https://ijpr.iut.ac.ir/ Iranian Journal of Physics Research en daily 1 Fri, 20 Feb 2026 00:00:00 +0330 Fri, 20 Feb 2026 00:00:00 +0330 https://ijpr.iut.ac.ir/article_3746.html This paper presents a comprehensive semi-analytical approach to the temporal evolution and final abundance of light elements 7Be  formed during Big Bang nucleosynthesis. By systematically examining the fundamental processes, we reveal the complex physics involved in the formation of these primordial elements. Our findings not only enhance the understanding of nucleosynthesis dynamics but also provide valuable insights into the conditions of the early universe and emphasize the importance of light elements in cosmic evolution. One of the most significant results of this paper is the derivation of semi-analytical relations for the final abundance of light elements as a function of the normalized baryon-to-photon ratio (η_10). In the end, the acceptable range of the parameter  η_10 is discussed through a comparison of observational results. https://ijpr.iut.ac.ir/article_3701.html This study investigates the dosimetric properties of alumina-based phosphor doped with dispersium impurity, evaluating its potential as highly sensitive thermoluminescent material for high-dose applications. All samples were synthesized using the sol-gel method. The highest sensitivity to gamma radiation from a 60Co source was observed in the sample with 0.5 mol% dispersium doping. The structural and morphological properties of the particles were examined using X-ray diffraction (XRD) and scanning electron microscopy (SEM), while elemental analysis of the α-alumina sample was analyzed using energy-dispersive X-ray spectroscopy (EDS). The kinetic parameters of the thermoluminescence (TL) glow curve were extracted through computer-based curve fitting. The TL glow curve exhibited two overlapping peaks at approximately 394 K and 449 K. Additional analyses of the glow curve characteristics, fading characteristics, and dose-response linearity demonstrated the strong potential of this nanophosphor as a high-sensitivity TL dosimeter suitable for high-dose radiation measurements. https://ijpr.iut.ac.ir/article_3747.html In the present work, the effect of  Lambda(1405) resonant state on the neutrons momentum and energy spectra due to a stopped kaon on deuteron is studied within the coupled-channel approach, employing Argonne V18SC potential to describe nucleon-nucleon interaction. For this purpose, both chiral and phenomenological potentials with different one-pole and two-pole structures have been used to investigate the dependence of the neutrons spectrum resulting from the interaction on the different models. In the following, using the Akaishi-Yamazaki model, we have shown that the Lambda(1405) resonance trace is clearly visible in such spectra. Our results indicate that a detailed study of the kaon–deuteron interaction can significantly contribute to improving our understanding of the KN-πƩ interaction and the nature of theresonance. https://ijpr.iut.ac.ir/article_3748.html The spectral form factor (SFF) is a widely used tool for diagnosing quantum chaos and information scrambling. Recent studies have shown that the SFF can also indicate scrambling behavior in integrable systems when non-local random couplings are present. In this work, we investigate integrable bosonic systems governed by quadratic Hamiltonians with local random interactions. Through numerical analysis, we demonstrate that the SFF exhibits a ramp at intermediate times, a feature absent in integrable systems without randomness. The presence of this ramp provides evidence supporting the notion of quantum information scrambling in locally coupled, yet integrable, systems. https://ijpr.iut.ac.ir/article_3749.html In this paper, we investigate the spin and valley transport of electrons through a ferromagnet-normal-ferromagnet junction in a 8-pmmn borophene monolayer. A gate voltage is applied to the normal region and an exchange magnetic field is applied to both sides of this region through the ferromagnetic substrate. The exchange field breaks the spin degeneracy and results in spin polarization. On the other hand, the gate voltage induces valley polarization in the system. The valley polarization induced by the gate voltage is due to the presence of tilted and anisotropic Dirac cones in the borophene structure. While in materials such as graphene with isotropic cones, the gate voltage cannot induce valley polarization and strain must be applied to the system. Our proposed system can act as a perfect valley and spin filter such that the filtration characteristic can be controlled by changing the Fermi energy and gate voltage. It is observed that if the length of the normal region