Small-angle neutron scattering spectrometer Suanni equipped with ultra-thin biconcave focusing lenses

2016 ◽  
Vol 49 (4) ◽  
pp. 1388-1393 ◽  
Author(s):  
Liang Chen ◽  
Liangwei Sun ◽  
Yun Wang ◽  
Yunlong Wang ◽  
Lin Zou ◽  
...  
Keyword(s):  
Neutron Scattering ◽  
Small Angle ◽  
Small Angle Neutron Scattering ◽  
Research Reactor ◽  
Cold Neutron ◽  
Gain Factor ◽  
Beam Size ◽  
Cold Neutron Source ◽  
Neutron Wavelength ◽  
Order Of Magnitude

The small-angle neutron scattering (SANS) spectrometer Suanni at the liquid hydrogen cold neutron source of the 20 MW China Mianyang Research Reactor has recently been upgraded. Ultra-thin biconcave MgF2lenses with a central thickness down to 0.2 mm have been installed between the collimator chamber and the sample stage. The lenses are able to improve the flux without too excessive an increase in the neutron beam size on the detector. A smaller minimumQ(Qmin) can be obtained by decreasing the beam size without changing the total length of the spectrometer. By testing the central beam profiles under different neutron wavelengths (∼0.56–1 nm) with both traditional pinhole SANS (PSANS) and focusing SANS (FSANS) geometries, the gain factor thanks to the neutron lenses is about one order of magnitude. Given the loss of intensity due to the absorption of neutrons by the lenses, the benefits of the focusing can only be realized if it is possible to increase the aperture size. With an identical source aperture, FSANS can minimize the nominalQminfrom 7.20 × 10−3 nm−1(for PSANS) to 5.55 × 10−3 nm−1at a neutron wavelength of 1 nm. The practical benefit provided by the lenses is verified with a solution of poly(methyl methacrylate) nanospheres, which yields a scattering intensity one order of magnitude higher and a better resolution with the FSANS geometry than with that of PSANS.

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.

The small-angle neutron scattering spectrometer at the University of Missouri research reactor

1981 ◽  
Vol 14 (6) ◽  
pp. 370-382 ◽  
Author(s):  
D. F. R. Mildner ◽  
R. Berliner ◽  
O. A. Pringle ◽  
J. S. King
Keyword(s):  
Neutron Scattering ◽  
Small Angle ◽  
Small Angle Neutron Scattering ◽  
Research Reactor ◽  
Pyrolytic Graphite ◽  
Flight Path ◽  
University Of Missouri ◽  
Beam Incident ◽  
Position Sensitive ◽  
The University

A small-angle neutron scattering (SANS) spectrometer has been constructed at the University of Missouri Research Reactor Facility (MURR). The design of the MURR–SANS is unusual in that the size of the reactor containment building constrains the flight path to be vertical. This is achieved by Bragg scattering upward through 90° from a set of slightly misaligned pyrolytic graphite crystals to provide a neutron beam at 4.75 Å with a wavelength spread of approximately 4.1%. The beam incident on the sample is defined by two matched variable apertures located either 3.0 or 4.5 m apart. The evacuated scattered flight path is designed with removable extensions to match the primary flight path in length. The instrument has an automatic sample handling capability provided by its own dedicated PDP 11/03 computer. The detector is a large assembly of commercially available linear 3He detectors as an economic alternative to a crossed-wire two-dimensional multi-detector. An array of 43 position-sensitive proportional counters, 24 in (609.6 mm) long and 0.5 in (12.7 mm) in diameter, using charge division gives a spatial resolution of 5 x 12.7 mm. The area-averaged detector efficiency is about 84% at a wavelength of 4.75 Å. The range of scattering vectors that can be measured is 0.005 < Q< 0.15 Å−1. The instrument is well suited to a wide variety of experiments on specimens having characteristic dimensions between 20 and 500 Å. MURR–SANS is designed as a user-oriented facility which provides both reasonable resolution and intensity on sample at a modest cost, and forms part of a neutron scattering center.

