Angular Distribution Of Particles Research Articles

Investigation of reaction and α production cross sections with 9Be projectile

In order to investigate the contribution of α production in the reaction cross sections, measurements of elastic scattering and inclusive α particle angular distributions have been carried out with the 9Be projectile on 89Y, 124Sn, 159Tb, 198Pt, and 209Bi targets over a wide angular range at energies near the Coulomb barrier. The measured elastic scattering angular distributions were fitted with optical model calculations, and reaction cross sections were extracted. The same data were also analyzed using both global optical model potentials (Global OMP) and microscopic São Paulo potentials (SPP), to obtain the reaction cross sections. The data available in the literature for 9Be projectile includes the elastic scattering angular distributions, α production cross sections, and complete fusion cross sections on these and other targets at several energies are also utilized for comparative studies. The reaction cross section extracted from the three potentials (Best Fit, Global OMP and SPP) are in reasonable agreement for all the targets except for the energies below the barrier where the results from SPP deviate by 30-50%. Inclusive α particle production cross sections were also extracted by integrating the α particle angular distributions. The present data and data available from literature of reaction and α-particle production cross sections were utilized to make systematic studies. Systematics of reaction and α-particle production cross sections revealed their universal behavior. The ratio of complete fusion (CF), inclusive α cross sections, and their sum (CF+α) to reaction cross sections show that at sub-barrier energies inclusive α dominates and above barrier CF dominates, and cumulative of these two processes almost explains the reaction cross section at all energies over a wide range of target mass. A comparative study of α production with other weakly bound projectiles is also performed and a clear distinction between projectile types is observed, which is found to correlate well with α separation energies of the projectiles.

Extended characterization of alpha particles via laser-induced p-11B fusion reaction in silicon hydrogenated boron-doped thin targets

The nuclear fusion channel of the p-11B reaction producing α particles with multi-MeV kinetic energies was induced by a sub-nanosecond laser pulse focused onto 10 μm thick boron-doped thin targets at intensities of ∼ 1016 W/cm2. A full characterization in terms of α particle flux and angular distribution was performed thanks to the simultaneous use of several diagnostics (time-of-flight detectors, nuclear track detectors, and Thomson Parabola spectrometers), which enabled to measure key features of particles produced both in the backward (target front side) and forward (target rear side) directions. Maximum α particle flux and cut-off energy were recorded at small detection angles with respect to the target normal in the backward direction. The maximum kinetic energy shown by the α-particles produced in the nuclear fusion reaction was ascribable to a post-accelerating transient electric field present in the laser-generated plasma, in agreement with our previous preliminary results.

Enrichment of Scavenged Particles in Jet Drops Determined by Bubble Size and Particle Position

When small bubbles rupture in a contaminated water source, the resulting liquid jet breaks up into droplets that can aerosolize solid particulates such as bacteria, viruses, and microplastics. Particles collected on the bubble surface have the potential to become highly concentrated in the jet drops, dramatically increasing their impact. It has been assumed that only particles small enough to fit within a thin microlayer surrounding the bubble can be transported into its influential top jet drop. Yet here, we demonstrate that not only can larger particles be transported into this jet drop, but also that these particles can exceed previous enrichment measurements. Through experiments and simulations, we identify the prerupture location of the liquid that develops into the top jet drop and model how interfacial rearrangement combines with the bubble size, particle size, and the angular distribution of particles on the bubble surface to set the particle enrichment.

Photoproduction of e+e− pair in a Coulomb field near the threshold

We consider the electron-positron pair production by a photon in Coulomb field near threshold. We obtain the analytical results for the particle energy spectrum and angular distribution exactly in the parameter Ze2/ħv. We show that Furry-Sommerfeld-Maue approximation for the wave functions used by Nishina, Tomonaga and Sakata in Ref. [1] is not sufficient and leads to wrong results.

Optimization of molecular beam epitaxial film thickness uniformity using Monte Carlo simulations and an artificial neural network.