is greater than a certain limit, perfect valley polarization occurs. According to the results, this system can be used in borophene-based electronic and spintronic devices. The investigation of magnetoresistance is another study that has been conducted, and indicates the potential capability of this material in the fabrication of spin memories. https://ijpr.iut.ac.ir/article_3702.html One of the most significant properties of metals is their ability to undergo phase transformations and structural changes in response to external forces, temperature variations, and other environmental factors. In this study, molecular dynamics (MD) simulations are employed to investigate phase transformation mechanisms and deformation behavior in a pristine and defect-free α-Fe specimen subjected to high strain rate tensile loading. The results reveal that, during the loading process, the microstructural transformation initiates from a body-centered cubic (bcc) structure to a face-centered cubic (fcc) structure, followed by a subsequent transition from fcc to a hexagonal close-packed (hcp) configuration. Furthermore, the critical stress levels follow the order  stress(hcp)>stress(fcc)>stress(unknown)>stress(bcc), indicating that the hcp structure requires the highest stress to initiate transformation. Consequently, bond rupture and fracture nucleation are most likely to occur in the vicinity of this phase. https://ijpr.iut.ac.ir/article_3750.html In this study, the optical response of plasmon–exciton–plasmon (PEP) hybrid structures was investigated using the finite-difference time-domain (FDTD) simulation method. The structures were composed of disk-shaped metallic nanoparticles made of silver and gold, combined with molecular excitons originating from J-aggregated cyanine dyes. As an initial step, the extinction spectra of the individual metallic components and dye molecules were analyzed separately to identify the intrinsic resonance characteristics of each component. Subsequently, the influence of structural parameter variations on the coupling strength between the constituents was evaluated. The resulting spectra exhibited three distinct hybrid branches, namely the lower (L), middle (M), and upper (U) branches, indicating the interaction between the fundamental plasmonic and excitonic modes. By tracking the variations in detuning frequency, the coupling pathways between the plasmonic and excitonic resonances were identified.The results clearly demonstrate the pivotal role of nanoparticle size and detuning in Rabi splitting and the anti-crossing behavior of the hybrid modes. This study provides a comprehensive framework for spectral engineering of PEP hybrid structures and highlights their high potential for developing advanced nanophotonic devices and PEP-based biosensors. https://ijpr.iut.ac.ir/article_3711.html In this paper a graphene-based metasurface is designed and analyzed to operate as an electromagnetic wave absorber in the terahertz frequency range. The proposed geometrical structure consists of a graphene ring with four slits in each unit cell, arranged in a two-dimensional array on a dielectric substrate. Simulation results obtained using the finite element method (FEM) demonstrate that, by tuning the geometric and physical parameters of the structure—such as the slit width inner and outer radii of the ring and the Fermi energy of graphene—the absorption of electromagnetic waves can be significantly enhanced over a specific frequency range. This high absorption performance is attributed to the excitation of surface plasmon resonances in graphene as well as the induced magnetic resonance modes within the ring structure. The proposed design offers high tunability and fabrication simplicity, making it a promising candidate for applications in terahertz sensing tunable absorbers and stealth technologies. https://ijpr.iut.ac.ir/article_3751.html Second harmonic generation (SHG) in solid-state lasers is always a significant aspect of nonlinear optics, achievable through certain single crystals such as potassium dihydrogen phosphate (KDP). In this study, the KDP single crystal was grown by the solution growth method using solvent evaporation at a constant temperature of 45°C, employing accurate temperature control and stabilization equipment. The grown single crystal was oriented using the X-ray Laue diffraction method, confirming its single-crystalline nature. The X-ray diffraction (XRD) analysis verified the crystalline phase formation and the absence of secondary phases in the crushed crystal sample. Fourier transform infrared (FTIR) spectroscopy confirmed the presence of bending, stretching, and other bonds. Diffuse reflectance spectroscopy (DRS) measurements yielded a bandgap of 4.12 