Study of a nested neutron-focusing supermirror system for small-angle neutron scattering

Wu, Huimeng; Yang, Yang; Hussey, Daniel S.; Wang, Zhiyuan; Song, Kun; Zhang, Zhong; Wang, Zhanshan; Wang, Xuewu

doi:10.1016/j.nima.2019.06.054

Cited by 11 publications

(6 citation statements)

References 23 publications

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“…However, large internal stress existing in the supermirror could result in the delamination of the coating from the surface of the substrate and thus degrade its physical structure. Meanwhile, for a nested neutron-focusing system (Yang et al, 2021;Wu et al, 2019), the supermirror must be coated on an ultra-thin glass substrate (0.3 mm) or Si wafers (Herb et al, 2022). If the stress of the film is excessively high, the substrate will be deformed and the optical performance of the focusing system will be affected.…”

Section: Internal Stressmentioning

confidence: 99%

Effect of the nitrogen content of sputtering gas during Ni deposition on Ni/Ti periodic multilayers and neutron supermirror performance

Zhang¹,

Zhong²,

Ni³

et al. 2023

J Appl Cryst

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Neutron supermirrors are indispensable in neutron research devices. Their performance has been improved using reactive magnetron sputtering. This study investigates the effects of nitrogen content in a mixed sputtering gas during Ni deposition. Ni/Ti periodic multilayers with different d spacings and neutron supermirrors with m = 3 were prepared under different nitrogen partial pressures. Comparison of samples prepared under two different nitrogen contents (12 and 20%) showed that the interfacial roughness and the internal stresses of the periodic multilayer films with 20% nitrogen were smaller, the interface diffusion of the supermirrors with 20% nitrogen decreased, and the interface became clearer and more organized. Furthermore, the neutron reflectivity of the Ni/Ti supermirrors deposited under 20% nitrogen was 0.89 at m = 3.05.

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Section: Internal Stressmentioning

confidence: 99%

Effect of the nitrogen content of sputtering gas during Ni deposition on Ni/Ti periodic multilayers and neutron supermirror performance

Zhang¹,

Zhong²,

Ni³

et al. 2023

J Appl Cryst

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“…The core component of the CPHS SANS spectrometer is multilayer-coated formed glass segmented optics which can be realized by prototype verification (Wu et al, 2019;Yang et al, 2021). The proposed approach to building these optics is to mount mirror shells on a hollow cylindrical mandrel, to form a nested fully annular focusing structure as shown in Fig.…”

Section: Determination Of Optimized Parametersmentioning

confidence: 99%

“…Gubarev et al (2007) also implemented nested Wolter mirrors coated with nickel to enhance the neutron current density by at least eight times for = 6-20 A ˚. In recent years, with nested conical integrated assembly technology that was initially applied in X-ray telescopes (Gondoin et al, 2000;Koglin et al, 2004;Wang et al, 2014;Shen et al, 2016) and supermirror coating technology, a prototype of two-shell nested fully annular quasi-ellipsoidal focusing mirrors with an m = 2 Ni/Ti supermirror coating was developed (Wu et al, 2019;Huang et al, 2012). This prototype was applied to a SANS spectrometer where the sample was placed between the mirrors and the image plane to enhance the beamline neutron current at the Tsinghua Compact Pulsed Hadron Source (CPHS) (Wu, 2020).…”

Section: Introductionmentioning

confidence: 99%

“…This prototype was applied to a SANS spectrometer where the sample was placed between the mirrors and the image plane to enhance the beamline neutron current at the Tsinghua Compact Pulsed Hadron Source (CPHS) (Wu, 2020). The test results demonstrated that the effective collecting area was 374 mm 2 and the neutron current was approximately 26 times higher than that with a pinhole design under the same Q min (Yang et al, 2021;Wu et al, 2019). However, the greater potential of nested focusing mirrors can be exploited further still by using additional nested shells and a larger m of the supermirror.…”

Section: Introductionmentioning

confidence: 99%

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Design of multi-shell nested fully annular quasi-ellipsoidal focusing mirrors for small-angle neutron scattering