The thickness uniformity of the molecular beam epitaxial film is one of the most important factors affecting the quality of the film, and it is mainly influenced by the angular distribution of the molecular source, which is mainly determined by the inner wall shape of the crucible. In this paper, an optimization method based on particle swarm optimization, Monte Carlo simulations, and an artificial neural network is proposed, aiming at optimizing the epitaxial film uniformity in the molecular beam epitaxy process. The optimum angular distribution of an effusion source is obtained by using the method of particle swarm optimization for a given geometric configuration. The Monte Carlo method is used to simulate the particle evaporation process to obtain the relationship between the shape parameters of the crucible inner wall and the particle angular distribution. The optimum crucible shape parameters are subsequently obtained under a particular apparatus geometric configuration by using the artificial neural network according to the above relationship and the desired optimum angular distribution. Finally, the optimized results are compared by experiments.

Angular distribution of particles sputtered from the vanadium target by 5 keV Kr ions: simulation study

The sputtering of vanadium particles at normal incidence was simulated. The SRIM-code combined to a new ANGULAIR and SDTrimSP simulation was employed to obtain the sputtering yields and the angular distribution of the atoms. The simulation was made for a large number of incident Kr+ ions with 5 keV energy, letting the computer count the number of emitted particles in the solid angle. The angular distribution of differential sputtering yields of vanadium shows an over-cosine tendency.

Conceptual design report of the MPD Cosmic Ray Detector (MCORD)

This report presents a concept of constructing a detector dedicated for detection of muons observed during measurements carried out at the MPD (Multi-Purpose Detector) detector that is currently under construction at the NICA facility, Russia, Dubna. It has been proposed to design and build an additional detector that will complement the current MPD set and increase its measurement capabilities. The main goal of this project is to provide information from cosmic muons that pass the MPD detector in both in-beam and off-beam experiments. Hence, the detector is called the MPD COsmic Ray Detector (MCORD).The conceptual design of MCORD is proposed by a Polish consortium NICA-PL comprising several Polish scientific institutions.The data from cosmic ray muons could be used as a trigger for calibration of other detection systems comprising the MPD detector. Large surface covered by the MCORD offers also possibility for efficient registration of muons generated in expanding atmospheric showers induced by distant sources. Moreover, beyond some energy threshold, observation of muons originating from decays of collision products will also be possible. In this report examples of the MCORD functionality as a part of the MPD detector are presented.The MCORD is designed as a universal, fast triggering system built as a modular reconfigurable construction. The detection system will be based on plastic scintillators equipped with wavelength shifting fibers, and silicon photomultipliers (SiPM) will be used for scintillation readout. The online analysis of received signals will be performed using digital FPGA modules. Due to the modular design, the same system (its small part) can be used for both laboratory testing of other MPD sub-detectors, and the calibration of these detectors after placing them inside the MPD in off-beam mode. The full detector will support these systems as an additional trigger, calibrator, and muon identifier during the normal operation of the MPD detector with the beam. Thanks to its unique construction, it will expand the possibilities of collecting scientific data of the MPD detector with astrophysical observations.The publication will show the assumptions of the mechanical structure and electronic systems of the planned detector. The installation site of the detector as part of the MPD detector will be described in detail. In the following, the results of simulations made in preparation for this project will be presented. In particular, simulations with the CORSIKA code present angular distributions of particles in cosmic showers in the Dubna city region. Since muons dominate the cosmic ray showers, the MPD detector response to expected cosmic muon flux was also simulated. The results provide information about the muon cut-off thresholds depending on the MPD detector composition during the installation campaign. Simulations of muon events that could be used for MPD subsystems calibration were also performed. The results shown for various configuration of MCORD detector modules will enable the estimation of the time necessary to perform such tests in the future.Simulations with UrQMD model shows the muon abundances due to beam-beam collisions. Approximately 90% of muons are created from pions, whereas the number of muons that reach the MCORD detector is 10 times greater than the number of pions. The MPD detector response was also simulated under the influence of a stream of various particles, especially muons. It shows energy dependence of muon transmission coefficient for MPD with and without ECal assembled. Assuming requirement for muon transmission above 95%, the muon cut-off thresholds are 1.6 GeV and 2.0 GeV, respectively.MCORD detector performance evaluation is also reported. In the case when we used scintillators with one fiber with a diameter of 1 mm, the time resolution of about 1.0 ns was recorded, which corresponds to the positional accuracy (σx) of 7.1 cm. The results of laboratory tests show that application of a 2 mm diameter WLS fiber instead of the previously used 1 mm diameter fiber improves the time resolution to 0.80 ns.

