24Mg Nuclei Research Articles

Re-analysis of the Gamow-Teller distributions for [formula omitted] nuclei, 24Mg, 28Si, and 32S

The Gamow-Teller (GT) strength distributions of sd-shell N=Z nuclei (24Mg, 28Si, and 32S) are investigated within the framework of proton–neutron quasi-particle random phase approximation (pn-QRPA) using a deformed basis. The nuclear properties of these special nuclei were investigated by the Relativistic Mean Field (RMF) model. The RMF framework with density-dependent interactions (DD-PC1 and DD-ME2) was employed to compute ground-state deformation parameters (β2) using potential energy curves. The β2 values computed from the RMF and the finite range droplet model (FRDM) were employed as a free parameter in the pn-QRPA calculation to investigate the resulting GT strength distributions. The present model-based analyses compare well with the observed data.

Analysis of elastic scattering of 6,7Li and 20Ne from 24Mg nucleus using microscopic potentials

The experimentally available angular distributions (ADs) for [Formula: see text]Li and [Formula: see text]Ne ions elastically scattered from a [Formula: see text]Mg target are reanalyzed using various nuclear potentials based on phenomenological as well as microscopic approaches. The considered data are [Formula: see text] ADs at [Formula: see text], 88 and 240[Formula: see text]MeV; [Formula: see text] ADs at [Formula: see text], 34 and 88[Formula: see text]MeV; and [Formula: see text] ADs at [Formula: see text], 60, 80, 90 and 100[Formula: see text]MeV. Special emphasis is given on the ([Formula: see text]) and ([Formula: see text]) cluster structures of the 6Li and 7Li weakly bound projectiles, which appear at relatively low energies of [Formula: see text] and 2.468[Formula: see text]MeV, respectively. Furthermore, the [Formula: see text]Ne stable nucleus is a candidate to reveal the [Formula: see text]O cluster structure at an energy of 4.73[Formula: see text]MeV. These systems are analyzed within the framework of the cluster folding model by taking into consideration the aforementioned cluster nature of the 6Li, 7Li and [Formula: see text]Ne projectiles. The adopted approaches fairly reproduced the experimental ADs.

CALCULATION OF THE INELASTIC LONGITUDINAL ELECTRON SCATTERING OF 20Ne AND 24Mg NUCLEI

The inelastic longitudinal electron scattering form factors F(q)'s, an expression for the transition charge density are studied where the deformation in nuclear collective modes is taken into consideration besides the shell model transition density. The core polarization transition density is evaluated by adopting the shape of Tassie model together with form of the ground state two-body charge density distributions which included the effect of short range correlation(SRC). It is noticed that the core polarization effects which represent the collective modes are essential in obtaining a good agreement between the calculated inelastic longitudinal F(q)'s and those of experimental data for 20Ne and 24Mg nuclei.

Study Magnetic Electron Scattering Form Factor of Magnesium 24Mg

The magnetic form factors (ML) of inelastic electron scattering of magnesium nuclei 24Mg were studied computationally using Oxbash code. The energy levels of this nucleus were calculated through the shell model and using the model space (ZBM, PSD,SPSDPF and SD). For SD used two novel USD-type Hamiltonians, USDC and USDI, as well as modifications to these interactions, USDCm and USDIm. All the calculated values that were studied were compared with the available practical data, and it was also based on the data of the NNDC website. This study showed agreement between the calculated results and the experimental data after changing the values of g-factors where they were (𝑔𝑙 𝑝= 1.060 and 𝑔𝑙 𝑛= -0.060).

Direct 16O-cluster knockout from 24Mg[formula omitted

The O(g.s.)16+8Be(g.s.) structure of the ground state of 24Mg nucleus has been probed experimentally using direct knockout reaction Mg24(O16,216O)8Be in the quasi free scattering kinematics domain. The direct 16O-cluster knockout finite range prediction indicates a fair amount of O(g.s.)16+8Be(g.s.) component in the Mg(g.s.)24.

