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Journal of Research of the National Institute of Standards and Technology

Optical diffraction in close proximity to plane apertures, part 2, comparison of half-plane diffraction theories

Optical diffraction in close proximity to plane apertures, part 2, comparison of half-plane diffraction theories Klaus D. Mielenz The accuracy and physical significance of the classical Rayleigh-Sommerfeld and Kirchhoff diffraction integrals are assessed in the context of Sommerfeld’s rigorous theory of half-plane diffraction and Maxwell’s equations. It is shown that the Rayleigh-Sommerfeld integrals are in […]

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Journal of Research of the National Institute of Standards and Technology

Accuracy of nanoscale pitch standards fabricated by laser-focused atomic deposition

Accuracy of nanoscale pitch standards fabricated by laser-focused atomic deposition Jabez J. McClelland The pitch accuracy of a grating formed by laser-focused atomic deposition is evaluated from the point of view of fabricating nanoscale pitch standard artifacts. The average pitch obtained by the process, nominally half the laser wavelength, is simply traceable with small uncertainty […]

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Journal of Research of the National Institute of Standards and Technology

Concrete Mixing Methods and Concrete Mixers: State of the Art

Concrete Mixing Methods and Concrete Mixers: State of the Art Dr. Chiara F. Ferraris As for all materials, the performance of concrete is determined by its microstructure. Its microstructure is determined by its composition, its curing conditions, and also by the mixing method and mixer conditions used to process the concrete. This paper gives an […]

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Journal of Research of the National Institute of Standards and Technology

For state-of-the-art superconductors, NIST investigates the mechanical behavior of RABiTS – General Developments – rolling-aligned biaxially textured substrates

For state-of-the-art superconductors, NIST investigates the mechanical behavior of RABiTS – General Developments – rolling-aligned biaxially textured substrates – Brief Article One of the major challenges facing the development of an economical, practical, high-temperature superconductor has been the extremely weak mechanical behavior of Y-Ba-Cu-O coated onto rolling-aligned biaxially textured substrates (RABiTS). The RABiTS process is […]

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Journal of Research of the National Institute of Standards and Technology

The remarkable metrological history of radiocarbon dating [II]

The remarkable metrological history of radiocarbon dating [II] Lloyd A. Currie This article traces the metrological history of radiocarbon, from the initial breakthrough devised by Libby, to minor (evolutionary) and major (revolutionary) advances that have brought [.sup.14]C measurement from a crude, bulk [8 g carbon] dating tool, to a refined probe for dating tiny amounts […]

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Journal of Research of the National Institute of Standards and Technology

New video on Charpy impact testing – General Developments

New video on Charpy impact testing – General Developments – Brief Article To help customers of the Charpy impact-testing program, NIST is now distributing a video, “How Tough is Steel.” The 20 mm video begins with a background of the Charpy test, then covers the details of the verification program run by NIST, and finally […]

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Journal of Research of the National Institute of Standards and Technology

Novel Combinatorial Methods For Inorganic Thin Films

Novel Combinatorial Methods For Inorganic Thin Films – Brief Article Over the past decade, combinatorial chemistry, which involves high throughput synthesis and analysis of a multivariable “library” containing a large number of miniaturized samples, has revolutionized the drug discovery process in the pharmaceuticals industry. Recently, materials scientists have been applying combinatorial principles to the discovery […]

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Journal of Research of the National Institute of Standards and Technology

Three improvements in reduction and computation of elliptic integrals

Three improvements in reduction and computation of elliptic integrals B. C. Carlson Three improvements in reduction and computation of elliptic integrals are made, 1. Reduction formulas, used to express many elliptic integrals in terms of a few standard integrals, are simplified by modifying the definition of intermediate “basic integrals.” 2. A faster than quadratically convergent […]

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Journal of Research of the National Institute of Standards and Technology

Nist’s Cryptographic Module Validation Program Adds Web Access For Security Policies – National Institute of Standards and Technology

Nist’s Cryptographic Module Validation Program Adds Web Access For Security Policies – National Institute of Standards and Technology – Brief Article In April 2001, NIST updated its Cryptographic Module Validation Module (CMVP) web pages to allow convenient user access to all of the Federal Information Processing Standard (FIPS) 140-1 validated cryptographic module security policies. Making […]

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Journal of Research of the National Institute of Standards and Technology

Measurement of neutron decay parameters—the abBA experiment

Measurement of neutron decay parameters—the abBA experiment W.S. Wilburn We are developing an experiment to measure the correlations a, A, and B, and the Fierz interference term b in neutron decay, with a precision of approximately [10.sup.-4]. The experiment uses an electromagnetic spectrometer in combination with two large-area segmented silicon detectors to detect the proton […]