Angular distribution of particles sputtered from a copper target by 5‐keV Kr ions: Experiment and simulation study

Angular distributions of atoms sputtered from a copper target under 5‐keV Kr+ bombardment at normal incidence were simultaneously and independently studied by experiments and computer simulation. The sputtered particles are collected on a Mylar™ foil placed around the target. Deposited particles on the substrate were analyzed by optical transmission spectroscopy. The surface roughness of the irradiated target was studied by atomic force microscopy, surface profilometry, and scanning electron microscopy. The experimental results were compared with the simulated angular distributions (programs OKSANA, SDTrimSP, and SRIM) and were found to be in reasonable agreement. In all cases, the angular distribution of sputtered particles showed an over‐cosine shape, which may be associated with noncompensated scattering of ejected particles by surface atoms when exiting the target. The results obtained are compared with the data from the literature.

The Self-Absorption Effect of Ni-63 Beta Source to the Silicon Carbide based Betavoltaic Battery

A typical planar structure is the most feasible conceptual design of betavoltaic battery due to its simplicity. The self-absorption of beta source, however, causes a limitation to the geometrical efficiency. Herein, we tried to investigate the self-absorption event in Ni-63 beta source by changing the geometrical aspects and evaluated its effect on each layer of a 4H-SiC semiconductor as the radiation-electricity converter. The design configuration from previous literature was adopted and the model was developed using Monte Carlo N-Particle X (MCNPX) consists of radioisotope source, semiconductor, and also ohmic contacts. The energy of beta emission was adjusted to the actual Ni-63 beta spectra with an isotropic distribution of ejected particles. The average beta energy deposition degrades along with the addition of source mass thickness, but the n+ substrate has a unique result where a peak is observed at 0.1246 mg/cm2 due to the self-absorption effect. Furthermore, the rectangular surface area magnification gives a positive impact on the beta energy deposition up to 2.48% and the photon average energy deposition up to 137.21%. The results of average electron absorbed dose are consistent with Oldano-Pasquarelli semi-empirical theory of self-absorption in the beta source, where the upper layer receives a wider angular distribution of particles compared to the lower one, which corresponds to the counting geometrical coefficients.

About electrons and position in triplet production: Some remarks

Taking into account the increasing interest in measuring high energy gamma ray polarization, Boldishev et. at ( 1994) [1]. published an extensive and very comprehensive work on the possibility of using the recoil electrons in the production of pairs on electrons. However, this work is based on using only 2 Feynmann diagrams of the 8 that the process has. This eliminates the difficulty of distinguishing, in the theory, which is the recoil electron and which is the created.In this work we have analyzed the eight Feynman diagrams and we have shown that for energies lower to ~1000mc2, the assumption just described is not a good approximation, so we propose a different way to work (Iparraguirre, 2014) [2]: we classify the electrons into the less energetic and the most energetic ones without taking into account their origin. Under these conditions (lower or higher energy value), we have calculated the contribution of the different diagrams to the distribution (we compare the sum of them with that obtained by Haug (1975; 1985) [3,4], and how these distributions are modified by introducing a threshold for the momentum detection for electrons.For the study of polarization we presented on the angular distribution of particles for high-energy gamma rays (where only Borsellino diagrams predominate). Our results on the azimuthal distribution show that it is highly influenced by the orientation (in the plane perpendicular to the direction of the photon), prior to the interaction, that the polarization vector has with respect to the position of the electron in whose field the pair will be generated.

