scholarly journals Neutron scattering cross section of diamond nanoparticles

2019 ◽  
Vol 219 ◽  
pp. 10005
Author(s):  
Kenji Mishima ◽  
Toshiya Otomo ◽  
Kazutaka Ikeda ◽  
Hidetoshi Ohshita
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Coherent Scattering ◽  
Theoretical Description ◽  
Powder Sample ◽  
Scattering Cross Section ◽  
Hard Sphere Model ◽  
Particle Structure ◽  
Diamond Nanoparticles ◽  
Scattering Cross

Due to their large coherent scattering cross section, diamond nanoparticles (DNPs) are considered as a promising candidate material for a new neutron reflector. For investigation of scattering cross sections of packed samples, we have developed a technique for mechanical compression of DNP powder. Application of 220 MPa allowed us to increase the bulk density from 0.40 g/cm3 to 1.1 g/cm3. The differential cross sections of uncompressed and packed samples were measured using the high-intensity total diffractometer instrument NOVA at J-PARC, covering transfer wavenumbers (q) from 0.6 to 100 nm−1. The q dependence for the compressed sample agreed with the theoretical expectation derived from the Born approximation applied to homogeneous spheres with inclusion of a hard-sphere model to account for the inter-particle structure, whereas the results obtained from the powder sample disagreed. This implies that the theoretical description does not well represent the mesoscopic structure of the DNP powder sample.

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.

The 16O(p, γ)17F Direct Capture Cross Section with an Extrapolation to Astrophysical Energies

1975 ◽  
Vol 53 (17) ◽  
pp. 1672-1686 ◽  
Author(s):  
H. C. Chow ◽  
G. M. Griffiths ◽  
T. H. Hall
Keyword(s):  
Elastic Scattering ◽  
Excited States ◽  
Cross Section ◽  
Cross Sections ◽  
Capture Cross Section ◽  
Scattering Cross Section ◽  
Scattering Data ◽  
Capture Cross ◽  
Scattering Cross ◽  
Elastic Scattering Cross Section

The cross section for the direct radiative capture of protons by 16O has been measured relative to the proton elastic scattering cross section for energies from 800 to 2400 keV (CM). The elastic scattering cross section was normalized to the Rutherford scattering cross section at 385.5 keV. The capture cross section for the reaction 16O(p,γ)17F, which plays a role in hydrogen burning stars, has been extrapolated to stellar energies using a theoretical model which gives a good fit to the measured cross sections. The model involves calculation of electromagnetic matrix elements between initial and final state wave functions evaluated for Saxon–Woods potentials with parameters adjusted to fit both elastic scattering data and binding energies for the ground and first excited states of 17F. Cross sections for capture to the 5/2+ ground and 1/2+ first excited states of 17F in terms of astrophysical S factors valid for energies ≤ 100 keV have been found to be: S5/2+ = (0.317 + 0.0002E) keV b (± 8%); S1/2+ = (8.552 − 0.353E + 0.00013E2) keV b (± 5%).

Spin-Dependence of the Electron Scattering Cross Section by a Magnetic Layer System and the Magneto-Resistance

1998 ◽  
Vol 12 (29n31) ◽  
pp. 3376-3380 ◽  
Author(s):  
J. T. Wang ◽  
F. Tang ◽  
W. D. Brown ◽  
D. Bagayoko
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Magnetic Layer ◽  
Bulk Sample ◽  
Scattering Cross Section ◽  
Layer System ◽  
Interfacial Roughness ◽  
Scattering Cross ◽  
Experimental Findings ◽  
Magneto Resistance

We present a theoretical model for calculating the spin-dependent cross section of the scattering of electrons by a magnetic layer system. Our model demonstrates that the cross sections of the scattering are different for spin up and spin down electrons. The model assumes that the electrical resistivity in a conductor is proportional to the scattering cross section of the electron in it. It is believed to support the two channel mechanism in interpreting magneto-resistance (MR). Based on the model without considering the scattering due to the interfacial roughness and the spin flipping scattering, we have established a relationship between MR and the square of the magnetic moment in the bulk sample without considering the scattering due to the interfacial roughness and the spin flipping scattering. It can also qualitatively explain the MR difference between the current in plane (CIP) and current perpendicular to the plane (CPP) configurations. The predictions by the model agree well with the experimental findings.

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.

scholarly journals Monoenergetic Neutrons for Stellar Applications

2009 ◽  
Vol 26 (3) ◽  
pp. 232-236
Author(s):  
M. Mosconi ◽  
M. Heil ◽  
F. Käppeler ◽  
R. Plag ◽  
A. Mengoni ◽  
...  
Keyword(s):  
Inelastic Scattering ◽  
Cross Section ◽  
Cross Sections ◽  
Theoretical Calculations ◽  
Excited Level ◽  
Scattering Cross Section ◽  
Elastic Channel ◽  
Monoenergetic Neutron ◽  
Scattering Cross ◽  
Neutron Beams

AbstractWith modern techniques, neutron-capture cross sections can be determined with uncertainties of a few percent. However, Maxwellian averaged cross sections calculated from such data require a correction (because low-lying excited states are thermally populated in the hot stellar photon bath) which has to be determined by theoretical calculations. These calculations can be improved with information from indirect measurements, in particular by the inelastic scattering cross section. For low-lying levels, the inelastically scattered neutrons are difficult to separate from the dominant elastic channel. This problem is best solved by means of pulsed, monoenergetic neutron beams. For this reason, a pulsed beam of 30 keV neutrons with an energy spread of 7 to 9 keV FWHM and a width from 10 to 15 ns has been produced at Forschungszentrum Karlsruhe using the 7Li(p, n)7Be reaction directly at the reaction threshold. With this neutron beam the inelastic scattering cross section of the first excited level at 9.75 keV in 187Os was determined with a relative uncertainty of 6%. The use of monoenergetic neutron beams has been further pursued at the Physikalisch-Technische Bundesanstalt in Braunschweig, including the 3H(p, n)3He reaction for producing neutrons with an energy of 64 keV.

Test of Abnormally Large Coherent Scattering Cross Section Using Solar-Neutrino

1995 ◽  
Vol 12 (3) ◽  
pp. 136-139 ◽  
Author(s):  
Luo Jun ◽  
Chen Xiao ◽  
Li Jianguo ◽  
Fan Shuhua ◽  
Li Fangyu
Keyword(s):  
Cross Section ◽  
Solar Neutrino ◽  
Coherent Scattering ◽  
Scattering Cross Section ◽  
Scattering Cross
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