Experimental evidence for the existence of a Ramsauer–Townsend minimum in liquid CH4 and Ar (Kr and Xe) and in gaseous C2H6 and C3H8

1977 ◽  
Vol 55 (11) ◽  
pp. 1876-1884 ◽  
Author(s):  
L. G. Christophorou ◽  
D. L. McCorkle
Keyword(s):  
Experimental Evidence ◽  
Cross Section ◽  
Electron Scattering ◽  
Cross Sections ◽  
Electron Mobility ◽  
Scattering Cross Section ◽  
Thermal Electron ◽  
Scattering Cross ◽  
Dilute Gas ◽  
Scattering Cross Sections

Experimental evidence for the existence of a Ramsauer–Townsend minimum in the electron scattering cross section for liquid CH4 and liquid Ar (Kr and Xe) is presented and discussed. On the basis of evidence obtained from three sources: (i) comparisons of thermal electron mobilities in gases with those in liquids, (ii) changes in the electron mobility with gas density at high and very high gas pressures, and (iii) the dependence of the electron mobility on temperature for liquids whose V0, the energy of the electron state in the liquid, is ≤0 eV, it is concluded that a Ramsauer–Townsend minimum is exhibited by the electron scattering cross section for CH4, Ar (Kr and Xe) at all densities from a dilute gas to the liquid and that this minimum is shifted to lower energies (closer to thermal) with increasing density.Additionally, it has been found that a Ramsauer–Townsend-type behavior is exhibited by gaseous ethane (C2H6) and propane (C3H8) with the cross section minimum located at lower energies than for methane (CH4). For these latter molecules the measured mean scattering cross sections at thermal energies are comparable with the geometric cross sections.

Electron scattering cross sections of gaseous pentanes and hexanes

1979 ◽  
Vol 57 (19) ◽  
pp. 2626-2628 ◽  
Author(s):  
Gordon R. Freeman ◽  
István György ◽  
Sam S.-S. Huang
Keyword(s):  
Electron Energy ◽  
Cross Section ◽  
Electron Scattering ◽  
Cross Sections ◽  
Scattering Cross Section ◽  
Low Energy ◽  
Electron Velocity ◽  
Scattering Cross ◽  
Scattering Cross Sections ◽  
Energy Side

Electron scattering cross sections σv have been estimated as functions of electron velocity v for six gaseous pentanes and hexanes. The scattering cross section of each compound has a minimum in the vicinity of υ = (2–3) 107 cm/s, corresponding to an electron energy of 0.1–0.2 eV. For the pentanes, the scattering cross sections on the low energy side of the minimum increase with increasing sphericity of the molecules, while the minimum tends to shift to higher energies. The same is true of the hexanes.

Acoustic Scattering Cross Sections of Smart Obstacles: A Case Study

2011 ◽  
Vol 10 (3) ◽  
pp. 672-694
Author(s):  
Lorella Fatone ◽  
Maria Cristina Recchioni ◽  
Francesco Zirilli
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Space Shuttle ◽  
Scattering Problem ◽  
Plane Waves ◽  
Acoustic Scattering ◽  
Scattering Cross Section ◽  
Scattering Cross ◽  
Scattering Cross Sections

AbstractAcoustic scattering cross sections of smart furtive obstacles are studied and discussed. A smart furtive obstacle is an obstacle that, when hit by an incoming field, avoids detection through the use of a pressure current acting on its boundary. A highly parallelizable algorithm for computing the acoustic scattering cross section of smart obstacles is developed. As a case study, this algorithm is applied to the (acoustic) scattering cross section of a “smart” (furtive) simplified version of the NASA space shuttle when hit by incoming time-harmonic plane waves, the wavelengths of which are small compared to the characteristic dimensions of the shuttle. The solution to this numerically challenging scattering problem requires the solution of systems of linear equations with many unknowns and equations. Due to the sparsity of these systems of equations, they can be stored and solved using affordable computing resources. A cross section analysis of the simplified NASA space shuttle highlights three findings: i) the smart furtive obstacle reduces the magnitude of its cross section compared to the cross section of a corresponding “passive” obstacle; ii) several wave propagation directions fail to satisfactorily respond to the smart strategy of the obstacle; iii) satisfactory furtive effects along all directions may only be obtained by using a pressure current of considerable magnitude. Numerical experiments and virtual reality applications can be found at the website: http://www.ceri.uniromal.it/ceri/zirilli/w7.