Aligned CP-violating Higgs sector canceling the electric dipole moment

We discuss the effect of CP violation in the aligned scenario of the general two-Higgs-doublet model, in which the Higgs potential and the Yukawa interaction provide additional CP-violating phases. An alignment is imposed to the Yukawa interaction in order to avoid dangerous flavor changing neutral currents. The Higgs potential is also aligned such that the coupling constants of the lightest Higgs boson, which is identified as the discovered Higgs boson with the mass of 125 GeV, are the same as those of the standard model. In general, CP-violating phases originated by the Yukawa interaction and the Higgs potential are strongly constrained by the current data for the electric dipole moment (EDM). It is found that in our scenario contributions from the two sources of CP violation can be destructive and consequently their total contribution can satisfy the EDM results, even when each CP-violating phase is large. Such a large CP-violating phase can be tested at collider experiments by looking at the angular distributions of particles generated by the decays of the additional Higgs bosons.

The Distribution Function of Solar Cosmic Rays under Prolonged Particle Injection

Abstract—The propagation of solar cosmic rays (SCR) in the interplanetary medium is considered on the basis of the Fokker–Planck kinetic equation. It is known that the SCR distribution function averaged over a solar proton event contains valuable data on the scattering process for energetic charged particles by interplanetary magnetic fields. A steady-state solution for the kinetic equation in the small-angle approximation is obtained, and the dependence of the angular distribution function of cosmic rays on the distance to the particle source is examined. This solution is applicable if the distance to the particle source is short compared to the mean free path of cosmic rays and if particles are moving primarily in the radial direction. The angular distribution of particles at large (compared to the mean free path of cosmic rays) distances to the particle source is also analyzed. An analytical expression for the distribution function of cosmic rays in the form of a sum of an isotropic component and a small anisotropic one is derived. It is demonstrated that the angular distribution of cosmic rays depends to a considerable extent on the anisotropy of their scattering. The scattering characteristics of energetic charged particles by fluctuations of interplanetary magnetic fields are estimated based on observational data for several SCR flares.

Surface roughness effect on Mo physical sputtering and re-deposition in the linear plasma device PSI-2 predicted by ERO2.0

Abstract Surface morphology and its evolution during the plasma irradiation is known to have a large influence on the erosion and resulting lifetime of plasma-facing components as well as tritium retention. For instance, surface roughness can affect physical sputtering, re-deposition, as well as angular distributions of the sputtered species. In this study the effect of surface roughness is implemented into the 3D Monte-Carlo code ERO2.0. First modelling results for molybdenum (Mo) irradiated with deuterium (D) in the conditions foreseen for the planned experiments at the linear plasma device PSI-2 are presented. Using the constructed examples of surfaces with various (regular and fractal) roughness types it is shown that the effective sputtering yield decreases for rough surfaces in comparison to smooth ones. The angular distribution of particles escaping from the rough surface collimates with the increase of the surface structure's aspect ratio. Moreover, the modelling predicts flattening of the surface during the plasma irradiation due to the preferable re-deposition in the “valleys” and sputtering of the peak tops.

Correlation study in high energy interaction of muon with Ag and Br nuclei

In this work, we present the study of emissions of light fragments produced in interactions of 160 GeV muons with emulsion nuclei. A total of 820 interactions with emulsion nuclei were collected. Thickness, coordinate and range of each track were measured. Charges of emitted fragments were identified and the corresponding energies were calculated. Multiplicity, total particle production cross-sections and angular distribution of particles (P, He, Li, Be and B) were presented. Forward–backward–angular correlations were measured for the emitted alpha particles. Short and long range correlation among pairs of Alfa particles were observed at specific angular intervals. The experimental data and the results of the angular correlation were used to find the probable mechanism of producing alpha particles and to reveal the dynamic characteristics of the reactions.

Description of Solar Cosmic Ray Propagation in the Interplanetary Medium on the Basis of the Kinetic Equation

The propagation of solar cosmic rays in interplanetary space is considered based on the kinetic equation. The expression for cosmic ray density under instantaneous particle injection by a point-like source is obtained. The set of a differential equation system for harmonics of cosmic ray distribution function is obtained starting from the kinetic equation. The cosmic ray transport equation, taking into account the presence of the second harmonic of particle angular distribution, is derived and the solution of this equation is obtained.