Song,

Zhang,

Zhang

et al. 2023

J Appl Cryst

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The neutron flux is a crucial factor for neutron scattering measurements, especially for compact sources. Among various neutron optics, grazing-incidence focusing mirrors have been developed to give a significant increase in the neutron flux on a sample owing to their great potential for collecting neutrons in small-angle neutron scattering (SANS) instruments. Focusing mirrors with a supermirror coating can be nested to collect a neutron beam with large divergence. Nested conical integrated assembly technology is employed to manufacture nested focusing mirrors. This study describes the design of ten-shell nested fully annular quasi-ellipsoidal focusing mirrors with an m = 3 Ni/Ti supermirror coating to produce enough neutrons on a sample under the premise of satisfying the specified minimum wavevector transfer Q. For fully annular focusing mirrors, the neutron current received by a sample from the entire annular focusing neutron beam is more relevant. A ray-tracing method and current gain calculation are used to evaluate the performance of the designed mirrors. The ray-tracing result shows that the ideal resolution of quasi-ellipsoidal mirrors with four-segment conical approximation is 1.354 mm. As the source radius decreases from 20 mm, the neutron current with the designed focusing mirrors can be enhanced by a factor of 13 to over 100 compared with that without focusing mirrors in the same detected area. The effective collecting area is 186 cm2 when the source radius is the optimal 15 mm. An 83-fold current gain can be obtained for cold neutrons. The proposed mirrors can reach 90.7 and 87.3% of the maximum current of the corresponding optimal mirror structure when the source radii are 10 and 20 mm, respectively. The results demonstrate that the proposed mirrors are adaptable for instruments with changeable sources.

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“…On the other hand, toroidal mirror systems might ultimately be more efficient because they refocus neutrons in both dimensions simulta-neously by only a single reflection. However, the deposition of high-quality supermirrors directly on curved substrates seems technologically difficult [22]. In the limit of very short mirrors, where the elliptic curve can be approximated by a straight line, coating of flat substrates, subsequently bent into a final cylindrical geometry, might be a viable alternative if one can keep mirror waviness well under control.…”

Section: Operational Principle and Basic Implementations Of Nested El...mentioning

confidence: 99%

Nested mirror optics for neutron extraction, transport, and focusing

Herb¹,

Zimmer²,

Georgii³

et al. 2022

Preprint

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Neutron scattering is a well-established tool for the investigation of the static and dynamic properties of condensed matter systems over a wide range of spatial and temporal scales. Many studies of high interest, however, can only be performed on small samples and typically require elaborate environments for variation of parameters such as temperature, magnetic field and pressure. To improve the achievable signal-to-background ratio, focusing devices based on elliptic or parabolic neutron guides or Montel mirrors have been implemented. Here we report an experimental demonstration of a nested mirror optics (NMO), which overcomes some of the disadvantages of such devices. While even simpler than the original Wolter design, our compact assembly of elliptic mirrors images neutrons from a source to a target, minimizing geometric aberrations, gravitational effects and waviness-induced blurring. Experiments performed at MIRA at FRM-II demonstrate the expected focusing properties and a beam transport efficiency of 72 % for our first prototype. NMO seem particularly well-suited to i) extraction of neutrons from compact high-brilliance neutron moderators, ii) general neutron transport, and iii) focusing and polarizing neutrons. The phase space of the neutrons hitting a sample can be tailored on-line to the needed experimental resolution, resulting in small scattering backgrounds. As additional benefits, NMO situated far away from both the moderator and the sample are less susceptible to radiation damage and can easily be replaced. NMO enable a modular and physically transparent realization of beam lines for neutron physics similar to setups used in visible light optics.

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Study of a nested neutron-focusing supermirror system for small-angle neutron scattering

Cited by 11 publications

References 23 publications

Effect of the nitrogen content of sputtering gas during Ni deposition on Ni/Ti periodic multilayers and neutron supermirror performance

Effect of the nitrogen content of sputtering gas during Ni deposition on Ni/Ti periodic multilayers and neutron supermirror performance

Design of multi-shell nested fully annular quasi-ellipsoidal focusing mirrors for small-angle neutron scattering

Nested mirror optics for neutron extraction, transport, and focusing

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