eV for the grown crystal. The transmission spectrum demonstrated high transparency (>45%) in the 200–800 nm wavelength range. The optical axis and phase-matching angle of the grown crystal were determined based on Laue diffraction patterns, after which the crystal was rotated using a goniometer and sliced. Finally, second harmonic generation was tested using a 1064 nm Nd:YAG laser, successfully producing green light output at 532 nm. https://ijpr.iut.ac.ir/article_3752.html In this study, we employed an evolutionary algorithm and density functional theory (DFT) calculations to identify stable and metastable structural phases of aluminum-carbon compounds. Initially, a variable - composition structure search was conducted at ambient pressure to determine the convex hull of the system. Subsequently, we performed a fixed - composition structure search for alloys located on this convex hull, along with some neighboring alloys to identify their stable and metastable structural phases. Along with the most stable phase, seven metastable phases were chosen from this set, and their phonon, mechanical, and electronic properties were determined using DFT calculations. The phonon dispersion calculations reveal that all eight chosen structures are dynamically stable. A comparison of the mechanical properties of these structures reveals a novel and extremely hard phase in the aluminum-carbon alloy, which can be synthesized in thin-film form or utilized in high-temperature operating conditions. First-principles electronic structure calculations reveal that surface carbon doping in the Al-C system enables tunable metallic conductivity while maintaining an exceptional hardness-to-weight ratio. https://ijpr.iut.ac.ir/article_3727.html Graphene, a two-dimensional carbon material with properties such as high cross-sectional area and excellent electrical conductivity, has wide applications in the manufacture of volatile organic compound (VOC) sensors. These sensors allow the detection and measurement of these compounds by changing the electrical properties of graphene upon exposure to VOC molecules. Such sensors are of great importance in air quality and environmental monitoring. In this study, a monolayer graphene-silicon junction-based sensor was fabricated using photolithography and graphene wet transfer. To enhance the performance, the graphene sheet was converted into semiconducting fluorinated graphene using SF6 plasma, and then, the performance of this sensor in detecting ethanol gas was evaluated in both ohmic and transistor modes. The surface characterization of this sensor was carried out using various methods such as scanning electron microscopy and atomic force microscopy, and the effects of fluorination on graphene were also investigated through, Energy-dispersive X-ray spectroscopy, Raman spectroscopy, and attenuated total reflectance spectroscopies. Finally, the sensor performance was evaluated by measuring the current-voltage changes in the presence of ethanol gas. In terms of the mechanism of action, the adsorption of ethanol on the surface of the semiconducting fluorinated graphene leads to electron donation and an increase in the number of charge carriers. These electrical changes are the basis of the sensor performance for ethanol detection. The results show that the saturation limit is reduced by applying a gate voltage compared to the ohmic junctions, and this value becomes even lower with increasing ethanol concentration. Overall, the sensing performance in the transistor mode was better than that of the ohmic one. The development of a new generation of graphene-based VOC sensors will play a vital role in air pollution monitoring due to their high response speed, excellent sensitivity, and surface modification capabilities. https://ijpr.iut.ac.ir/article_3754.html The spin Seebeck effect is investigated in a symmetric multilayer structure consisting of two ferromagnetic insulator layers separated by a nonmagnetic insulating spacer under an applied temperature gradient. Nonlocal spin transport between the two magnetic layers is mediated by phonons excited through magnetoelastic interaction and magnetization dynamics. The results show that the generated spin current is dependent on the geometric dimensions of the structure, exhibiting an oscillatory behavior with gradual attenuation as the thickness of the non-magnetic layer increases, and a resonant behavior with respect to the thickness of the magnetic layers. Furthermore, the spin transport mediated by phonons can persist over distances ranging from several hundred micrometers to millimeters in this structure. https://ijpr.iut.ac.ir/article_3755.html In this article, the optical response of a symmetric one-dimensional photonic