we then design NH media offering more freedom to manipulate waves of no reflection. Our picture of curved-space powered with gain and loss, is exemplified by three types: amplitude controlling, phase conversion, and direction shunting. These examples showcase precise wave manipulation in a surprisingly simple manner, which is implementable in photonic platform similar to TO.

physics.optics↗
arXiv2024

Microscopic Investigation of Ground State Properties and Shape Evolution in Osmium Isotopes

The present study focuses on investigating the shape evolution of neutron-rich even-even Osmium (Os) transitional nuclei within the range of neutron number N = 82 to N = 190. The investigation is conducted using density-dependent meson-nucleon and point-coupling models within the framework of the covariant density functional theory (CDFT). Additionally, the results obtained from the CDFT calculations are compared with those obtained using the relativistic mean-field model with a non-linear meson-nucleon interaction. The potential energy curve for Os isotopes (ranging from $^{158}$Os to $^{260}$Os) is analyzed in order to identify phase shape transitions, such as oblate-spherical-prolate. Furthermore, ground state bulk properties are calculated to gain insights into the structure of Os isotopes. The self-consistent calculations reveal a clear shape transition in the even-even Os isotopes, and overall, good agreement is observed among the different models employed as well as with the available experimental data.

nucl-th↗
arXiv2020

A study of nuclear radii and neutron skin thickness of neutron-rich nuclei near the neutron drip line

We studied the charge radius ($r_{c}$), neutron radius ($r_n$), and neutron skin-thickness ($Δr=r_n-r_p$) over a chain of isotopes from C to Zr with the stable region to the neutron drip line. Theoretical calculations are done with axially deformed self-consistent relativistic mean-field theory (RMF) with effective nonlinear NL3 and NL3* interactions. The theoretically estimated values are compared with available experimental data and a reasonable agreement are noted. We additionally assessed the two-neutron separation energy ($S_{2n}$) to mark the drip line nuclei of the considered isotopic series. In the reference of $S_{2n}$, neutron magicity is also discussed. The calculated neutron radii are compared with empirical estimation made by $r=r_0N^{1/3}$ to examine the abnormal trend of the radius for neutron drip line nuclei. In view to guide the long tails, the density distribution for some skin candidates is analyzed. Finally, neutron skin thickness is observed for the whole considered isotopic series.

nucl-th↗
arXiv2017

Theoretical studies on structural properties and decay modes of $^{284-375}$119 isotopes

In this manuscript, we analyze the structural properties of $Z=119$ superheavy nuclei in the mass range of 284 $\le$ A $\le$ 375 within the framework of axially deformed relativistic mean field theory (RMF) and calculate the binding energy, radii, quadrupole deformation parameter, separation energies and density profile. To investigate the phenomenon of shape coexistence the RMF calculations are performed within three possible solutions i.e. prolate, oblate and spherical configurations. To get a better visualization of nucleon and total matter distribution, two-dimensional contour representation of density distribution for $^{291}$119 and $^{303}$119 has been made. Further, a competition between possible decay modes such as $\alpha-$decay, $\beta-$decay and spontaneous fission (SF) of the isotopic chain of $Z=119$ superheavy nuclei under study is systematically analyzed within self-consistent relativistic mean field model. Our analysis confirmed that $\alpha-$decay is restricted within the mass range 284 $\leq$ A $\leq$ 296 and thus being the dominant decay channel in this mass range. There is no possibility of $\beta-$decay for the considered isotopic chain. In addition, we forecasted the $\alpha-$decay chain of fission survival nuclides i.e. $^{284-296}$119 and found as one $\alpha$ chain from $^{284}$119 and $^{296}$119, two consistent $\alpha$ chains from $^{285}$119 and $^{295}$119, three consistent $\alpha$ chains from $^{286}$119 and $^{294}$119, four consistent alpha chains from $^{287}$119, six consistent alpha chains from $^{288-293}$119. Thus, such studies can be of great significance to the experimentalists in very near future for synthesizing $Z=119$ superheavy nuclei.

nucl-th↗
arXiv2017

A Study of Multi$Λ$ hypernuclei within Spherical Relativistic Mean-field Approach

This research article is a follow up of earlier work by M. Ikram et al., reported in International Journal of Modern Physics E {\bf{25}}, 1650103 (2016) wherein we searched for $Λ$ magic numbers in experimentally confirmed doubly magic nucleonic cores in light to heavy mass region (ie.$^{16}O - ^{208}Pb$) by injecting $Λ$'s into them. In present manuscript, working within the state-of-art relativistic mean field theory with inclusion of $ΛN$ and $ΛΛ$ interaction in hypernuclei using the predicted doubly magic nucleonic cores ie. $^{292}$120, $^{304}$120, $^{360}$132, $^{370}$132, $^{336}$138, $^{396}$138 of elusive superheavy mass regime. In analogy to well established signatures of magicity in conventional nuclear theory, the prediction of hypernuclear magicity are made on the basis of one-, two-$Λ$ separation energy ($S_Λ, S_{2Λ}$) and two lambda shell gaps ($δ_{2Λ}$) in multi-$Λ$ hypernuclei. The calculations suggest that the $Λ$ numbers 92, 106, 126, 138, 184, 198, 240, and 258 might be the $Λ$ shell closures after introducing the $Λ$'s in elusive superheavy nucleonic cores. Moreover, in support of $Λ$ shell closure the investigation of $Λ$ pairing energy and effective $Λ$ pairing gap has also been made. The appearance of new lambda shell closures other than the nucleonic ones predicted by various relativistic and non-relativistic theoretical investigations can be attributed to the relatively weak strength of spin-orbit coupling in hypernuclei compared to normal nuclei.

