Insight into neutron focusing: the out-of-focus condition

2013 ◽  
Vol 46 (5) ◽  
pp. 1361-1371 ◽  
Author(s):  
B. Hammouda ◽  
D. F. R. Mildner ◽  
A. Brûlet ◽  
S. Desert
Keyword(s):  
Standard Deviation ◽  
Neutron Scattering ◽  
Small Angle ◽  
Small Angle Neutron Scattering ◽  
Neutron Wavelength ◽  
Focus Condition ◽  
The Mean ◽  
The Individual ◽  
Multiple Holes ◽  
Good Agreement

Neutron focusing leads to significant gains in flux-on-sample in small-angle neutron scattering and very small angle neutron scattering instruments. Understanding the out-of-focus condition is necessary for less than optimal conditions such as for short instruments and low neutron wavelengths. Neutron focusing is investigated using a three-pronged approach. The three methods are analytical calculations, resolution measurements and computer simulations. A source aperture containing a single small-size hole and a sample aperture containing multiple holes are used to produce multiple spots on the high-resolution neutron detector. Lens focusing elongates off-axis spots in the radial direction. The standard deviation for the size of each spot is estimated using these three approaches. Varying parameters include the neutron wavelength, the number of focusing lenses and the location of holes on the sample aperture. Enough agreement for the standard deviation of the individual neutron beams was found between the calculations and the measurements to give confidence in this approach. Good agreement was found between the standard deviations obtained from calculations and simulations as well. Excellent agreement was found for the mean location of these individual spots.

Comparison of Small-Angle Neutron Scattering of δ' Precipitation in an Al–Li Alloy at a High-Flux Reactor and at a Pulsed-Neutron Source

1997 ◽  
Vol 30 (5) ◽  
pp. 602-606 ◽  
Author(s):  
G. Albertini ◽  
F. Carsughi ◽  
R. Coppola ◽  
R. K. Heenan ◽  
M. Stefanon
Keyword(s):  
Neutron Scattering ◽  
Small Angle ◽  
Small Angle Neutron Scattering ◽  
Size Distribution Function ◽  
Data Sets ◽  
Flux Reactor ◽  
Average Size ◽  
Pulsed Neutron ◽  
Pulsed Neutron Source ◽  
Good Agreement

Two different small-angle neutron scattering (SANS) facilities, the D11 camera at the Institut Laue–Langevin (ILL, Grenoble, France) and the LOQ time-of-flight diffractometer at the Rutherford Appleton Laboratory (RAL, Didcot, Oxon, England), were used in the investigations of δ′-Al3Li precipitation at 463 K in Al–Li 3% alloy. The results obtained from the steady-state reactor and from the pulsed source by using two different data-acquisition techniques and two different procedures for data analysis are compared. The SANS curves for the same set of samples investigated using the two different instruments are in good agreement within the experimental uncertainties. A check was also made on the metallurgically relevant quantities, namely the average size and the size-distribution function of the δ′ precipitates at the various stages of the ageing process, obtained from the two sets of SANS curves by applying the same numerical method. Good agreement was found between the results from the two data sets.

Autocorrelation function of the spin misalignment in magnetic small-angle neutron scattering: application to nanocrystalline metals

2013 ◽  
Vol 46 (3) ◽  
pp. 788-790 ◽  
Author(s):  
Andreas Michels ◽  
Jens-Peter Bick
Keyword(s):  
Neutron Scattering ◽  
Autocorrelation Function ◽  
Small Angle ◽  
Small Angle Neutron Scattering ◽  
Anisotropy Field ◽  
Real Space ◽  
Scattering Data ◽  
Stiffness Constant ◽  
The Mean ◽  
Cobalt And Nickel

Real-space magnetic small-angle neutron scattering data from nanocrystalline cobalt and nickel have been analysed in terms of a recently developed micromagnetic theory for the autocorrelation function of the spin misalignment [Michels (2010).Phys. Rev. B,82, 024433]. The approach provides information on the exchange-stiffness constant and on the mean magnetic `anisotropy-field' radius.

