Development and prospects of Very Small Angle Neutron Scattering (VSANS) techniques

Zuo, Taisen; Cheng, He; Chen, Yuanbo; Wang, Fangwei

doi:10.1088/1674-1137/40/7/076204

Cited by 15 publications

(9 citation statements)

References 57 publications

(91 reference statements)

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“…This spallation neutron source is selected with a repetition frequency of 25 Hz [30] . In order to increase the neutron flux and reduce simulation time, the divergence of the source was calculated using the distance between the two slits and that between slit 2 and the detector [31] . The distance between the sample and the detector is 6 m, equal to that between the two slits.…”

Section: Virtual Neutron Experimentsmentioning

confidence: 99%

Data reduction for time-of-flight small-angle neutron scattering with virtual neutrons

Tian

Zuo

et al. 2017

Instrumentation Science & Technology

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Abstract:Small-angle neutron scattering (SANS) is an experimental technique to detect material structures in the nanometer to micrometer range. The solution of the structural model constructed from SANS strongly depends on the accuracy of the reduced data. The time-offlight (TOF) SANS data are dependent on the wavelength of the pulsed neutron source.Therefore, data reduction must be handled very carefully to transform measured neutron events into neutron scattering intensity. In this study, reduction algorithms for TOF SANS data are developed and optimized using simulated data from a virtual neutron experiment. Each possible effect on the measured data is studied systematically, and suitable corrections are performed to obtain high-quality data. This work will facilitate scientific research and the instrument design at China Spallation Neutron Source.

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Section: Virtual Neutron Experimentsmentioning

confidence: 99%

Data reduction for time-of-flight small-angle neutron scattering with virtual neutrons

Tian

Zuo

et al. 2017

Instrumentation Science & Technology

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“…The most feasible technique for focusing a white neutron beam at a spallation source up to now has been the use of multi-slit collimators (Zuo et al, 2016). The concepts of multichannel collimator converging diaphragms or Soller collimators to upgrade traditional SANS instruments were proposed in the 1970s by Nunes, Carpenter and co-workers (Nunes, 1974;Carpenter & Faber, 1978).…”

Section: Introductionmentioning

confidence: 99%

The multi-slit very small angle neutron scattering instrument at the China Spallation Neutron Source

Zuo,

Han,

et al. 2024

J Appl Crystallogr

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A multi-slit very small angle neutron scattering (MS-VSANS) instrument has been finally accepted at the China Spallation Neutron Source (CSNS). It is the first spallation neutron source based VSANS instrument. MS-VSANS has a good signal-to-noise ratio and can cover a wide scattering vector magnitude range from 0.00028 to 1.4 Å−1. In its primary flight path, a combined curved multichannel beam bender and sections of rotary exchange drums are installed to minimize the background downstream of the instrument. An exchangeable multi-slit beam focusing system is integrated into the primary flight path, enabling access to a minimum scattering vector magnitude of 0.00028 Å−1. MS-VSANS has three modes, namely conventional SANS, polarizing SANS and VSANS modes. In the SANS mode, three motorized high-efficiency 3He tube detectors inside the detector tank cover scattering angles from 0.12 to 35° simultaneously. In the polarizing SANS mode, a double-V cavity provides highly polarized neutrons and a high-efficiency 3He polarization analyser allows full polarization analysis. In the VSANS mode, an innovative high-resolution gas electron multiplier detector covers scattering angles from 0.016 to 0.447°. The absolute scattering intensities of a selection of standard samples are obtained using the direct-beam technique; the effectiveness of this method is verified by testing the standard samples and comparing the results with those from a benchmark instrument. The MS-VSANS instrument is designed to be flexible and versatile and all the design goals have been achieved.

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“…In an effort to search the molecular mechanism of the complex crystallization and phase transition behavior as well as its superior mechanical properties in relation to chain conformations, preparation of a deuterated labeled chain followed by a neutron scattering investigation is the most straightforward way. 28−31 With the development of the small angle neutron scattering (SANS) technique, 32,33 the deuterium (D)-substitution method is gradually becoming a powerful tool for the study of a series of issues such as phase behavior, chain structure, crystal morphology, and orientation of polymeric materials, especially macromolecule alloys and copolymers. 34−43 However, before deuterated chains can be used as isotopic markers, one needs to determine whether their alldeuterated polymers have the same or similar intrinsic properties (physical and chemical) as conventional systems.…”

Section: ■ Introductionmentioning

confidence: 99%

Deuterated Isotactic Polybutene-1 Exhibits Fast Form II to I Transition at Isothermal Crystallization Temperatures

Zhao,

Jian

et al. 2024

Macromolecules

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Deuterated isotactic polybutene-1 (dPB-1) (M w : 349 kg/mol) and its hydrogeneous counterpart (hPB-1) (M w : 346 kg/mol) have been synthesized using deuterated 1-butene and hydrogeneous 1-butene monomers, respectively. The dPB-1 shows similar crystallization habit as hPB-1, i.e., crystallizing into metastable form II, which then transforms into stable form I. This peculiar polymorphic transition in hPB-1 normally occurs after cooling to lower temperatures after the crystallization of form II crystals because an internal stress along the lamellar normal built-up during cooling helps to overcome the nucleation barrier of the transition. Surprisingly, a spontaneous form II to I transition at the isothermal crystallization temperature is observed in dPB-1. The crystallization kinetics of form II in dPB-1 is essentially similar to that of hPB-1. The kinetics of the II to I transition in dPB-1 at the isothermal crystallization temperature exhibits a two-step process with the first one with kinetics nearly the same as the crystallization and the second one much slower. The results indicate a very low overall free energy barrier for the II to I transition in dPB-1 suggesting a critical role of the amorphous phase. Indeed, unlike in hPB-1 the conformational energy of 3/1helix in form I is even slightly higher than the 11/3 helix in form II in dPB-1 meaning that the driving force for the II to I transition from inside the crystalline phase is at most similar in both hPB-1 and dPB-1. It turns out that the entropy in the amorphous phase of the dPB-1 is much lower than that of hPB-1 because the vibrational entropy of bonds in both systems is largely different. As such, a much smaller free energy barrier is obtained for the II to I transition in dPB-1 so that a spontaneous transition is observed.

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Development and prospects of Very Small Angle Neutron Scattering (VSANS) techniques

Cited by 15 publications

References 57 publications

Data reduction for time-of-flight small-angle neutron scattering with virtual neutrons

Data reduction for time-of-flight small-angle neutron scattering with virtual neutrons

The multi-slit very small angle neutron scattering instrument at the China Spallation Neutron Source

Deuterated Isotactic Polybutene-1 Exhibits Fast Form II to I Transition at Isothermal Crystallization Temperatures

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