crystal incorporating a central defect layer of Sb₂S₃ nanomaterial in the near-infrared region is simulated and analyzed using the transfer matrix method. The effects of the amorphous-to-crystalline phase transition of the defect layer, as well as variations in the incident angle of the incoming light, on the transmission characteristics of the structure in both TE and TM polarizations are investigated. The results show that the amorphous-to-crystalline phase transition of Sb₂S₃ induces a pronounced red shift in the defect mode wavelength, whereas increasing the incidence angle leads to a blue shift of both the photonic bandgap and the defect mode in both polarizations. For TE polarization, the defect mode linewidth decreases with increasing angle, resulting in a higher quality factor; however, for TM polarization, at angles close to the Brewster angle, the defect mode merges with the bandgap edge, leading to a degradation of the filter performance. The analysis of the transmittance difference between the two phases further reveals the high angular and polarization sensitivity of the structure. These findings confirm the strong potential of Sb₂S₃ for the design of angle-sensitive optical filters and reconfigurable photonic devices with spectral switching and modulation capabilities. https://ijpr.iut.ac.ir/article_3756.html In this study, the influence of the polarization angle on the plasmonics and thermoplasmonics properties of star-shaped gold dimer nanoframes (SGDNs) with five branches is investigated using the finite-difference time-domain (FDTD) method. Notably, varying the polarization angle shifts the first localized surface plasmon resonance (LSPR) peak, while the second plasmonic mode remains unaffected. This asymmetry arises from the anisotropic geometry of the SGDNs. The simulation results show that for light polarization parallel to the dimer axis, the SGDNs can increase the local electric field up to 117 times, and the highest temperature change in the SGDNs, with a value of ΔTmax=140°C, is observed under this light polarization. Also, λ=1800 nm for the SGDNs is identified as an isosbestic point, which is independent of illumination polarization, and this characteristic can be utilized in photothermal therapy. https://ijpr.iut.ac.ir/article_3757.html In this paper, the possibility of constructing a free electron laser based on the electron beam from a Dynamitron accelerator manufactured by the Atomic Energy Organization of Iran has been studied. This study is conducted through theoretical analysis and computer simulation. The results show that if this accelerator is upgraded to deliver, at the same energy, an output current of at least 1 A, it can be used as the electron source of an oscillator-type free electron laser with an output of the order of 1 kW in the microwave region. https://ijpr.iut.ac.ir/article_3712.html Due to the significant advancements in silicon photonics, this paper presents a design of a strip silicon waveguide using COMSOL software, and its optical characteristics are simulated. The results show that this waveguide has two propagating modes, Transverse Electric (TE) mode and one Transverse Magnetic (TM) mode. The electric field profiles for these modes are illustrated at specific wavelengths. In addition, the effective refractive index, waveguide dispersion, and effective mode area have been investigated. For the proposed structure, the effective refractive index of the TM mode is always greater than that of the TE mode. Both modes have a zero dispersion wavelength over the examined wavelength range, occurring around 2.5 μm for the TM mode and approximately 2.12 μm for the TE mode. Our findings show that the effective mode area of ​​both modes is on the order of 0.1 μm2 and does not increase much with increasing wavelength. Furthermore, the effective mode area for the TE mode first increases and then decreases. Finally, by utilizing the equations governing the supercontinuum generation process in silicon waveguides, this process is studied in the proposed waveguide. The simulation results indicate that, depending on the characteristics of the injected pulse, the output from the waveguide achieves a spectral broadening of one octave. https://ijpr.iut.ac.ir/article_3759.html The nucleosome-depleted region is a part of the genome that serves as a binding site for key components of the transcriptional machinery, including RNA polymerase, transcription factors, motor proteins, and other essential cellular regulators. Occupation of this region by nucleosomes can disrupt proper transcriptional function. The sequence-dependent mechanical properties of DNA strongly influence nucleosome positioning along the genome. In this study, we present a stochastic model