Toward a new lower limit for the minimum scattering vector on the very small angle neutron scattering spectrometer at Laboratoire Léon Brillouin

2008 ◽  
Vol 41 (1) ◽  
pp. 161-166 ◽  
Author(s):  
Annie Brûlet ◽  
Vincent Thévenot ◽  
Didier Lairez ◽  
Sébastien Lecommandoux ◽  
Willy Agut ◽  
...  
Keyword(s):  
Neutron Scattering ◽  
Small Angle ◽  
Small Angle Neutron Scattering ◽  
Pixel Size ◽  
Resolution Function ◽  
Incident Wavelength ◽  
Under Construction ◽  
Very High ◽  
Good Agreement ◽  
Small Pixel

The main characteristics of the very small angle neutron scattering spectrometer (VSANS) under construction at the Laboratoire Léon Brillouin are a multibeam pinhole collimator converging onto an image plate detector. By combining tiny collimation (diaphragms of around 1 or 2 mm in diameter) with the small pixel size of the detector (0.15 × 0.15 mm), very high resolution measurements can be achieved. The resolution function of the instrument contains a contribution from gravity, which is reduced by the intermediate masks of the collimator. Owing to the relatively short length of the VSANS instrument (around 14 m), this effect remains weak, in good agreement with the predictions. With a prototype multibeam collimator, an incident wavelength of 0.9 nm and the detector located at 6 m from the sample, it is possible to accessqvalues as low as 4 × 10−3 nm−1with very highqresolution. Promising preliminary experiments with highqresolution are reported, which open up new fields to the SANS technique.

scholarly journals Soft particles in an electric field – a zero average contrast study

Soft Matter ◽  
2019 ◽  
Vol 15 (31) ◽  
pp. 6369-6374 ◽  
Author(s):  
Sofi Nöjd ◽  
Christopher Hirst ◽  
Marc Obiols-Rabasa ◽  
Julien Schmitt ◽  
Aurel Radulescu ◽  
...  
Keyword(s):  
Electric Field ◽  
Neutron Scattering ◽  
External Electric Field ◽  
Small Angle ◽  
Small Angle Neutron Scattering ◽  
Contrast Study ◽  
Soft Particles ◽  
Average Contrast ◽  
The Individual ◽  
Individual Particles

Small-angle neutron scattering experiments on microgels provide information about the response of the individual particles to an external electric field.

scholarly journals First Experiment of Spin Contrast Variation Small-Angle Neutron Scattering on the iMATERIA Instrument at J-PARC

2020 ◽  
Vol 4 (4) ◽  
pp. 33 ◽  
Author(s):  
Yohei Noda ◽  
Tomoki Maeda ◽  
Takayuki Oku ◽  
Satoshi Koizumi ◽  
Tomomi Masui ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Neutron Scattering ◽  
Small Angle ◽  
Small Angle Neutron Scattering ◽  
Coherent Scattering ◽  
Proton Spin ◽  
Neutron Polarization ◽  
Stray Magnetic Field ◽  
Beam Experiment ◽  
Neutron Wavelength

Recently, we have developed a novel dynamic nuclear polarization (DNP) apparatus with a magnetic field of 7 T and a sample temperature of 1 K. High proton spin polarizations from −84% to 76%, for TEMPO doped polystyrene samples, have been demonstrated. This DNP apparatus satisfies the simultaneous requirement for quick and easy sample exchange and high DNP performance. On the iMATERIA (BL20) instrument at J-PARC, the first beam experiment using this DNP apparatus has been performed. For this experiment, the beamline was equipped with a supermirror polarizer. The stray magnetic field due to the superconducting magnet for DNP was also evaluated. The stray magnetic field plays an important role for in maintaining the neutron polarization during the transportation from the polarizer to the sample. The small-angle neutron scattering (SANS) profiles of silica-filled rubber under dynamically polarized conditions are presented. By applying our new analytical approach for SANS coherent scattering intensity, neutron polarization (PN) as a function of neutron wavelength was determined. Consequently, for the neutron wavelength, range from 4 Å to 10 Å, |PN| was sufficient for DNP-SANS studies.

scholarly journals Simulations of foil-based spin-echo (modulated) small-angle neutron scattering with a sample using McStas

