Präzise Bestimmung von freien Wirkungsquerschnitten für Neutronen / Precision Measurements of Free Cross Sections for Neutrons

1976 ◽  
Vol 31 (2) ◽  
pp. 115-122 ◽  
Author(s):  
W. Waschkowski ◽  
L. Koester
Keyword(s):  
Cross Sections ◽  
Resonance Energy ◽  
Statistical Error ◽  
Precision Measurements ◽  
Electron Interaction ◽  
Zero Energy ◽  
Liquid Samples ◽  
Resonance Energies ◽  
Neutron Cross Sections ◽  
Scattering Cross Sections

Rotating activation foils with resonance energies of 1.26 eV and 5.19 eV have been applied for exact measurements of neutron cross sections. The detector consisted of a sandwich of two rotating foils and was suitable for determining exactly the neutron flux at the resonance energy and energy changes in the neutron beam. The cross sections of polycrystalline samples showed uncertainties greater than the statistical error. The more accurate measurements on liquid samples yielded the following scattering cross sections of free atoms for neutrons of zero energy:Lead: σ0(Pb) = (11.261 ±0.006) b,Bismuth: σ0(Bi) = (9.300±0.003) b, andSulfur: σ0(S) = (0.985 ±0.004) b.These data are of interest for an investigation of the neutron-electron interaction.

Neutron Scattering in Materials Research

MRS Bulletin ◽  
1999 ◽  
Vol 24 (12) ◽  
pp. 14-16 ◽  
Author(s):  
T.E. Mason ◽  
A.D. Taylor
Keyword(s):  
Neutron Scattering ◽  
Cross Sections ◽  
Magnetic Moments ◽  
Biological Properties ◽  
Magnetic Interactions ◽  
Wide Range ◽  
Materials Research ◽  
Neutron Cross Sections ◽  
Scattering Cross Sections

With materials of ever-increasing complexity becoming key elements of the technologies underpinning industrial and economic development, there is an ongoing need for tools that reveal the microscopic origins of physical, electrical, magnetic, chemical, and biological properties. Neutron scattering is one such powerful tool for the study of the structure and dynamics of materials. Neutrons are well suited to this purpose for several reasons:∎ Neutrons are electrically neutral, leading to penetration depths of centimeters and thereby enabling in situ studies.∎ Neutron cross sections exhibit no regular dependence on atomic number and are similar in magnitude across the periodic table, giving rise to sensitivity to light elements in the presence of heavier ones.∎ Certain large differences in isotopic scattering cross sections (e.g., hydrogen to deuterium, H/D) make neutrons especially useful for the study of light atoms in materials.∎ The range of momentum transfer available allows probing of a broad range of length scales (0.1–105 Å), important in many different materials and applications.∎ Thermal and “cold” (longer-wavelength) neutrons cover a range of energies sufficient to probe a wide range of lattice or magnetic excitations, “slow” dynamic processes such as polymer chain reptation, and so forth.∎ Neutrons have magnetic moments and are thus uniquely sensitive probes of magnetic interactions.∎ Neutrons can be polarized, allowing the cross sections (magnetic and non-magnetic) to be separated.∎ The simplicity of the magnetic and nuclear interactions makes interpretation of results straightforward.

Absolute inner-shell cross section determination for EELS analysis

1988 ◽  
Vol 46 ◽  
pp. 534-535
Author(s):  
P.A. Crozier
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Absolute Cross Section ◽  
Specimen Thickness ◽  
Mass Thickness ◽  
Scattering Cross ◽  
Before And After ◽  
Estimated Error ◽  
Scattering Cross Sections ◽  
Electron Microscopist

Absolute inelastic scattering cross sections or mean free paths are often used in EELS analysis for determining elemental concentrations and specimen thickness. In most instances, theoretical values must be used because there have been few attempts to determine experimental scattering cross sections from solids under the conditions of interest to electron microscopist. In addition to providing data for spectral quantitation, absolute cross section measurements yields useful information on many of the approximations which are frequently involved in EELS analysis procedures. In this paper, experimental cross sections are presented for some inner-shell edges of Al, Cu, Ag and Au.Uniform thin films of the previously mentioned materials were prepared by vacuum evaporation onto microscope cover slips. The cover slips were weighed before and after evaporation to determine the mass thickness of the films. The estimated error in this method of determining mass thickness was ±7 x 107g/cm2. The films were floated off in water and mounted on Cu grids.

scholarly journals Undergraduate Measurements of Neutron Cross Sections

2015 ◽  
Vol 66 ◽  
pp. 641-648 ◽  
Author(s):  
S.F. Hicks ◽  
J.R. Vanhoy ◽  
A.J. French ◽  
Z.C. Santonil ◽  
B.P. Crider ◽  
...  
Keyword(s):  
Cross Sections ◽  
Neutron Cross Sections

scholarly journals Towards fully nonperturbative computations of inelastic ℓN scattering cross sections from lattice QCD

2020 ◽  
Vol 102 (11) ◽  
Author(s):  
Hidenori Fukaya ◽  
Shoji Hashimoto ◽  
Takashi Kaneko ◽  
Hiroshi Ohki
Keyword(s):  
Lattice Qcd ◽  
Cross Sections ◽  
Scattering Cross ◽  
Scattering Cross Sections

scholarly journals Combining ADF-EDX scattering cross-sections for elemental quantification of nanostructures

2021 ◽  
Vol 27 (S1) ◽  
pp. 600-602
Author(s):  
Zezhong Zhang ◽  
Annick De Backer ◽  
Ivan Lobato ◽  
Sandra Van Aert ◽  
Peter Nellist
Keyword(s):  
Cross Sections ◽  
Scattering Cross ◽  
Scattering Cross Sections

Neutron diffraction, inelastic scattering and the structure of amphiphiles and macromolecules in solution

1975 ◽  
Vol 345 (1640) ◽  
pp. 119-144 ◽  
Keyword(s):  
Neutron Diffraction ◽  
Inelastic Scattering ◽  
Cross Sections ◽  
Biological Molecules ◽  
Variation Method ◽  
Contrast Variation ◽  
Structure And Dynamics ◽  
Spin Resonance ◽  
Scattering Lengths ◽  
Scattering Cross Sections

The methods by which neutron diffraction and inelastic scattering may be used to study the structure and dynamics of solutions are reviewed, with particular reference to solutions of amphiphile and biological molecules in water. Neutron methods have particular power because the scattering lengths for protons and deuterons are of opposite sign, and hence there exists the possibility of obtaining variable contrast between the scattering of the aqueous medium and the molecules in it. In addition, the contrast variation method is also applicable to inelastic scattering studies whereby the dynamics of one component of the solution can be preferentially studied due to large and variable differences in the scattering cross sections. Both applications of contrast variation are illustrated with examples of amphiphile-water lamellar mesophases, diffraction from collagen, viruses, and polymer solutions. Inelastic scattering observations and the dynamics of water between the lamellar sheets allow microscopic measurements of the water diffusion along and perpendicular to the layers. The information obtained is complementary to that from nuclear magnetic resonance and electron spin resonance studies of diffusion.

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