https://ijpr.iut.ac.ir/ Iranian Journal of Physics Research en daily 1 Sun, 23 Aug 2026 00:00:00 +0330 Sun, 23 Aug 2026 00:00:00 +0330 https://ijpr.iut.ac.ir/article_3817.html Mass loss from evolved stars, particularly long-period variable stars (LPVs), plays a critical role in enriching the interstellar medium and contributing to galactic evolution. This study investigates the mass-loss rates of LPVs in the irregular dwarf galaxy NGC 6822 using infrared data from ground-based telescopes in the wavelength range of 1.2 to 2.2 micrometers and data from the Spitzer Space Telescope at 3.6 and 4.5 micrometers. By deriving the spectral energy distributions of these stars and analyzing their radiative properties, the overall mass-loss rates of carbon-rich and oxygen-rich stars were determined. The results indicate a total mass-loss rate from LPVs of approximately 2.7 × 10⁻⁵ M☉ yr⁻¹, with dust production contributing roughly 3.7 × 10⁻⁹ M☉ yr⁻¹, while the remainder is attributed to ejected gas. Furthermore, oxygen-rich and carbon-rich stars contribute 22% and 78%, respectively, to the total mass loss of LPVs. Given the low metallicity of this galaxy, the dominant role of carbon-rich stars in the production of interstellar dust is expected. Considering the estimated current star formation rate in the bar region of NGC 6822, reported as 1.7 × 10⁻² M☉ yr⁻¹, the findings suggest that the mass returned by LPVs is insufficient to provide the interstellar material required to sustain ongoing star formation in this galaxy. https://ijpr.iut.ac.ir/article_3816.html Driven out-of-equilibrium systems exhibit richer topological phases compared to time-independent counterparts. In particular, when the time dependence is periodic, systems manifest topological phases that have not been observed in equilibrium systems. In this paper, we examine topological phase transitions in the extended Kitaev model with the periodically time-dependent chemical potential. First, we analyze the phase diagram of the system in equilibrium case, and then we show that driving the system with a periodically time-dependent chemical potential affects its topological phases and the energy spectrum of the model, thereby altering its phase diagram. https://ijpr.iut.ac.ir/article_3818.html The effect of target geometry on magnetic field amplification in high-intensity laser–plasma interactions is investigated using two-dimensional particle-in-cell (PIC) simulations performed with the EPOCH code. Two plasma target configurations are considered: a double-cone target and a curved-foil target, while all laser parameters, computational conditions, and plasma properties are kept the same. The temporal evolution and spatial distribution of the generated magnetic field, particle energies, and electric-field components are analyzed. The results show that the curved-foil target produces a stronger, more localized, and more temporally stable magnetic field than the double-cone target. This enhancement is associated with improved electron confinement, increased axial current density, and reduced radial electron divergence. The findings demonstrate that target geometry plays an important role in controlling current dynamics and enhancing magnetic field generation in laser–plasma interactions. https://ijpr.iut.ac.ir/article_3819.html Given the increasing development of plasma technology and its wide range of applications in various research and industrial fields, investigating the physical and chemical properties of plasmas produced under different gas compositions is of particular importance. In this study, we evaluate the physical and chemical properties of an argon–oxygen gas mixture by simulating a dielectric barrier discharge at a pressure of 400 Pa under a sinusoidal voltage with an amplitude of 350 V and a frequency of 7 kHz. Argon was considered as the base gas, and oxygen was added at five different concentrations of 1%, 5%, 10%, 20%, and 50%. The simulations were performed using the commercial software COMSOL Multiphysics, and parameters such as the voltage–current characteristic, density distributions of different species, and electron temperature distribution were investigated. The aim of this study is to investigate the temporal evolution of the kinetic properties and densities of various generated species, such as ozone and atomic oxygen, which play an important role in sterilization processes, and to determine their optimal values for improving the efficiency of the system. https://ijpr.iut.ac.ir/article_3828.html In this work, Krylov complexity is investigated within the framework of quantum field theory as a diagnostic for characterizing the growth and spreading of operators in quantum systems. The focus is on a nonrelativistic fermionic