Instrumental neutron activation analysis of an enriched 28Si single-crystal

D'Agostino, G.; Bergamaschi, L.; Mana, Giovanni; Oddone, Massimo

doi:10.1007/s10967-013-2722-5

Cited by 9 publications

(7 citation statements)

References 16 publications

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“…Through a joint agreement, the Istituto Nazionale di Ricerca Metrologica (INRIM) and the Australian Nuclear Science and Technology Organisation (ANSTO) carried out preliminary tests with samples of natural and 28 Si-enriched materials. The results confirmed the possibility of reaching mass fraction detection limits below 1 × 10 –9 for a large number of elements. − …”

Section: Determination Of the Impuritiessupporting

confidence: 72%

Purity of ²⁸Si-Enriched Silicon Material Used for the Determination of the Avogadro Constant

et al. 2016

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At present, counting atoms in a one-kilogram sphere made of (28)Si-enriched silicon allows the determination of the Avogadro constant with the 2.0 × 10(-8) relative standard uncertainty required for the realization of the definition of the new kilogram. With the exception of carbon, oxygen, boron, nitrogen, and hydrogen, the claimed uncertainty is based on the postulation that the silicon material used to manufacture the sphere was above a particular level of purity. Two samples of the silicon were measured using instrumental neutron activation analysis to collect experimental data to test the purity assumption. The results obtained in two experiments carried out using different research reactor neutron sources are reported. The analysis confirmed that the silicon material was of sufficient purity by quantifying the ultratrace concentration of 12 elements and determining the detection limits of another 54 elements.

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Section: Determination Of the Impuritiessupporting

confidence: 72%

Purity of ²⁸Si-Enriched Silicon Material Used for the Determination of the Avogadro Constant

et al. 2016

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“…INRIM has also developed a method based on INAA giving direct evidence of the crystal purity with respect to a very large number of elements. Test measurements carried out at the TRIGA Mark II reactor at the University of Pavia (with a thermal neutron flux of 6 × 10 12 cm −2 s −1 ) included fifty-nine elements and achieved a detection limit of less than 1 ng g −1 for thirty-five elements [10,11]. Two samples were cut from the AVO28 boule and another purity check is planned in early 2015, using the OPAL reactor of the Australian Nuclear Science and Technology Organisation (with a thermal neutron flux of 20 × 10 13 cm −2 s −1 ).…”

Section: Point Defectsmentioning

confidence: 99%

Improved measurement results for the Avogadro constant using a²⁸Si-enriched crystal

Azuma¹,

et al. 2015

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New results are reported from an ongoing international research effort to accurately determine the Avogadro constant by counting the atoms in an isotopically enriched silicon crystal. The surfaces of two 28 Si-enriched spheres were decontaminated and reworked in order to produce an outer surface without metal contamination and improved sphericity. New measurements were then made on these two reconditioned spheres using improved methods and apparatuses. When combined with other recently refined parameter measurements, the Avogadro constant derived from these new results has a value of N A = 6.022 140 76(12) × 10 23 mol -1 . The X-ray crystal density method has thus achieved the target relative standard uncertainty of 2.0 × 10 -8 necessary for the realization of the definition of the new kilogram.

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“…The N A value measured at PTB coincided with that previously obtained in the Avogadro project within u r = 3 × 10 −8 . Moreover, a measurement of the contributions of extraneous chemical elements in the silicon specimen used for fabrication of the ball AVO28-S8, conducted at INRIM [46], also confirms the confidence of u r = 3 × 10 −8 in the result of the Avogadro project.…”

Section: Measurement Datamentioning

confidence: 53%

On the New Definitions for the SI Base Units. Why the Atomic Kilogram is Preferable

et al. 2015

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The role of the fundamental constants and of measurement data on the Planck and Avogadro constants, the kelvin, and the electrical charge in the planned transition to new definitions of the four SI base units (kilogram, mole, ampere, and kelvin) based on fixed values of these constants is discussed. Keywords: redefinition of the SI base units, fundamental physical constants, dimension of a physical quantity, instability of the international prototype kilogram.There are three main unsolved problems in modern physics: determination of the four known physical interactions, including gravitation; dark energy and dark matter in the contemporary expansion of the universe; and possible variations in the fundamental physical constants, the fine structure constant, gravitation constant, ratio of the proton and electron masses, etc.In physical theories, constants characterize the stability properties of different forms of matter, objects, processes, and so on, and remain invariant under different circumstances, at least in terms of existing measurement uncertainties. Since the fundamental physical constants or combinations of them create natural scales for the basic units of measurements, they are referred to as fundamental. As science develops, physical theories are replaced by more general theories with their own sets of constants, with new relationships among them. Thus, we can only discuss a set of constants corresponding to the modern situation in the physical sciences, rather than some absolute set of fundamental physical constants [1].At present, the standard model of strong and electroweak interactions is consistent with most of the available experimental data. A fairly well tested (mainly in the solar system) theory of gravitation (Einstein's general theory) also exists. The standard cosmological model (the spatially flat Fridman model with a cosmological constant, ΛCDM) and its many modifications and generalizations play an important role in cosmology with its rapidly developing observational basis and theoretical interpretations. In each of these theories, there are problems with the corresponding set of constants [1,2], and with the further development of physics the existing set of fundamental physical constants (FPC) will probably change, but it is not currently known when this will happen.The systems of units of physical quantities are a part of the necessary toolkit of science. Like any toolkit, they must correspond to the current state of development of science. The redefinition of the Systeme Internationale (SI) base units now being prepared can be regarded as an answer to this need [3]. The planned reform of the SI relies on a proposal to define the base units by setting exact values of the corresponding FPC in accordance with the principle used in 1983 for redefining the meter.Since 2005, it has been proposed for the SI reform that, in particular, the values of the Planck h, Boltzmann k, and Avogadro N A constants and of the electronic charge e be fixed with zero uncertainty, and that this should serve...

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Instrumental neutron activation analysis of an enriched 28Si single-crystal

Cited by 9 publications

References 16 publications

Purity of ²⁸Si-Enriched Silicon Material Used for the Determination of the Avogadro Constant

Purity of ²⁸Si-Enriched Silicon Material Used for the Determination of the Avogadro Constant

Improved measurement results for the Avogadro constant using a²⁸Si-enriched crystal

On the New Definitions for the SI Base Units. Why the Atomic Kilogram is Preferable

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Instrumental neutron activation analysis of an enriched 28Si single-crystal

Cited by 9 publications

References 16 publications

Purity of 28Si-Enriched Silicon Material Used for the Determination of the Avogadro Constant

Purity of 28Si-Enriched Silicon Material Used for the Determination of the Avogadro Constant

Improved measurement results for the Avogadro constant using a28Si-enriched crystal

On the New Definitions for the SI Base Units. Why the Atomic Kilogram is Preferable

Contact Info

Product

Resources

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Purity of ²⁸Si-Enriched Silicon Material Used for the Determination of the Avogadro Constant

Purity of ²⁸Si-Enriched Silicon Material Used for the Determination of the Avogadro Constant

Improved measurement results for the Avogadro constant using a²⁸Si-enriched crystal