arXiv subjects

Jesus Rubayo-Soneira

Publications and source records attributed to Jesus Rubayo-Soneira.

4 recordsLinked to original sources

arXiv2026

The impact of experimental conditions on the observation of channeling and crystalline undulator radiation

In this study, we present a comprehensive quantitative analysis of the radiation emitted by 855 MeV electrons propagating through an oriented diamond hetero-crystal. The crystal consists of two distinct segments: (i) a straight single-crystal diamond substrate, and (ii) a diamond layer that is periodically doped with boron atoms. The doping profiles were derived from precise experimental measurements of boron concentration obtained during the layer fabrication via Microwave Plasma Chemical Vapor Deposition (MPCVD). Our study systematically investigates the channelling and the crystalline undulator radiation, accounting for the different doping profiles in the undulating region. The simulations were conducted using the advanced MBNExplorer software package, which enables detailed modeling of particle trajectories and radiation emission. We report on good agreement with experiment and discuss remaining discrepancies providing possible explanations for them. The results obtained show that the radiation intensity is significantly affected by a range of factors, including the angular divergence of the incident beam, its orientation with respect to the target, the direction in which the emitted radiation is detected, and the choice of the doping profiles. These findings are important for optimising the design of crystalline undulators as novel gamma radiation light sources.

physics.acc-ph↗

arXiv2023

Multiple scattering of 855 MeV electrons in amorphous and crystalline silicon: simulations versus experiment

The angular distribution function of multiple scattering experienced by 855 MeV electrons passing through an amorphous silicon plate and an oriented silicon crystal has been studied by means of relativistic molecular dynamics simulations using two types of the potentials that describe electron-atom interaction. The differences in the angular distributions of the beam particles in both media are analysed. The results obtained are compared to the experimental data and to the results of Monte Carlo simulations.

physics.comp-ph↗

arXiv2020

Two-Photon Excited Fluorescence Dynamics in NADH in water-methanol solutions: the Role of Conformational States

The dynamics of polarized fluorescence in NADH at 460 nm under two-photon excitation at 720 nm by femtosecond laser pulses in water-methanol solutions has been studied experimentally and theoretically as a function of methanol concentration. A number of fluorescence parameters have been determined from experiment by means of the global fit procedure and then compared with the results reported by other authors. A comprehensive analysis of experimental errors was made. The interpretation of the experimental results obtained was supported by ab initio calculations of the structure of NADH and NMNH in various solutions. An explanation of the heterogeneity in the measured decay times in NADH and NMNH has been suggested based on the influence of the internal molecular electric field in the nicotinamide ring on non-radiative decay rates. We suggest that different charge distributions in the cis and trans configurations result in different internal electrostatic field distributions that lead to the decay time heterogeneity. A slight but noticeable rise of the decay times tau_1 and τ_2 with methanol concentration was observed and treated as a minor effect of a non-radiative relaxation slowing due to the decrease of solution polarity. The analysis of the rotational diffusion time tau_r as a function of methanol concentration on the basis of the Stokes-Einstein-Debye equation allowed for determination of relative concentrations of the folded and unfolded NADH conformations in solutions. The analysis of the fluorescence anisotropy parameters and parameter Omega determined from experiment allowed for determination of the two-photon excitation tensor components and suggested the existence of two excitation channels with comparable intensities.

physics.chem-ph↗

arXiv2003

Hadron spectra from a non-relativistic model with confining harmonic potential

Hadron spectra and other properties of quark systems are studied in the framework of a non-relativistic spin-independent phenomenological model. The chosen confining potential is harmonic, which allowed us to obtain analytical solutions for both meson and baryon (of equal constituent quarks) spectra. The introduced parameters are fixed from the low-lying levels of heavy quark mesons. The requirement of flavor independence is imposed, and it restricts the possible choices of inter-quark potentials. The hyper-spherical coordinates are considered for the solution of the three-body problem.

physics.ed-ph↗