field defined on a half-line rather than an unbounded space, such that the presence of a boundary plays a decisive role in the system’s evolution. We first review the structure of thermal Wightman functions and the momentum-mode expansion of the Schrödinger field on the full line in order to establish the computational framework required to define the spectrum, the thermal inner product, and the relevant correlation functions. We then impose Robin boundary conditions and demonstrate how reflection from the boundary modifies the structure of the correlation functions and, consequently, the quantities governing operator growth. The limiting behaviors corresponding to a transparent boundary and a fully reflecting boundary are also analyzed to clarify under which conditions the half-line effectively reproduces the full-line results and under which conditions it leads to a significant modification of complexity growth. Our numerical results show that, depending on the physical parameters of the system, the boundary can either suppress or enhance the growth rate of complexity, thereby acting as a controlling factor in the dynamical evolution of Krylov complexity. https://ijpr.iut.ac.ir/article_3820.html Ensuring access to clean water necessitates effective wastewater treatment strategies, particularly through advanced photocatalytic methods. In this study, polyacrylonitrile (PAN) nanofibers were fabricated by electrospinning as a low-cost and scalable substrate to support the growth of ZnO nanorods (NRs). Subsequently, silver nanoparticles (Ag NPs) were uniformly deposited onto the ZnO NRs/ PAN NFs to synthesize Ag NPs/ ZnO NRs/ PAN NFs composites with an optimized silver content. The photocatalytic performance of the prepared nanocomposites was evaluated by monitoring the degradation of Acid Orange 7 (AO7) dye and a mixture of methylene blue (MB) and rhodamine B (RhB) as model organic pollutants under UV and natural sunlight irradiation, respectively. The Ag NPs/ ZnO NRs/ PAN NFs exhibited a 1.7 times higher photocatalytic activity for AO7 photodegradation under UV light compared to the ZnO NRs/ PAN NFs. Additionally, under natural sunlight, this composite achieved photodegradation efficiencies of 83.5% and 60.4% for mixture of MB and RhB within 60 minutes, respectively. Mechanistic investigations using radical scavengers confirmed that the generation of hot plasmonic electrons on the Ag NPs under UV illumination plays a crucial role in enhancing photocatalytic performance. Owing to its flexibility and mechanical integrity, this photocatalyst presents a promising platform for future research and practical applications in efficient wastewater treatment. https://ijpr.iut.ac.ir/article_3781.html Surface dielectric barrier discharge (SDBD) plasma is a novel non-thermal technology capable of generating reactive oxygen and nitrogen species at atmospheric pressure without the need for noble gases in food packaging. In this study, pistachio kernel samples contaminated with Aspergillus flavus spores were treated with SDBD plasma at a voltage of 6.8 kV and a frequency of 7.4 kHz for 10, 20, and 30 min using air as the working gas inside the packaging. The reduction in microbial load and the physical characteristics of the plasma, including the current-voltage characteristics, were investigated, and the plasma power was calculated. Optical emission spectroscopy (OES) was used to identify the active species generated in the plasma. In addition, ozone and reactive nitrogen species (NOx) production was measured, and changes in surface morphology (FESEM), weight loss, and sensory and color parameters were evaluated. OES analysis confirmed the presence of reactive species, including excited nitrogen (*N₂), hydroxyl radicals (•OH), and atomic oxygen (O). Treatment for 30 min resulted in a 4-log reduction (99 %) in the population of A. flavus spores. FESEM images showed complete destruction of the spore cell wall and depletion of the spore cytoplasm after 30 min of treatment. Sensory evaluation using a 9-point hedonic scale showed that treatment for up to 10 min had no adverse effect on the sensory properties of pistachio kernels. However, increasing the treatment time to 20 and 30 min, while maintaining the odor and taste of the product, resulted in a significant decrease in color scores. With its effective sterilization capability, low cost, and preservation of sensory quality at shorter treatment times, SDBD technology represents a promising method for enhancing the safety and shelf life of pistachios and other agricultural products. https://ijpr.iut.ac.ir/article_3779.html We show that the AdS2 metric in the presence of a Maxwell field together with a constant dilaton field satisfies the equations