based on the sequence-dependent energy landscape to simulate the diffusive motion of nucleosomes along DNA. Using the Gillespie algorithm, we model the dynamics of nucleosomes along a 901-base-pair DNA segment and compute the nucleosome occupancy profile. The results show that high-energy regions act as physical barriers to nucleosome formation, leading to the emergence of NDRs. Moreover, the energy landscape of the adjacent regions plays a crucial role in the formation of NDRs and the overall distribution of nucleosomes. From the simulations, we can see a natural pattern in how nucleosomes are positioned around these NDRs. This model provides a theoretical framework for improving our understanding of chromatin organization both in vitro and in vivo. 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_3728.html One simple combination of particles which captures effect of hydrodynamics interactions consists of two trapped ‎beads, immersed in fluid, each with a single degree of freedom, and fluctuating around their equilibrium ‎positions. Given such a system in the presence of a flat boundary, we consider effect of an external electrical or ‎temperature field on it. The external field push the two beads system, out of equilibrium. We calculate beads’ ‎auto/cross correlations in the presence of external field, then investigate if these auto/cross correlations can be ‎used to reveal the presence of a possible external field, and its nature. We find that the former question could be ‎answered successfully, while the latter requires more information or degrees of freedom for beads and the ‎observer. ‎ https://ijpr.iut.ac.ir/article_3763.html In this work, the diffraction of a Gaussian beam by a radial phase grating with a sinusoidal profile is theoretically investigated. The results unambiguously confirm that this process gives rise to the formation of radial carpet beams. It is found that reducing the waist radius of the incident beam affects the intensity of the main lobe, while simultaneously confining the side-lobe intensity along the radial direction. Moreover, the wavelength of the beam incident on the radial phase grating with a sinusoidal profile plays a decisive role in shaping the diffraction pattern. The analysis further reveals that even very small variations in the number of grating sectors significantly alter the phase arrangement, although the intensity pattern remains nearly stable. The self-healing property of radial carpet beams is found to depend on both the number of grating sectors and the size of the obstructed region, such that increasing the number of sectors and decreasing the obstruction size reduces the beam’s self-healing distance. https://ijpr.iut.ac.ir/article_3764.html According to the most practical applications that use the Gaussian beam profiles from lasers in this study, Going further than applying the plane wave approximation, we consider a Gaussian coherent illumination on the two-dimensional separable structures to develop a more practical framework of the diffraction of a Gaussian beam by a radial phase grating with a binary profile that better reflects real-world experimental conditions. The results clearly demonstrate that this process leads to the formation of radial carpet beam patterns. These beams preserve their transverse structure during propagation, a property that makes their shape-invariance highly valuable for precise and controlled applications in science and technology. Furthermore, the influence of variations in the wavelength of the incident beam on the diffraction pattern of the radial phase grating with a binary is examined. The analysis reveals that the intensity distribution exhibits rotational symmetry, and that the number of lobes in the diffracted intensity and phase patterns is twice that of the corresponding radial phase grating with a binary. A comprehensive Fresnel diffraction model for a Gaussian beam interacting with radial phase gratings with a binary phase is presented, from which analytical expressions for the resulting complex optical field are derived. https://ijpr.iut.ac.ir/article_3765.html An attempt has been made to modify the original version of the Aage Winther 1995 (AW 95) potential by adding a Gaussian positive part as VRexp(-br2) to investigate the effect of the repulsive cores in the sub-barrier fusion cross sections. In order to achieve this goal, we select and evaluate 6 heavy ion fusion reactions with 392≤Z_1 Z_2≤784 (including 58Ni+54Fe, 58Ni+58Ni, 64Ni+64Ni, 16O+208Pb, 28Si+64Ni, 28Si+100Mo). The obtained results reveal that the original version of the AW potential supplemented with Gaussian positive part has been successful in reproducing the fusion excitation data for various considered systems.