Multiple small-angle neutron scattering characterization of the densification of ceramics: application to microporous silica

1989 ◽  
Vol 22 (6) ◽  
pp. 539-545 ◽  
Author(s):  
G. G. Long ◽  
S. Krueger
Keyword(s):  
Neutron Scattering ◽  
Small Angle ◽  
Small Angle Neutron Scattering ◽  
Mercury Porosimetry ◽  
Porous Silica ◽  
Bimodal Distribution ◽  
Scattering Method ◽  
Microporous Silica ◽  
Order Of Magnitude ◽  
Multiple Scattering Method

Multiple small-angle neutron scattering was used to characterize the microstructure evolution of porous silica as a function of thermal processing. This new technique offers a statistically significant determination of microstructure morphology in the 0.08–10 μm range, which was previously inaccessible without increasing the resolution of the currently available scattering spectroscopy beamlines. All of the scatterers, which in the present work are pores within ceramic bodies, are measured whether they are open or closed. Earlier mercury porosimetry and nitrogen desorption measurements of the microporous silica system indicated that there are two major populations of pores in this material, differing in pore size by approximately an order of magnitude. In this work, it was found that densification during the intermediate stages of sintering is accompanied by coarsening to radii > 0.22 μm within the population of large pores in microporous silica. In the late stages of sintering, there are no detectable pores with radii > 0.08 μm, and radii of gyration equal to 33 and 28 nm were measured. Finally, Monte Carlo simulations were carried out to complement the neutron-scattering measurements, to predict the influence on the results of the bimodal distribution, and to explore the sensitivity of the multiple-scattering method.

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.

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.

On the design and experimental realization of a multislit-based very small angle neutron scattering instrument at the European Spallation Source

2015 ◽  
Vol 48 (4) ◽  
pp. 1242-1253 ◽  
Author(s):  
Sohrab Abbas ◽  
Sylvain Désert ◽  
Annie Brûlet ◽  
Vincent Thevenot ◽  
Patrice Permingeat ◽  
...  
Keyword(s):  
Neutron Scattering ◽  
Small Angle ◽  
Small Angle Neutron Scattering ◽  
Feasibility Studies ◽  
Experimental Realization ◽  
Order Of Magnitude ◽  
Spallation Source ◽  
Length Scaling ◽  
First Time ◽  
Sans Instrument

This article reports the design of a versatile multislit-based very small angle neutron scattering (VSANS) instrument working either as a dedicated instrument or as an add-on for any small-angle neutron scattering machine like the proposed SANS instrument, SKADI, at the future European Spallation Source. The use of multiple slits as a VSANS collimator for the time-of-flight techniques has been validated usingMcStassimulations. Various instrument configurations to achieve different minimum wavevector transfers in scattering experiments are proposed. The flexibility of the multislit VSANS instrument concept is demonstrated by showing the possibility of instrument length scaling for the first time, allowing access to varying minimum wavevector transfers with the same multislit setup. These options can provide smooth access to minimum wavevector transfers lower than ∼4 × 10−5 Å−1and an overlapping of wavevector coverage with normal SANS mode,e.g.with the SKADI wavevector range of 10−3–1.1 Å−1. Such an angularly well defined and intense neutron beam will allow faster SANS studies of objects larger than 1 µm. Calculations have also been carried out for a radial collimator as an alternative to the multislit collimator setup. This extends the SANSQrange by an order of magnitude to 1 × 10−4 Å−1with much simpler alignment. The multislit idea has been realized experimentally by building a prototype at Laboratoire Leon Brillouin, Saclay, with cross-talk-free geometry. Feasibility studies were carried out by making VSANS measurements with single- and multislit collimators, and the results are compared with multiple-pinhole geometry using classical SANS analysis tools.

Novel multiple-beam very small angle neutron scattering (VSANS) using a conventional SANS instrument

2014 ◽  
Vol 47 (4) ◽  
pp. 1180-1189 ◽  
Author(s):  
C. D. Dewhurst
Keyword(s):  
Neutron Scattering ◽  
Small Angle ◽  
Neutron Detector ◽  
Small Angle Neutron Scattering ◽  
Single Scattering ◽  
Small Samples ◽  
Neutron Guide ◽  
Multiple Beam ◽  
Order Of Magnitude ◽  
Sans Instrument

This article demonstrates how a small-angle neutron scattering (SANS) instrument, such as D33 at the Institut Laue–Langevin, can be configured without extensive modification to produce multiple highly collimated beams for measurements at the smallest scattering angles. This extends the range of material length scales able to be studied to greater than 1 µm, almost one order of magnitude greater than that of a conventional SANS instrument. The multiple-beam configuration uses the intrinsic properties of the neutron guide system and source and sample apertures with no additional optical devices or precise aperture array alignments. Up to several hundred individual beams, separated in angle by fractions of a degree in both the horizontal and vertical directions, can be extracted, which focus at the sample and diverge towards the distant neutron detector. This is particularly useful for the study of small samples, which can be probed at the smallest scattering angles while retaining sufficient neutron flux because of the use of multiple beams. The resulting data on the area neutron detector consist of multiple scattering or diffraction images which extend over and overlap those produced by neighboring beams. While the principle of the technique is rather simple, analysis of the overlapping SANS patterns requires the development of software techniques to extract the single scattering function.

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