of motion of the heterotic string theory. Then, by applying non-Abelian T-duality (here, Poisson-Lie T-duality on a semi-Abelian double), a non-Abelian dual pair for the AdS2 metric is constructed. By using a certain parametrization of the two-dimensional non-Abelian Lie group A2 we construct the original sigma model, which includes the AdS2 metric in the absence of a B-field. It is shown that the dual background constructed by means of the Poisson-Lie T-duality is supported by a B-field and a metric that contains a true singularity. By examining the behavior of the dual metric in the region r=0, it is shown that the metric along with a non-trivial dilaton field and an appropriate Maxwell field satisfy the equations of motion of the heterotic string theory for very small r. Most interestingly, for large r, the dual metric approaches the asymptotic solution; in fact, the dual metric is asymptotically AdS2. Finally, we discuss D-branes and the worldsheet boundary conditions defined by a gluing matrix on the AdS2 sigma model. Using the duality map obtained from the canonical transformation description of the Poisson-Lie T-duality for the gluing matrix, which locally defines the properties of the D-brane, we find three different cases of the gluing matrices for the AdS2 sigma model and its dual pair. https://ijpr.iut.ac.ir/article_3821.html This research focuses on a comprehensive investigation of the thermal behavior and resulting mechanical effects in an electron gun utilized in a linear accelerator operating at an energy of 6 MeV. The test cathode was heated under near-operating vacuum conditions (10−5mbar) up to an operational temperature of 1050∘C. The resulting temperature distribution was measured using both thermocouples and a non-contact pyrometer. The experimental results obtained at various power levels served as the basis for validating the numerical modeling conducted with COMSOL Multiphysics software; the accuracy of the thermal simulation was confirmed through close agreement between the simulation and experimental results. Subsequently, thermo-mechanical analyses were performed based on the thermal data, and the geometry of the components was optimized to reduce stresses induced by thermal deformation within the ceramic body. The most critical aspect of this work involved examining the thermal effects on the geometrical dimensions of the cathode and their influence on the characteristics of the output electron beam , which was modeled using CST software. By comparing the output beam in the cold state and the hot state, the cathode dimensions were adjusted such that the hot dimensions matched the cold dimensions. This dimensional optimization ensured that the resulting electron beam under various operating conditions remained consistent with the design specifications of the reference (cold) state. This empirically validated approach guarantees the high-power performance efficiency of the electron gun. https://ijpr.iut.ac.ir/article_3822.html Today, online gamma-ray dosimetry is one of the most widely used approaches for radiation dose measurement. One of the most comprehensive dosimetry methods is the direct conversion of the recorded gamma-ray energy spectrum into dose, or, in other words, the conversion of a spectrometer into a dosimeter. Among the numerous methods for converting a spectrometer into a dosimeter, the G(E) function method is considered one of the most suitable and accurate methods due to its use of energy-dependent conversion coefficients. In this study, the MCNP6 simulation code and a 2×2-inch NaI(Tl) spectrometer were used to calculate equivalent dose based on the recorded spectrum. Based on the equivalent-dose measurement conditions for a directional extended source, the novelty of this work is the development of a practical and efficient method for calibrating a point-source-based dosimeter in the laboratory, allowing valid equivalent-dose results to be obtained without the need to place the dosimeter in the radiation field of a directional extended calibration source. https://ijpr.iut.ac.ir/article_3823.html In this paper, a metal-insulator-metal (MIM) metasurface is proposed and the influence of various parameters on its absorption properties is investigated. This metasurface shows broadband perfect absorbtion of electromagnetic wave in the near infrared spectral region. The nanoantennas consist of two different gold rectangular bars in a unit cell. The most bottom layer is made of Au, and the middle spacer is a dielectric material. Numerical simulations based on the finite element method (FEM) show that by tuning the geometrical parameters of the cross-shape, such as the rotation angle and displacement of one of the bars, and also tuning the thickness