Large Scale Shell Model Calculations of the Negative-Parity States Structure in 24Mg Nucleus

The negative-parity states of 24Mg nucleus are investigated within the shell model. We are based on the calculations of energy levels, total squared form factors, and transition probability using the p-sd-pf (PSDPF) Hamiltonian in a large model space (0 + 1) hW. The comparison between the experimental and theoretical states showed a good agreement within a truncated model space. The PSDPF-based calculations successfully reproduced the data on the total squared form factors and transition probabilities of the negative-parity states in 24Mg nucleus. These quantities depend on the one-body density matrix elements that are obtained from the PSDPF Hamiltonian. The wave functions of radial one-particle matrix elements calculated with the harmonic-oscillator potential are suitable to predict experimental data by changing the center-of-mass corrections.

Nuclear incompressibility from spherical and deformed nuclei

We present an analysis based on the deformed Quasi Particle Random Phase Approximation, on top of a deformed Hartree-Fock-Bogoliubov description of the ground state, aimed at studying the isoscalar monopole and quadrupole response in a deformed nucleus. This analysis is motivated by the need of understanding the coupling between the two modes and how it might affect the extraction of the nuclear incompressibility from the monopole distribution. After discussing this motivation, we present the main ingredients of our theoretical framework, and we show some results obtained with the SLy4 and SkM* interactions for the nucleus 24Mg.

Coulomb form factors of 25Mg nuclei using Bohr–Mottelson collective model with Skyrme interaction potential

Coulomb [Formula: see text] and C4 form factors to the 5/2[Formula: see text], 7/2[Formula: see text], 9/2[Formula: see text], 9/2[Formula: see text] and 11/2[Formula: see text] states in [Formula: see text]Mg nuclei have been studied using shell model calculations. The universal sd-shell interaction A (USDA) is used for sd-shell orbits. Two models have been used to calculate core-polarization (CP) effects. These models are Coulomb Valance Tassie model (CVTM) and Bohr–Mottelson (BM) collective model. The wave functions of radial single particle matrix elements have been calculated with Skyrme interaction potential (SKX). Electron scattering factors results showed good agreement using the BM collective model comparing with the experimental data.

Determination of hexadecapole (β4) deformation of the light-mass nucleus 24Mg using quasi-elastic scattering measurements

Quasi-elastic scattering measurements have been performed using 16O and 24Mg projectiles off 90Zr at energies around the Coulomb barrier. Experimental data have been analyzed in the framework of coupled channels (CC) calculations using the code CCFULL. The quasi-elastic scattering excitation function and derived barrier distribution for 16O + 90Zr reaction are well reproduced by the CC calculations using the vibrational coupling strengths for 90Zr reported in the literature. Using these vibrational coupling strengths, a Bayesian analysis is carried out for 24Mg + 90Zr reaction. The β2 and β4 values for 24Mg are determined to be +0.43±0.02 and −0.11±0.02, respectively. The β2 parameter determined in the present work is in good agreement with results obtained using inelastic scattering probes. The hexadecapole deformation of 24Mg has been measured very precisely for the first time. Present results establish that quasi-elastic scattering could provide a useful probe to determine the ground state deformation of atomic nuclei.

Spectral fluctuations in 24Mg nucleus using the framework of the nuclear shell model

Random matrix theory is used to study the chaotic properties in nuclear energy spectrum of the 24Mg nucleus. The excitation energies (which are the main object of this study) are obtained via performing shell model calculations using the OXBASH computer code together with an effective interaction of Wildenthal (W) in the isospin formalism. The 24Mg nucleus is assumed to have an inert 16O core with 8 nucleons (4protons and 4neutrons) move in the 1d5/2, 2s1/2 and 1d3/2 orbitals. The spectral fluctuations are studied by two statistical measures: the nearest neighbor level spacing distribution P(s) and the Dyson-Mehta statistics (∆3 statistics). For calculations with the full diagonalization of the Hamiltonian, the spectral fluctuations are found to be in agreement with the Gaussian orthogonal ensemble of random matrices.

A analysis of 16O+α+α cluster model of 24Mg from elastic electron scattering

A simple cluster model of 16O+α+α structure for a 24Mg nucleus has been analyzed by fitting the experimental data of elastic electron scattering in the PWBA and DWBA approaches. The information on the relative motion of the α+α system and (α+α)+16O system are obtained. The calculated results show a prolate deformed configuration of the type α+16O+α for the 24Mg ground state.