Study of TiC particle distribution in Al-MMCs using finite element modeling

In order to enhance the efficiency of cutting process before resorting to costly and time consuming experimental trials, it is necessary to model and simulate the machining process by using Finite Element (FE) analysis. However, modeling of composite machining is difficult owing to its distinctive structure and composition which is anisotropic and heterogeneous. Limited studies have been done using microscopic model without considering the effect of particle distribution on chip morphology and coupled temperature displacement analysis during machining simulation of MMCs. Therefore, in the current research work an FE model of machining MMCs is built for analyzing the effect of particle distribution in matrix, tool and geometry cutting parameters on machining process. In FE analysis, the main phases of an Al-TiC MMC workpiece, namely the particle phase and the matrix phase are modeled. Parameters such as morphology of chip, cutting force, and temperature and stress distribution have significant influence on cutting performance and are successfully analyzed by 2D FE models developed. Two different strategies (model A and B) are utilized to arrange the particles in the matrix. Model B with angular distribution of particles shows better performance than the linear distribution of particles in model A. The Performance of model B at different machining conditions is successfully performed and achieves closer to experimental results. Further, heat transfer properties are incorporated in the FE code to perform the cryogenic machining simulation. The authenticity of the developed model is ensured as the simulation results closely agree with the experimental results. The developed FE model affords an insight on effect of particle distribution, cutting parameters and cryogenic technology on machining of MMC. The details presented in the current work are likely to form a scientific basis to simulate machining of MMCs to address the present-day requirements of manufacturing industries.

Description of Differential Cross Sections for 63Cu + p Nuclear Reactions Induced by High-Energy Cosmic-Ray Protons

The results of calculation of 63Cu + p differential cross sections at incident-proton energies between 10 and 200 MeV and a comparative analysis of these results are presented as a continuation of the earlier work of our group on developing methods for calculating the contribution of nuclear reactions to radiative effects arising in the onboard spacecraft electronics under the action of high-energy cosmic-ray protons on 63Cu nuclei (generation of single-event upsets) and as a supplement to the earlier calculations performed on the basis of the TАLYS code in order to determine elastic- and inelastic-scattering cross sections and charge, mass, and energy distributions of recoil nuclei (heavy products of the 63Cu + p nuclear reaction). The influence of various mechanisms of the angular distributions of particles emitted in the 63Cu + p nuclear reaction is also discussed.

Spectral characterization of laser-accelerated protons with CR-39 nuclear track detector.

CR-39 nuclear track material is frequently used for the detection of protons accelerated in laser-plasma interactions. The measurement of track densities allows for determination of particle angular distributions, and information on the kinetic energy can be obtained by the use of passive absorbers. We present a precise method of measuring spectral distributions of laser-accelerated protons in a single etching and analysis process. We make use of a one-to-one relation between proton energy and track size and present a precise calibration based on monoenergetic particle beams. While this relation is limited to proton energies below 1 MeV, we show that the range of spectral measurements can be significantly extended by simultaneous use of absorbers of suitable thicknesses. Examples from laser-plasma interactions are presented, and quantitative results on proton energies and particle numbers are compared to those obtained from a time-of-flight detector. The spectrum end points of continuous energy distributions have been determined with both detector types and coincide within 50-100 keV.

Propagation of galactic cosmic rays in the outer heliosphere

The propagation of galactic cosmic rays in heliospheric magnetic fields is studied. An approximate solution to the cosmic ray transport equation has been derived on the basis of a method that takes into account the small value of anisotropy of particle angular distribution. The spatial and energy distributions of the cosmic ray intensity and anisotropy have been investigated, and estimates of cosmic ray energy flux have been carried out.

Comparison of experiments and computations for cold gas spraying through a mask. Part 2

This paper presents experimental and simulation results of cold spray coating deposition using the mask placed above the plane substrate at different distances. Velocities of aluminum (mean size ~ 30 μm) and copper (mean size ~ 60 μm) particles in the vicinity of the mask are determined. It was found that particle velocities have angular distribution in flow with a representative standard deviation of 1.5–2 degrees. Modeling of coating formation behind the mask with account for this distribution was developed. The results of model agree with experimental data confirming the importance of particle angular distribution for coating deposition process in the masked area.