of middle spacer, one can achieve more than 97% to 99.8% absorbtion over a 330 banwidth, with correspondingly negligible reflectance. The near perfect absorption results from the destructive interference of succesive internal reflections within the spacer and impedance matching between the metasurface and vacuum. This metasurface can be used as an infrared sensor and a perfect absorber. https://ijpr.iut.ac.ir/article_3824.html In the present work, the effects of projectile charge and velocity on determining the dynamics of the single ionization process of a helium atom from its ground state have been investigated. For this purpose, H+, C6+, Au53+ and U 93+ ions have been used as the projectiles. In these calculations, the four-body continuum distorted wave formalism in the post form is used. The Silverman wave function as the ground state of helium atom has been used to consider the effects of static electron correlation. The fully differential cross section for each projectile in the scattering plane, for the various ejected electron energies and momentum transfers, are compared with the available experimental and theoretical results. https://ijpr.iut.ac.ir/article_3825.html Terahertz (THz) radiation generation through two-color femtosecond pulse filamentation has become a standard method in ultrafast optics due to its broadband nature and high intensity. However, achieving precise control over the temporal characteristics of this radiation at the sub-picosecond scale—which is vital for applications such as time-domain spectroscopy and coherent control of light-matter interactions—remains a fundamental challenge. In this article, a novel approach is presented for engineering the waveform of emitted terahertz radiation by redesigning the temporal profiles of the input optical pulses and employing a dual pulse excitation scheme. Using the “photocurrent” model, the effect of temporal interference between plasma currents generated by the combination of Gaussian pulses with different time delays was investigated. Numerical results show that, by carefully adjusting the pulse intensities to avoid premature saturation of ionization, a stepwise evolution of the plasma density can be induced, which in turn leads to shaping of the net photocurrent. The findings indicate that for time delays shorter than the current relaxation time, constructive or destructive interference between currents enables selective control of certain field half-cycles and the generation of novel temporal profiles. In contrast, for delays longer than the current decay time, the terahertz pulses form separately as multi-component waveforms. These results outline a new pathway for developing tunable terahertz sources and their applications in ultrafast dynamical studies. https://ijpr.iut.ac.ir/article_3826.html In this paper, a quantum chromodynamics-based analysis is presented to determine the proton parton distribution functions in the second order of the Feynman diagram. This analysis uses a large and combined experimental dataset including deep inelastic scattering data from the HERA and BCDMS experiments, non-LHC hadron collider data including jet production cross sections from the tevatron experiments, and LHC data, especially jet production and heavy quark production cross sections. These data provide accurate coverage in the small fractional momentum region and provide valuable information about the proton flavor structure. In the first step, the free proton parton distribution functions were extracted by fitting to these data. Then, by generalizing these functions to the nuclear environment and using experimental data related to nuclei, the nuclear parton distribution functions are calculated. The EMC effect is subsequently investigated quantitatively, and the results are compared with those obtained by other global analyses. This comprehensive analysis shows good agreement with experimental data and provides a more detailed understanding of the partonic structure of the proton in free and bound states. https://ijpr.iut.ac.ir/article_3829.html Magnetic reconnection and plasmoid instability, which occur in magnetized plasmas such as the solar corona plasma, are important mechanisms for accelerating charged particles and enhancing the conversion of magnetic energy into thermal and kinetic energy. In this study, using two-dimensional particle-in-cell simulation of magnetic reconnection and plasmoid instability, the role of the initial magnetic field in the acceleration of charged particles in the solar corona plasma is investigated through the energy distribution function of charged particles. When the magnitude of the initial magnetic field does not satisfy the condition for the formation of plasmoid instability, the