The Magnetic Isotopes Effect of Magnesium 25Mg on the Physiological Properties of Bacteria E. coli

Magnetic isotope effects of magnesium 25Mg on antibiotic resistance and biofilm formation of bacteria E. coli were discovered. The increase in antibiotic resistance in the presence of the ion 25Mg2+ was registered for E. coli cells incubated with quinolones, indicating the inhibiting effect of the magnetic moments of nuclei 25Mg on deoxyribonucleic acid (DNA) synthesis. It was discovered that the process of biofilm formation by the bacteria E. coli is magnetosensitive. Magnetic magnesium isotope presence in nutrient media stimulated formation of biofilm compared with nonmagnetic isotopes 24, 26Mg. As e result the enrichment of media by magnetic magnesium can be used to control the physiological properties of bacteria: biofilm formation and antibiotic resistance.

One-body density matrix and momentum distribution in s-p and s-d shell nuclei

Analytical expressions of the one- and two- body terms in the cluster expansion of the one-body density matrix and momentum distribution of the s-p and s-d shell nuclei with Ν — Ζ are derived. They depend on the harmonic oscillator parameter b and the parameter β which originates from the Jastrow correlation function. These parameters have been determined .by least squares fit to the experimental charge form factors. The inclusion of short-range correlations increases the high momentum component of the momentum distribution, 7i(k) for all nuclei we have considered while there is an A dependence of ra(k) both at small values of k and the high momentum component. The A dependence of the high momentum com- . ponent of n(k) becomes quite small when the nuclei 24Mg, 28Si and 32S are treated as ld-2s shell nuclei having the occupation probability of the 2s-state as an extra free parameter in the fit to the form factors

Electromagnetic multipole of positive and negative parity states in 24Mg by elastic and inelastic electron scattering

In the present work, the nuclear shell model with Hartree–Fock (HF) calculations have been used to investigate the nuclear structure of 24Mg nucleus. Particularly, elastic and inelastic electron scattering form factors and transition probabilities have been calculated for low-lying positive and negative states. The sd and sdpf shell model spaces have been used to calculate the one-body density matrix elements (OBDM) for positive and negative parity states respectively. Skyrme-Hartree-Fock (SHF) with different parameterizations has been tested with shell model calculation as a single particle potential for reproducing the experimental data along with a harmonic oscillator (HO) and Woods-Saxon (WS) single-particle potentials. The effect of the nuclear effective charge has been implemented via using different folding models; valance, Tassie and Bohr-Mottelson. The evaluated results have been discussed and compared with available experimental data.

Shape isomers of light nuclei from the stability and consistency of the SU(3) symmetry

We investigate the stability and self-consistency of the SU(3) symmetry and quadrupole deformation in light nuclei in terms of the Nilsson model and quasi-dynamical symmetry. It turns out that SU(3) is a remarkably good symmetry for commensurable major axes, similarly to the finding of the simple harmonic oscillator interaction. The method serves as an alternative to the well-known energy-minimum calculation for the determination of the shape isomers. In case of the 16O, 20Ne, and 24Mg nuclei the results of the two different procedures are in good agreement with each other.

Polarization Features of the 24Mg(2+) Nucleus Produced in the Reaction 27Al(p, α)24Mg(2+)

At the proton energy of Ep = 7.4 MeV, the double-differential cross sections for the reaction 27Al(p, α1γ)24Mg were measured for 11 values of the alpha-particle emission angle in the range of θα = 30°–160°(lab). All even components of the density-matrix spin-tensors were reconstructed for the oriented 24Mg nucleus in the 2+ state at 1.369 MeV, and the polarization features of this nucleus, including the populations of magnetic sublevels of the nucleus for all spin projections, multipole-moment orientation tensors, and the quadrupole and hexadecapole tensor polarizations, were determined. Relevant experimental results were compared with their counterparts calculated for the triton-pickup mechanism within the coupled-channel method and in the statistical limit of the compound-nucleus model.

