scholarly journals Reliability and Comparison of Some GEANT4-DNA Processes and Models for Proton Transportation: An Ultra-Thin Layer Study

2021 ◽  
Author(s):  
Gabriela Hoff ◽  
Raquel S. Thomaz ◽  
Leandro I. Gutierres ◽  
Sven Muller ◽  
Viviana Fanti ◽  
...  
Keyword(s):  
Cross Sections ◽  
Radiation Transport ◽  
Thin Layers ◽  
Depth Profiles ◽  
Chemical Damage ◽  
Diffusion Parameters ◽  
Experiment Versus ◽  
Deposited Energy ◽  
Simulation Results ◽  
Dynamic Diffusion

This chapter presents a specific reliability study of some GEANT4-DNA (version 10.02.p01) processes and models for proton transportation considering ultra-thin layers (UTL). The Monte Carlo radiation transport validation is fundamental to guarantee the simulation results accuracy. However, sometimes this is impossible due to the lack of experimental data and, it is then that the reliability evaluation takes an important role. Geant4-DNA runs in an energy range that makes impossible, nowadays, to perform a proper microscopic validation (cross-sections and dynamic diffusion parameters) and allows very limited macroscopic reliability. The chemical damage cross-sections reliability (experiment versus simulation) is a way to verify the consistency of the simulation results which is presented for 2 MeV incident protons beam on PMMA and PVC UTL. A comparison among different Geant4-DNA physics lists for incident protons beams from 2 to 20 MeV, interacting with homogeneous water UTL (2 to 200 nm) was performed. This comparison was evaluated for standard and five other optional physics lists considering radial and depth profiles of deposited energy as well as number of interactions and stopping power of the incident particle.

Photonuclear Physics in Radiation Transport—III: Actinide Cross Sections and Spectra

2006 ◽  
Vol 153 (1) ◽  
pp. 33-40 ◽  
Author(s):  
M.-L. Giacri-Mauborgne ◽  
D. Ridikas ◽  
M. B. Chadwick ◽  
P. G. Young ◽  
W. B. Wilson
Keyword(s):  
Cross Sections ◽  
Radiation Transport ◽  
Photonuclear Physics

Untersuchungen zur Wirkung von monochromatischer Vakuum-UV-Strahlung auf DNS

1969 ◽  
Vol 24 (6) ◽  
pp. 722-728 ◽  
Author(s):  
K. U. Berger
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Electron Emission ◽  
Vacuum Ultraviolet ◽  
Monochromatic Light ◽  
Ionization Probability ◽  
Thin Layers ◽  
Inactivation Mechanism ◽  
Grating Monochromator ◽  
Vacuum Uv

Inactivation cross sections of infectious ΦΧ-174-DNA in the extreme vacuum-ultraviolet were determined by irradiation of thin layers with monochromatic light down to 584 Å by means of a powerful grating-monochromator, the elements of which are described. Comparison of inactivation and light-induced electron emission shows that light of quantum energies below 7 eV inactivates by excitation only, whereas above 10.2 eV ionization is the predominant inactivation mechanism. Because of the satisfactory agreement of the curves for inactivation and electron emission, it is conducted that the remarkable increase of the inactivation cross section in the region of the short wavelength vacuum-uv is due to increasing ionization probability.

Modeling Energy Deposition in Very Thin Layered Media by Monte Carlo Simulation

2007 ◽  
Author(s):  
Reginald Eze ◽  
Anisur Rahman ◽  
Sunil Kumar
Keyword(s):  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Thin Layer ◽  
Layer Thickness ◽  
Path Length ◽  
Energy Deposition ◽  
Radiation Transport ◽  
Monte Carlo Model ◽  
Layered Media ◽  
Thin Layers

A Monte Carlo model with special features for modeling of radiation transport through very thin layers has been presented. Over the decades traditional Monte Carlo model has been used to model highly scattering thin layers in skin and may inaccurately capture the effect of thin layers since their interfaces are not perfectly planar and thicknesses non-uniform. If the Monte Carlo model is implemented without special features then the results of the simulation would show no effect of the outer thin layer since the path length of most photons would be significantly larger than the layer thickness and the resulting predicted photon travel would simply not notice the presence of the layer. Examples of multi-layered media are considered where the effect of a very thin absorbing layers is systematically examined using both the traditional Monte Carlo and that with new features incorporated. The results have profound implications in the diagnostic and therapeutic applications of laser in biomedicine and surgery.

Zur biologischen Wirksamkeit elastischer Kernstöße

1965 ◽  
Vol 20 (8) ◽  
pp. 764-772 ◽  
Author(s):  
H. Jung
Keyword(s):  
Energy Loss ◽  
Enzymatic Activity ◽  
Cross Section ◽  
Cross Sections ◽  
Proton Energy ◽  
Nuclear Collision ◽  
Thin Layers ◽  
Elastic Collisions ◽  
Nuclear Collisions ◽  
Sharp Minimum

Extremely thin layers of ribonuclease were irradiated with slow protons and the differential inactivation cross section determined for various proton energies in the range from 0.8 to 60 keV. At higher proton energies the inactivation cross section is not strongly dependent on energy but with decreasing proton energy it decreases rapidly, reaches a sharp minimum at 1.2 keV and increases again at still smaller energies. By comparing the experimentally determined inactivation cross sections with the cross sections for energy loss in elastic nuclear collisions and in ionizations, respectively, elastic collisions were demonstrated to destroy, in fact, the enzymatic activity of ribonuclease. The energy required for an inactivation by nuclear collision is only one fourth of the energy necessary for an inactivation by ionization.