scholarly journals Analysis of the time-of-flight neutron scattering cross-section data for light water measured at the SEQUOIA spectrometer, Spallation Neutron Source (SNS)

2020 ◽  
Vol 239 ◽  
pp. 14007
Author(s):  
Vaibhav Jaiswal ◽  
Luiz Leal ◽  
Alexander I. Kolesnikov
Keyword(s):  
Cross Section ◽  
High Temperatures ◽  
Cross Sections ◽  
Scattering Cross Section ◽  
Spallation Neutron Source ◽  
Light Water ◽  
Section Data ◽  
Scattering Cross ◽  
Thermal Scattering ◽  
Scattering Cross Sections

Thermal neutron scattering cross-section data for light water available in the major nuclear data libraries observes significant differences especially at reactor operating temperatures. During the past few years there has been a renewed interest in reviewing the existing thermal scattering models and generating more accurate and reliable thermal scattering cross sections using existing experimental data and in some cases based on Molecular Dynamics (MD) simulations. There is a need for performing new time-of-flight experiments at high temperatures and pressures, to have a better understanding of the physics involved in the scattering process that could help improve the existing TSL data. Lack of experimental thermal scattering data for light water at high temperatures led to a new measurement campaign within the INSIDER project at the Institut de radioprotection et de sûreté nucléaire (IRSN). Double differential scattering cross section for light water have been measured at the SEQUOIA spectrometer based at the Spallation Neutron Source (SNS), Oak Ridge National Laboratory, United States. Several measurements have been carried out at different temperatures and pressures corresponding to liquid light water. Measurements at five different incident neutron energies Ei (8, 60, 160, 280 and 800 meV) have been carried out to help exploring different regions of the frequency spectrum. This paper presents the analysis of the dynamic structure factor and the derived frequency spectrum of light water. The analysis of the experimental data would provide one with better confidence, the behavior of thermal scattering cross sections for light water at high temperatures, knowledge of which is very important for the design of novel reactors as well as existing pressurized water reactors.

scholarly journals Absolute Differential Cross-Sections for Elastic Electron Scattering from Sevoflurane Molecule in the Energy Range from 50–300 eV

2021 ◽  
Vol 23 (1) ◽  
pp. 21
Author(s):  
Jelena Vukalović ◽  
Jelena B. Maljković ◽  
Francisco Blanco ◽  
Gustavo García ◽  
Branko Predojević ◽  
...  
Keyword(s):  
Cross Section ◽  
Electron Scattering ◽  
Cross Sections ◽  
Scattering Cross Section ◽  
Elastic Electron ◽  
Angular Range ◽  
Elastic Electron Scattering ◽  
Absolute Differential ◽  
Scattering Cross ◽  
The Absolute

We report the results of the measurements and calculations of the absolute differential elastic electron scattering cross-sections (DCSs) from sevoflurane molecule (C4H3F7O). The experimental absolute DCSs for elastic electron scattering were obtained for the incident electron energies from 50 eV to 300 eV, and for scattering angles from 25° to 125° using a crossed electron/target beams setup and the relative flow technique for calibration to the absolute scale. For the calculations, we have used the IAM-SCAR+I method (independent atom model (IAM) applying the screened additivity rule (SCAR) with interference terms included (I)). The molecular cross-sections were obtained from the atomic data by using the SCAR procedure, incorporating interference term corrections, by summing all the relevant atomic amplitudes, including the phase coefficients. In this approach, we obtain the molecular differential scattering cross-section (DCS), which, integrated over the scattered electron angular range, gives the integral scattering cross-section (ICS). Calculated cross-sections agree very well with experimental results, in the whole energy and angular range.

POLARIZED AND UNPOLARIZED INCLUSIVE ELECTRON SCATTERING IN NUCLEI AND THE INCLUSIVE NEUTRINO CROSS-SECTION

1995 ◽  
Vol 04 (01) ◽  
pp. 163-179
Author(s):  
S.L. MINTZ ◽  
M. POURKAVIANI
Keyword(s):  
Cross Section ◽  
Electron Scattering ◽  
Cross Sections ◽  
Inelastic Electron ◽  
Nuclear Excitation ◽  
Scattering Cross ◽  
Neutrino Cross Section ◽  
Inclusive Electron ◽  
Scattering Cross Sections ◽  
The Relationship