2021 ◽  
Vol 54 (1) ◽  
pp. 195-202
Author(s):  
Wim G. Bouwman ◽  
Erik B. Knudsen ◽  
Linda Udby ◽  
Peter Willendrup
Keyword(s):  
Magnetic Field ◽  
Elastic Scattering ◽  
Neutron Scattering ◽  
Small Angle ◽  
Small Angle Neutron Scattering ◽  
Spin Echo ◽  
Transmitted Beam ◽  
Further Development ◽  
Theory And Experiments ◽  
Good Agreement

For the further development of spin-echo techniques to label elastic scattering it is necessary to perform simulations of the Larmor precession of neutron spins in a magnetic field. The details of some of these techniques as implemented at the reactor in Delft are simulated. First, the workings of the magnetized foil flipper are simulated. A full virtual spin-echo small-angle neutron scattering instrument is built and tested without and with a realistic scattering sample. It is essential for these simulations to have a simulated sample that also describes the transmitted beam of unscattered neutrons, which usually is not implemented for the simulation of conventional small-angle neutron scattering (SANS) instruments. Finally, the workings of a spin-echo modulated small-angle neutron scattering (SEMSANS) instrument are simulated. The simulations are in good agreement with theory and experiments. This setup can be extended to include realistic magnetic field distributions to fully predict the features of future Larmor labelling elastic-scattering instruments. Configurations can now be simulated for more complicated combinations of SANS with SEMSANS.

Resolution functions of time-of-flight small-angle neutron scattering instruments with rectangular apertures

2007 ◽  
Vol 40 (1) ◽  
pp. 40-50 ◽  
Author(s):  
B. Grabcev
Keyword(s):  
Gravitational Field ◽  
Elastic Scattering ◽  
Neutron Scattering ◽  
Small Angle ◽  
Small Angle Neutron Scattering ◽  
Time Of Flight ◽  
Careful Analysis ◽  
Mathematical Relationship ◽  
Angle Scattering ◽  
Neutron Wavelength

Analytic forms are found for resolution functions of small-angle neutron scattering instruments. The expressions are developed as a function of momentum transfer (Q) rather than separately in terms of neutron wavelength (λ) and scattering angle (θ). Effects caused by the gravitational field as well as by quasi-elastic scattering are included. Explicit analytic forms for the transmission functions are proposed for both the incident and scattered beams, enabling careful analysis of any problem regarding small-angle scattering experiments. Due to the reciprocal mathematical relationship between λ, θ andQ, [λ, θ] space is employed to approach different aspects of the topic. Applications to time-of-flight instruments with rectangular apertures, including the choice of the most convenient instrumental parameters, the analysis of smearing effects and the data reduction toQspace, are presented.

A Chord Distribution Description of Porous Glass

1990 ◽  
Vol 195 ◽  
Author(s):  
M. Y. Lin ◽  
S. K. Sinha
Keyword(s):  
Porous Medium ◽  
Neutron Scattering ◽  
Porous Glass ◽  
Small Angle ◽  
Small Angle Neutron Scattering ◽  
Capillary Condensation ◽  
Scattering Data ◽  
Distribution Model ◽  
Microporous Structure ◽  
Good Agreement

ABSTRACTSmall angle neutron scattering data of Vycor is analyzed using a chord distribution model describing the microporous structure. In addition, the same model is applied in interpreting the data taken when capillary condensation takes place in the porous medium. In both cases, the results are in good agreement with other measurements, and shows a promising potential in describing such a bicontinuous system.

SANS

2018 ◽  
Author(s):  
Eaton E. Lattman ◽  
Thomas D. Grant ◽  
Edward H. Snell
Keyword(s):  
Neutron Scattering ◽  
Small Angle ◽  
Biological Samples ◽  
Small Angle Neutron Scattering ◽  
Structural Studies ◽  
Unique Information ◽  
The Individual ◽  
Contrast Matching

Small angle neutron scattering (SANS) is a specialized application of solution scattering limited by source availability and intensity. While not routinely used for structural studies of biological samples in general, it does have unique characteristics that make it attractive to determining the individual positions of components of complexes. This is due to the scattering properties of hydrogen and deuterium allowing the technique of contrast matching. SANS is highly complementary to SAXS and provides unique information not available by other techniques. This chapter discussed SANS, instrumentation, and application.

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