nucl-th↗
arXiv2016

Structural and decay properties of $Z=132,138$ superheavy nuclei

In this paper, we analyze the structural properties of $Z=132$ and $Z=138$ superheavy nuclei within the ambit of axially deformed relativistic mean-field framework with NL$3^{*}$ parametrization and calculate the total binding energies, radii, quadrupole deformation parameter, separation energies, density distributions. We also investigate the phenomenon of shape coexistence by performing the calculations for prolate, oblate and spherical configurations. For clear presentation of nucleon distributions, the two-dimensional contour representation of individual nucleon density and total matter density has been made. Further, a competition between possible decay modes such as $α$-decay, $β$-decay and spontaneous fission of the isotopic chain of superheavy nuclei with $Z=132$ within the range 312 $\le$ A $\le$ 392 and 318 $\le$ A $\le$ 398 for $Z=138$ is systematically analyzed within self-consistent relativistic mean field model. From our analysis, we inferred that the $α$-decay and spontaneous fission are the principal modes of decay in majority of the isotopes of superheavy nuclei under investigation apart from $β$ decay as dominant mode of decay in $^{318-322}138$ isotopes.

nucl-th↗
arXiv2016

Quest for magicity in hypernuclei

In present study, we search the lambda magic number in hypernuclei within the framework of relativistic mean field theory (RMF) with inclusion of hyperon-nucleon and hyperon-hyperon potentials. Based on one- and two-lambda separation energy and two-lambda shell gap, 2, 8, 14, 18, 20, 28, 34, 40, 50, 58, 68, 70 and 82 are suggested to be the $Λ$ magic number within the present approach. The weakening strength of $Λ$ spin-orbit interaction is responsible for emerging the new lambda shell closure other than the model scheme. The predicted $Λ$ magic numbers are in remarkable agreement with earlier predictions and hypernuclear magicity quite resembles with nuclear magicity. %Our results also support the nuclear magicity, Our results are supported by nuclear magicity, where neutron number N = 34 is experimentally observed as a magic which is one of the $Λ$ closed shell in our predictions. In addition, the stability of hypernuclei is also examined by calculating the binding energy per particle, where Ni hypernucleus is found to be most tightly bound triply magic system in considered hypernuclei. Nucleon and lambda density distributions are observed and it is found that introduced $Λ$'s have significant impact on total density and reduces the central depression of the core nucleus. Nucleon and lambda mean field potentials and spin-orbit interaction potentials are also observed for predicted triply magic hypernuclei and the addition of $Λ$'s affect the both the potentials to a large extent. The single-particle energy levels are also analyzed to explain the shell gaps for triply magic multi-$Λ$ hypernuclei.

nucl-th↗
arXiv2014

A relativistic mean field study of multi-strange system

We study the binding energies, radii, single-particle energies, spin-orbit potential and density profile for multi-strange hypernuclei in the range of light mass to superheavy region within the relativistic mean field (RMF) theory. The stability of multi-strange hypernuclei as a function of introduced hyperons ($Λ$ and $Σ$) is investigated. The neutron, lambda and sigma mean potentials are presented for light to superheavy hypernuclei. The inclusion of hyperons affects the nucleon, lambda and sigma spin-orbit potentials significantly. The bubble structure of nuclei and corresponding hypernuclei is studied. The nucleon and lambda halo structure are also investigated. A large class of bound multi-strange systems formed from the combination of nucleons and hyperons (n, p, $Λ$, $Σ^+$ and n, p, $Λ$, $Σ^-$) is suggested in the region of superheavy hypernuclei which might be stable against the strong decay. These multi-strange systems might be produced in heavy-ion reactions.

nucl-th↗
arXiv2014

$Λ-$hyperon interaction with nucleons

We study the interaction of $Λ-$hyperon with proton and neutron inside a nucleus within the framework of relativistic mean field formalism. The single particle energy levels for some of the specific proton and neutron orbits are analyzed with the addition of $Λ-$successively. We found that the interaction of $Λ$ with neutron is more stronger than proton.

nucl-th↗
arXiv2014

Effects of isovector scalar $δ$-meson on hypernuclei

We analyze the effects of $δ-$ meson on hypernuclei within the frame-work of relativistic mean field theory. The $δ-$ meson is included into the Lagrangian for hypernuclei. The extra nucleon-meson coupling ($g_δ$) affects the every piece of physical observables, like binding energy, radii and single particle energy of hypernuclei. The lambda mean field potential is investigated which is consistent with other predictions. Flipping of single particle energy levels are observed with the strength of $g_δ$ in the considered hypernuclei as well as normal nuclei. The spin-orbit potentials are observed for considered hypernuclei and the effect of $g_δ$ on spin-orbit potentials is also analyzed. The calculated single-$Λ$ binding energies ($B_Λ$) are quite agreeable with the experimental data.

nucl-th↗