Time Series Analysis in Pooled Cross-Sections

1986 ◽  
Vol 2 (3) ◽  
pp. 331-349 ◽  
Author(s):  
John J. Beggs
Keyword(s):  
Time Series ◽  
Time Series Analysis ◽  
Cross Sections ◽  
Spectral Methods ◽  
Time Series Data ◽  
Series Data ◽  
Cross Sectional ◽  
Series Analysis ◽  
Simulation Results ◽  
Spectral Representations

This article proposes the use of spectral methods to pool cross-sectional replications (N) of time series data (T) for time series analysis. Spectral representations readily suggest a weighting scheme to pool the data. The asymptotically desirable properties of the resulting estimators seem to translate satisfactorily into samples as small as T = 25 with N = 5. Simulation results, Monte Carlo results, and an empirical example help confirm this finding. The article concludes that there are many empirical situations where spectral methods canbe used where they were previously eschewed.

High accuracy radiative data for plasma opacities1This article is part of a Special Issue on the 10th International Colloquium on Atomic Spectra and Oscillator Strengths for Astrophysical and Laboratory Plasmas.

2011 ◽  
Vol 89 (4) ◽  
pp. 439-449 ◽  
Author(s):  
Sultana N. Nahar
Keyword(s):  
Cross Sections ◽  
Radiation Transport ◽  
High Energy ◽  
Oscillator Strengths ◽  
International Colloquium ◽  
Radiative Processes ◽  
Elemental Abundances ◽  
Ionization Cross Sections ◽  
Photo Ionization ◽  
Atomic Parameters

Opacity, which gives the measure of the radiation transport in plasmas, is caused by the repeated absorption and emission of the propagating radiation by the constituent plasma elements. Microscopically, opacity (κ) depends mainly on two radiative processes: (i) photo-excitation (bound-bound transition) and (ii) photo-ionization (bound-free transition) in addition to electron-photon scattering. The monochromatic opacity κ(ν) at photon frequency ν is determined by the atomic parameters, oscillator strengths (f), and photo-ionization cross sections (σPI). However, total monochromatic opacity is obtained from summed contributions of all possible transitions from all ionization stages of all elements in the source. The calculation of accurate parameters for such a large number of transitions has been the main problem for obtaining accurate opacities. The overall mean opacity, such as the Rosseland mean opacity (κR), depends also on the physical conditions, such as temperature, density, elemental abundances, and equation of state. The necessity for high-precision calculations for opacities may be exemplified by the existing problems, such as the determination of solar elemental abundances. With new computational developments under the Iron Project, we are able to calculate more accurate atomic parameters, such as oscillator strengths for large number of transitions using the relativistic Breit–Pauli R-matrix (BPRM) method. We are finding new features in photo-ionization, such as the existence of extensive and dominant resonant structures in the high-energy region not studied before. These new data should provide more accurate opacities in high-temperature plasmas and can be used to investigate the well-known solar abundance problem.

scholarly journals Optimization of the Turbulence Model on Numerical Simulations of Flow Field within a Hydrocyclone

2015 ◽  
Vol 2015 ◽  
pp. 1-7
Author(s):  
Yan Xu ◽  
Zunce Wang ◽  
Lin Ke ◽  
Sen Li ◽  
Jinglong Zhang
Keyword(s):  
Flow Field ◽  
Large Eddy Simulation ◽  
Cross Sections ◽  
Three Dimensional ◽  
Reynolds Stress Model ◽  
Computational Grids ◽  
Test Results ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Simulation Results

Reynolds Stress Model and Large Eddy Simulation are used to respectively perform numerical simulation for the flow field of a hydrocyclone. The three-dimensional hexahedral computational grids were generated. Turbulence intensity, vorticity, and the velocity distribution of different cross sections were gained. The velocity simulation results were compared with the LDV test results, and the results indicated that Large Eddy Simulation was more close to LDV experimental data. Large Eddy Simulation was a relatively appropriate method for simulation of flow field within a hydrocyclone.

scholarly journals Influence of the volute cross-sectional shape on mixed inflow turbine performances

2017 ◽  
Vol 9 (7) ◽  
pp. 168781401770817 ◽  
Author(s):  
Mohamed Amine Meghnine ◽  
Mohammad Kamal Hamidou ◽  
Mohammed Hamel
Keyword(s):  
Cross Sections ◽  
Radial Direction ◽  
Essential Element ◽  
Sectional Area ◽  
Cross Sectional ◽  
Flow Angle ◽  
Absolute Flow ◽  
Subsonic Regime ◽  
Simulation Results ◽  
Sectional Shape

The volute is an essential element in the centrifugal machines. Improving its performance is an effective way to improve the total performance of the turbine. The purpose of this study is to replace the accelerating and guiding nozzle vanes by exploring different design possibilities on the cross-sectional area convergence of the volute, since a decreasing area is then associated with expansion in the subsonic regime. The work is extended to a mixed inflow turbine using the new volute cross sections under pulsating regimes for turbocharging. The numerical simulation results show larger accelerations [Formula: see text] and lesser losses in the case of sections with flatter area in the radial direction and without vaneless space between the volute and the rotor; but this combination has an effect on the exit absolute flow angle which is less uniform.

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