&lt;title&gt;Reflectivity improvements for neutron mirrors and supermirrors&lt;/title&gt;

Vidal, Bernard; Samuel, F.

doi:10.1117/12.130617

Cited by 15 publications

(5 citation statements)

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“…Other optimisation procedures have been discussed by Vidal et al 8 and Joensen et aP. In particular, Loevezijn et al 1° have descibed an optimisation method that can be used to generate specified bandpasses for the soft X-ray range.…”

Section: Introductionmentioning

confidence: 98%

<title>Optimization of depth-graded multilayer designs for EUV and x-ray optics</title>

Wang

Michette

2001

Advances in X-Ray Optics

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The optimisation ofthe design of depth-graded multilayers with special angular or wavelength responses for use as coatings in EUV/Xray optics is discussed in this presentation. The optimisation is based on the well4cnown Fresnel equations and recursive calculation combined with a defmed merit function, with random variation of the thickness of each layer. The optimisation of depth-graded multilayers for various applications uses a process that judges a design based on its required performance in a given range of wavelength and/or incidence angle. The requirements could include many factors such as the spectral distribution of a source, the shape of the reflectivity curve or the geometry of the optical system. The key factor for optimisation is to determine a suitable merit function for a specific application. This allows the design of multilayers for different requirements. The method has been used to give the thickness of each layer in some depth-graded multilayers with special requirements in optical properties.

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Section: Introductionmentioning

confidence: 98%

<title>Optimization of depth-graded multilayer designs for EUV and x-ray optics</title>

Wang

Michette

2001

Advances in X-Ray Optics

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“…The signal-to-background ratio has been increased through the implementation of neutron-focusing elements based on elliptic/parabolic neutron guides or Montel mirrors. Furthermore, the reflectivity of neutron optics can be effectively improved by coating supermirrors to obtain depthgraded multilayers with two different neutron scattering length materials (Vidal et al, 1992). Researchers from RIKEN conducted amorphous nickel-phosphorus (Ni-P) plating, diamond cutting and polishing on the substrate surface, and coated supermirrors on the substrate.…”

Section: Introductionmentioning

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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“…From past research, we know that the Ni-C co-sputtering fabricating method can increase the difference in neutron SLD, reduce the size of the Ni crystal grain, and suppress the diffusion between layers compared with Ni/Ti multilayers [14][15][16]. Grimmer et al explained that the occupancy of C atoms in the octahedral interstitial positions of the Ni fcc crystal caused the strengthening of the Ni 200 peak in NiC x /Ti multilayers [17,18].…”

Section: Introductionmentioning

confidence: 99%

“…Wood et al gave the optimal atomic ratio of Ni 86 C 14 and Ni 72 C 28 , which was based on the method of measuring the neutron reflectivity [16]. Vidal et al found that the doping of C atoms in the Ni layer and the inserting of hydrogen atoms in the Ti layer by reactive hydrogen sputtering to prepare Ni-C/TiH multilayers showed a better performance in terms of reflectivity [15]. Zhu et al concluded that the C-doped layer could make the Ni/Ti interfaces smoother by comparing the Ni/Ti multilayers and Ni-C/Ti multilayers through TEM images [21].…”

Section: Introductionmentioning

confidence: 99%

Crystallization and Composition of Ni-C/Ti Multilayer with Varied Ni-C Thickness

Zhang

Liu

et al. 2022

Coatings

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Ni-C/Ti are suitable for the components of neutron supermirrors with high reflectivity because of their excellent optical constant and smoother interfaces compared to Ni/Ti. In this paper, to investigate the mechanism of C doping to the interface, crystallization, and composition of a Ni-C/Ti multilayer with variable Ni-C thickness, four Ni-C/Ti multilayers were prepared by direct current magnetron sputtering, in which the thickness of the Ni-C layers was 1.5 nm, 2.5 nm, 3.5 nm, and 4.5 nm, respectively, and the thickness of the Ti layers was kept at 5 nm. The prepared samples were characterized by XRD, XPS, HRTEM, EDX, and SAED. The XRD and HRTEM results show that Ni-C layers in Ni-C/Ti multilayers translate from amorphous to polycrystal form, with their thickness increasing from 1.5 to 4.5 nm, and the crystallite size in Ni-C layers is equivalent to the layer thickness, respectively. The XPS, SAED, and EDX results illustrate that the enrichment position of C in Ni-C/Ti multilayers evolves from the Ni-C layers to the Ti layers as the respective Ni-C layer thickness increases from 2.5 to 4.5 nm. The enrichment position evolution of C in Ni-C/Ti multilayers could be due to the lower standard Gibbs free energy of TiC (−180.1 KJ/mol) compared with NiTi (−37.3 KJ/mol) and Ni3Ti (−35.9 KJ/mol) at 298K.

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<title>Reflectivity improvements for neutron mirrors and supermirrors</title>

Cited by 15 publications

References 0 publications

<title>Optimization of depth-graded multilayer designs for EUV and x-ray optics</title>

<title>Optimization of depth-graded multilayer designs for EUV and x-ray optics</title>

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

Crystallization and Composition of Ni-C/Ti Multilayer with Varied Ni-C Thickness

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