system remains in the initial magnetic reconnection state and the energy distribution function shows that at low energies, the bulk energy of the plasma increases with time, but the particles cannot reach higher energies. However, in plasmoid instability, where multiple reconnection points exist, the energy distribution function shows that charged particles accelerated to relativistic energies. In the plasmoid instability, due to the presence of multiple magnetic reconnections and also the existence of wave–particle interaction, the acceleration of charged particles is more efficient. https://ijpr.iut.ac.ir/article_3830.html Silicon nanoclusters, as intermediate structures between molecules and bulk silicon, provide a unique platform for studying size-dependent transitions in structural, electronic, and magnetic properties. In contrast to bulk crystalline silicon, which is weakly diamagnetic, silicon clusters may exhibit a temperature-dependent paramagnetic response and interesting behavior due to dominant surface effects, quantum confinement, surface reconstruction, and the dangling bonds. Being highly sensitive to the density of electronic states near the Fermi level, accurate determination of the Fermi level plays a key role in predicting magnetic susceptibility. We present a computational framework in which atom-projected density of states is predicted using machine learning, while a local chemical potential is assigned to each atom based on the equilibrium charge distribution. By combining these two ingredients, we obtain a single-particle approximation of the magnetic susceptibility of individual atoms. For pure silicon nanoclusters, we show that the contribution of surface atoms to the magnetic response is significantly larger than that of interior atoms. The overall magnetic susceptibility of the particle decreases with increasing nanocluster diameter and approaches the bulk value. This result is consistent with the general behavior of nanoparticles and merits further experimental investigation or the development of models that go beyond the present framework by incorporating spin interactions and exchange (Stoner) enhancement. https://ijpr.iut.ac.ir/article_3831.html Many decay or scattering processes in particle physics involve the production of partons in the final state. Except for the Top quark, which decays rapidly due to its very short lifetime, all other partons are converted into observable hadrons through a non-perturbative process. The factorization theorem in Quantum Chromodynamics (QCD) enables us to separate the perturbative and nonperturbative sectors of a hadronic process at a hard energy scale. This factorization makes it possible to theoretically calculate some experimental quantities such as cross sections and decay rates. In conventional factorization theorems, the masses of quarks as well as those of final-state hadrons are commonly neglected. In the present work, we intend to prove a generalized form of this theorem in the presence of quark and hadron masses for hadron production in a decay process. Then, as an applied example, we study the effect of mass on the energy distribution of the produced mesons resulting from the decay of the Higgs boson. We will show that the effect of meson mass is very important at low energies and can change the results by up to 45%. https://ijpr.iut.ac.ir/article_3832.html We study several aspects of symmetry resolved capacity of entanglement in certain nonrelativistic quantum field theories which are scale invariant. In particular, we focus on scalar theories with nontrivial dynamical exponent. This study aims to develop a deeper understanding of how each symmetry sector contributes to the capacity of entanglement of the corresponding ground state. Using the correlator method, we compute symmetry-resolved capacity of entanglement and analyze its dependence on the charge and the dynamical exponent. Our results reveal that in these theories, approximate equipartition of entanglement among charge sectors emerges in the large-z regime. https://ijpr.iut.ac.ir/article_3833.html Plasma photonic crystals are structures in which dielectric materials and plasma are arranged periodically. Owing to its characteristic plasma frequency and Debye length, plasma strongly influences the behavior of electromagnetic waves. In the analysis of wave propagation in plasma, the inclusion of collisions is essential, since real plasmas always involve electron–ion and electron–neutral interactions. These collisions are the primary source of the effective resistance of electrons against field oscillations and therefore determine how much of the wave energy is transmitted, absorbed, or reflected by the plasma. In this paper, wave transmission through