Role of the Mechanism of Heavy Cluster Stripping in a 27Al(р, α)24Mg Reaction

The contribution from the mechanism of heavy 23Na cluster stripping from a 27Al(5/2+) initial nucleus to a cross section of the 27Al(р, α)24Mg(0+, 2+) reaction is calculated at Ep = 7.4 MeV and angles of α‑particle emission of 25°–160° (laboratory). Calculations are made with the FRESCO code using the contribution from the 3/2+ ground state of 23Na. Spectroscopic amplitudes at decay vertices of 27Al(5/2+) → 23Na(3/2+) + α and 24Mg(0+, 2+) → 23Na(3/2+) + р reactions are determined from wave functions in the context of the Nilsson model, depending on their deformation. Cross sections calculated for the 0+ and 2+ levels of the 24Mg nucleus are two orders of magnitude lower than those found experimentally. The cross section for the 0+ level grows at θα ∼ 180° in the back semi-sphere, while the one for the 2+ level exhibits a maximum at θα > 140°. The slight contribution from the mechanism of heavy cluster stripping is due to the spectroscopic amplitudes at the decay vertices of the initial and final nuclei owing to a weak overlap of wave functions of 27Al, 23Na, and 24Mg(0+, 2+) nuclei in the Nilsson model.

Nuclear magnetic moment studies of short–lived excited states at the edge of the island of inversion: the IS628 experiment

Nuclear gfactors are highly sensitive to the single–particle aspects of the wave function, revealing important information for the nuclear structure along the isotopic chart. The sdshell has been thoroughly studied, resulting in “universal” shell model Hamiltonians [1] and the development of an M1 operator [2]. However, there is still shortage of precise experimental gfactor data of excited states to consolidate the nuclear structure in this regime. Recently, the Time Differential Recoil in Vacuum (TDRIV) experimental technique was revamped to be applicable for radioactive beams. TDRIV has been tested successfully and produced high-precision results for the stable 24Mg nucleus [3]. However, the successful application of the technique relies heavily on calibrations of the de–orientation phenomenon. A recent experiment using the MINIBALL array at REX/ISOLDE (IS628) has focused on the application of the method with a radioactive 28Mg beam. The gfactor of the 28Mg first 2+excited state can act as an excellent probe of the N=16 shell gap and the νd3/2singleparticle energy, as well as the possible presence of spdfadmixtures. The particular measurement will be a next step towards a gfactor measurement on 32Mg in the center of the “island of inversion”, where the N=20 shell closure breaks down enhancing 1p–1h excitations and shape–coexistence. In this work, the analysis of the spectroscopic data recorded for a 22Ne beam, which was used for calibrating the experimental method before the actual run on 28Mg is reported. Preliminary data on the angular distributions for the 22Ne 21+→ 0+transition will be presented, an important prerequisite before a remeasurement of g(22Ne;21+).

Charge density distributions and electron scattering form factors of 19F, 27Al and 25Mg nuclei

An effective two-body density operator for point nucleon system folded with two-body correlation functions, which take account of the effect of the strong short range repulsion and the strong tensor force in the nucleon-nucleon forces, is produced and used to derive an explicit form for ground state two-body charge density distributions (2BCDD's) and elastic electron scattering form factors F (q) for 19F, 27Al and 25Mg nuclei. It is found that the inclusion of the two-body short range correlations (SRC) has the feature of reducing the central part of the 2BCDD's significantly and increasing the tail part of them slightly, i.e. it tends to increase the probability of transferring the protons from the central region of the nucleus towards its surface and to increase the root mean square charge radius ˂ r 2˃ 1/2 of the nucleus and then makes the nucleus to be less rigid than the case when there is no (SRC). It is also found that the effects of two body tensor correlations (TCs) on 2BCDD's and ˂ r 2˃ 1/2 are in opposite direction to those of (SRC).

Calculating Energy Levels in 25Mg/25Al Mirror Nuclei


 
 
 
 Coulomb Displacement Energies in mirror nuclei 25Mg, 25Al have been calculated using shell model code OXBASH [1] and compared with experimental results. The code calculations were done in the USD model space with the W Hamiltonian [2]. The OXBASH code which is based on famous nuclear model, the shell model, deals with evaluating energy levels in nuclei. A comparison had been made between our results and the available experimental data [3] to test theoretical shell model description of nuclear structure in mirror nuclei. The energy states of mirror nuclei are almost identical, except for the small effects due to Coulomb interaction where the symmetry in being broken. Energy spectrum calculated with this code was in good agreement with the published experimental data [3].