arXiv subjects

Hossein Emami

Publications and source records attributed to Hossein Emami.

4 recordsLinked to original sources

arXiv2026

Monte Carlo_Based Beam Dynamics Study of a Compact Linear Accelerator for Localized X_ray Generation

Compact electron linear accelerators are being increasingly investigated as enabling platforms for localized X-ray generation and energy-controlled irradiation, due to the demand for a reduced footprint and improved beam control. In this work, a conceptual compact LINAC architecture with a fixed total length of 0.5 m is investigated through comprehensive Monte Carlo beam dynamics simulations, focusing on the comparative performance of two operating modes delivering electron beams at 60 keV and 300 keV, respectively. The study aims to isolate energy-dependent beam transport effects within an identical lattice configuration, emphasizing transverse and longitudinal phase-space evolution, emittance growth, beam envelope stability, and target spot formation. Particle tracking is performed using a statistical Monte Carlo framework incorporating RF cavity acceleration, simplified quadrupole focusing, and space-charge-induced diffusion effects. Transverse and longitudinal phase spaces are analyzed at multiple locations along the accelerator, and key beam quality metrics are extracted at the exit. The results demonstrate that low-energy operation at 60 keV is strongly influenced by collective effects, leading to pronounced emittance growth and halo formation, whereas the 300 keV mode exhibits significantly enhanced beam rigidity, improved phase space preservation, and a compact beam spot at the target.

physics.acc-ph↗

arXiv2026

Isospin-Based Supersymmetry in Neutron-Proton Pairing gap of fp-Shell Nuclei

This study presents a systematic investigation of the effects of isospin, including both T=0 and T=/0 components, on nucleon pairing correlations in fp-shell nuclei. To this aim, the interacting boson model-4, which explicitly incorporates isospin and spin degrees of freedom, is employed to examine various mass formulas associated with neutron-proton correlations in atomic nuclei. Within this framework, neutron-proton pairing gaps are derived for the first time, providing a unified description of pairing correlations in even-even, odd-A, and odd-odd systems. Furthermore, to achieve a more realistic representation of local nuclear dynamics, effective asymmetric weighting coefficients are introduced into the conventional pairing-gap expressions, motivated by physical considerations related to shell structure, blocking effects, and isospin symmetry. These coefficients are determined through a fit to experimental binding-energy data and lead to a significant improvement in the agreement between theoretical predictions and observed systematic. Additionally, the results support the central assumption regarding the supersymmetry of the first fp-shell nuclei, highlighting the essential role of isospin-dependent effects in shaping neutron-proton pairing collectivity.

nucl-th↗

arXiv2025

Variations of two-neutron separation energies and thermal-neutron capture cross sections versus the pairing gap

In this work, we investigate the experimental correlation between the pairing gap values and two important observables in the study of nuclear structure (two neutron separation energies and thermal-neutron capture cross-sections). To this aim, we focused on the even-even nuclei in the vicinity of Z=50 and Z = 82 closed proton shells, for which the quantum phase transition phenomena are reported. The results show a significant correlation between the pairing gap and the well-known signatures of quantum phase transitions in the nuclei, which are the candidates for E(5) and X(5) critical points. Also, we have explained the special relation between the pairing gap and the cross-section of thermal neutrons in the considered isotopic chains.

nucl-th↗

arXiv2025

Pairing gap as a new observable for critical points in the region of A=100

This study used the pairing gap to identify nuclei as candidates for critical point symmetry around Z=40 and A=100. Nuclei around A = 100 display complex shape evolution and configuration crossing patterns. We utilized the experimental and algebraic frameworks of the interacting boson model and the newly developed interacting boson-fermion model to study the isotopes of Mo and Ru. The results show significant variations in these quantities across nuclei located at the E(5) and X(5) critical points, analyzed through different observables. We also examined another region that is suitable for a shape phase transition. Furthermore, our findings suggest new candidates for critical points in other phase transitional regions for different isotopic chains.

nucl-th↗