one-dimensional photonic structures consisting of dielectric layers and a plasma defect layer is investigated using the transfer matrix method and detailed numerical simulations. The simulation results show that increasing the plasma density shifts the defect modes toward higher frequencies, whereas increasing the thickness of the plasma layer shifts them toward lower frequencies. Moreover, increasing the electron collision frequency leads to wave damping, a reduction in transmission intensity, and a broadening of the resonant peaks. Precise control of plasma parameters and photonic structure design provides a powerful tool for realizing filters and sensors with tunable resonant characteristics. https://ijpr.iut.ac.ir/article_3834.html In this paper, the structure of neutron star crusts is investigated within the framework of a holographic model based on the gauge-gravity duality. The focus of this study is the description of dense nuclear matter in the transition region between the uniform phase and the vacuum. A key objective is the analysis of inhomogeneous phases in the form of various geometric configurations in the mixed region. For this purpose, the Witten-Sakai-Sugimoto model is employed as an effective QCD model at low energies. By calculating the free energy and comparing the thermodynamic stability of different geometric configurations, the region in which the mixed phase emerges along with its corresponding structures, is determined. The results indicate that rod-like structures remain stable over a broader range of chemical potentials and play a more significant role in determining the crust thickness. Furthermore, the dependence of free energy on the surface tension coefficient reveals that this parameter acts as a controlling factor in the stability of inhomogeneous phases, and its increase leads to a reduction in the preferred region for geometric configurations. These findings provide a coherent picture of the role of geometric structures in determining the thermodynamic properties of neutron star crusts within the holographic framework. https://ijpr.iut.ac.ir/article_3539.html This work investigates the behavior of Shannon entropy and Fisher information for the Varshni-Hellmann potential (VHP) in one and three dimensions using the Nikiforov-Uvarov method. We employ the Greene-Aldrich approximation scheme to obtain the energy eigenvalues and normalized wavefunctions, which are then used to calculate these information-theoretic quantities. Our analysis revealed remarkably similar high-order features in both position and momentum spaces. Notably, our calculations showed enhanced accuracy in predicting particle localization within position space. Furthermore, the combined position and momentum entropies obeyed the lower and upper bounds established by the Berkner-Bialynicki-Birula-Mycieslki inequality. Additionally, for three-dimensional systems, the Stam-Cramer-Rao inequalities were fulfilled for different eigenstates with respect to the calculated Fisher information. It is observed that as the position Fisher entropy decreases, indicating a more precise measurement of position, the momentum Fisher entropy must increase. This implies that the Fisher information regarding momentum decreases, resulting in a decrease in the precision of momentum measurement. This demonstrates how position and momentum uncertainties complement each other in quantum mechanics. Exploring the balance between position and momentum Fisher entropy reveals a fundamental aspect of the uncertainty principle in quantum mechanics, highlighting the restrictions on measuring certain pairs of conjugate variables simultaneously with high precision. https://ijpr.iut.ac.ir/article_3780.html In this research, the thermoelectric properties of two-dimensional Y₂CX₂ (X = F, Cl, Br, I, and O) structures have been investigated using semi-classical Boltzmann theory within the constant relaxation time approximation (CRTA) framework. These structures have been previously validated for structural, thermodynamic, dynamic, and mechanical stability, and their electronic, optical, and photovoltaic properties have been reported. In this study, key thermoelectric parameters were calculated and analyzed in the temperature range of 0 to 1000 K. Based on the obtained results, Y₂CCl₂ and Y₂CF₂ structures exhibit the highest thermoelectric performance with ZT values of approximately 0.578 and 0.410 at 300 K, respectively, demonstrating competitive performance compared to well-known materials such as MoS₂ (0.11), Ti₃C₂Tₓ (0.22), and Bi₂Te₃ (0.80). The comprehensive analysis of these results highlights the high potential of the Y₂CX₂ family of MXenes for converting thermal energy into electricity, particularly at high temperatures.