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In this paper the Bayesian analysis is applied to assign a probability density to the value of a quantity having a definite sign. This analysis is logically consistent with the results, positive or negative, of repeated measurements. Results are used to estimate the atom density shift in a caesium fountain clock. The comparison with the classical… (More)

High-accuracy dimensional measurements by laser interferometers require corrections because of diffraction, which makes the effective fringe-period different from the wavelength of a plane (or spherical) wave λ<sub>0</sub>. By using a combined X-ray and optical interferometer as a tool to investigate diffraction across a laser beam, we observed wavelength… (More)

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… (More)

- E Massa, G Mana, U Kuetgens
- 2009

To base the kilogram definition on the atomic mass of the 28 Si atom, the present relative uncertainty of the 28 Si lattice parameter must lowered to 3 × 10 −9. To achieve this goal, a new experimental apparatus capable of a centimetre measurement-baseline has been made at the INRIM. The comparison between the determinations of the lattice parameter of… (More)

Caesium fountain frequency-standards realize the second in the International System of Units with a relative uncertainty approaching 10 −16. Among the main contributions to the accuracy budget, cold collisions play an important role because of the atomic density shift of the reference atomic transition. This paper describes an application of the Bayesian… (More)

- A Apolloni, G Mana, C Palmisano, G Zosi
- 2008

In this paper we investigate x-ray and γ-ray propagation in crystals having a constant strain gradient and flat or cylindrical surfaces. When a displacement field is present, we solve the Takagi-Taupin equations either by the Riemann-Green method or by a numerical method. We apply the results to study the operation of a double-crystal Laue-Laue… (More)

- M Gai, F Bertinetto, M Bisi, E Canuto, D Carollo, S Cesare +4 others
- 2007

ESA is supporting an industrial study aimed at preliminary assessment of some critical aspects of the GAIA mission implementation: hereafter, our study approach is presented. The Fizeau interferometer of GAIA features a strict correlation between the conventional telescope and interferometer concepts and problems. The wide angle measurement concept is based… (More)