The unpolarized and parity violating polarized inclusive inelastic electron scattering cross-sections are calculated for incident electrons from threshold to 100 MeV, for the 12C nucleus. The relationship between these cross-sections and the inclusive neutrino cross-section on this same nucleus is discussed. The possibility of using the parity violating polarized electron scattering interaction to obtain the average nuclear excitation is also discussed.

scholarly journals Modeling of Scattering Cross Section for Mineral Aerosol with a Gaussian Beam

2018 ◽  
Vol 2018 ◽  
pp. 1-7 ◽  
Author(s):  
Wenbin Zheng ◽  
Hong Tang
Keyword(s):  
Gaussian Beam ◽  
Cross Section ◽  
Cross Sections ◽  
Scattering Cross Section ◽  
Nonspherical Particles ◽  
Red Clay ◽  
The Real ◽  
Scattering Cross ◽  
Mineral Aerosols ◽  
Scattering Cross Sections

Based on the generalized Lorenz Mie theory (GLMT), the scattering cross section of mineral aerosol within the Gaussian beam is investigated, and an appropriate modeling of the scattering cross sections for the real mineral aerosols including the feldspar, quartz, and red clay is proposed. In this modeling, the spheroid shape is applied to represent the real nonspherical mineral aerosol, and these nonspherical particles are randomly distributed within the Gaussian beam region. Meanwhile, the Monte Carlo statistical estimate method is used to determine the distributed positions of these random nonspherical particles. Moreover, a method for the nonspherical particles is proposed to represent the scattering cross section of the real mineral aerosols. In addition, the T matrix method is also used to calculate the scattering cross sections of the spheroid particles in order to compare the scattering properties between the plane wave and the Gaussian wave. Simulation results indicate that fairly reasonable results of the scattering cross sections for the mineral aerosols can be obtained with this proposed method, and it can provide a reliable and efficient approach to reproduce the scattering cross sections of the real randomly distributed mineral aerosols illuminated by the Gaussian beam.

Scattering Cross Sections in Electron Microscopy and Microanalysis

1999 ◽  
Vol 5 (S2) ◽  
pp. 672-673
Author(s):  
Peter Rez
Keyword(s):  
Electron Microscopy ◽  
Cross Section ◽  
Cross Sections ◽  
Unit Volume ◽  
Unit Area ◽  
Incident Beam ◽  
Scattering Cross Section ◽  
Scattering Cross ◽  
Scattering Cross Sections ◽  
Number Of Particles

In all scattering experiments some measure is need of the strength of the scattering interaction. The scattering cross section, which has dimensions of area, is a quantity that can be defined for any scattering interactions, irrespective of the nature of the scatterer, or the particle or radiation being scattered. To define a scattering cross section, refer to the geometry of Figure 1. If I0 is the incident number of particles, Is the number of particles scattered through an angle θ with an energy loss ΔE, N is the number of scatterers/ unit volume and t is the thickness of the specimen (or length of the scattering region) then where σ(θ ,ΔE) is the scattering cross section. The product N t represents the number of scatterers per unit area as seen by the incident beamIn electron microscopy all scattering arises from the Coulomb interaction between the incident electron and the electrons or nuclei or the atoms in the specimen.

Mass Determination by Direct Measurement of Electron Scattering

1975 ◽  
Vol 33 ◽  
pp. 240-241
Author(s):  
M. K. Lamvik ◽  
A. V. Crewe
Keyword(s):  
Cross Section ◽  
Electron Scattering ◽  
Mass Density ◽  
Variable Mass ◽  
Scattering Cross Section ◽  
Mass Determination ◽  
Number Density ◽  
Cross Sectional ◽  
Thin Slice ◽  
Scattering Cross

If a molecule or atom of material has molecular weight A, the number density of such units is given by n=Nρ/A, where N is Avogadro's number and ρ is the mass density of the material. The amount of scattering from each unit can be written by assigning an imaginary cross-sectional area σ to each unit. If the current I0 is incident on a thin slice of material of thickness z and the current I remains unscattered, then the scattering cross-section σ is defined by I=IOnσz. For a specimen that is not thin, the definition must be applied to each imaginary thin slice and the result I/I0 =exp(-nσz) is obtained by integrating over the whole thickness. It is useful to separate the variable mass-thickness w=ρz from the other factors to yield I/I0 =exp(-sw), where s=Nσ/A is the scattering cross-section per unit mass.

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