Mass standard for the french watt balance experiment - pure iridium -

Transcription

1 INSTITUT NATIONAL DE METROLOGIE Workshop Secondary and Reference Mass Standard Bucharest March Mass standard for the french watt balance experiment - pure iridium - Z. Silvestri, P. Pinot, T. Rivet and L. Grouet

2 Comparison of the selected materials for watt balance Density (kg.m -3 ) v magnetic susceptibility Ir, Pt-Ir : Johnson-Matthey AuPtAgCu : Px group Hardness (Hv5) v ( 10-5 ) Pt-10%Ir Ir ,9 AuPtAgCu ,8 Pt BMG ,7 Some dislocations No laboratory able to forge the metal Very good hardness Good density Development of a polishing procedure characterization by optical roughness meter & X reflectometer Cleaning procedure BIPM, solvents, UV/Ozone, thermaldesorption, Storage conditions air, vacuum, inert media,

3 Means of the LNE-INM/Cnam Means Optical Roughness Meter Information expected. Scattered light mapping. Roughness parameters X-Ray Reflectometer *. Roughness parameters Mirage Effect TDS Mass Comparators * LP/Cnam. Adsorbability. Physisorbed elements. Mass evolution

4 Optical Roughness Meter Laser sources 633 nm (incidence 46 ) & 543 nm (incidence 70 ) Spatial frequency 3, to 1, µm -1 & 10-3 to 2, µm -1 Analyzed surface ~ 1,5 mm² Resolution 0,1 nm Scattered light mapping Determination of 2 statistical parameters using PSD rms roughness & correlation length To do in 2008! measurements around the specular new 405 nm possibility of moving source (-90 to 0 ) study of cylindrical surface??? d 1 2π 1 d 4 λ cosθ W S k Power Spectral Density (PSD) Fourier Tranf. of the autocorrélation function (ARS : Angle Resolved Scattering) Échantillon Sample Laser He-Ne q 0 Détecteur Detection q Si Photodector 16 elements + NI USB Module

5 TDS : Experimental device ThermalDesorption Mass Spectrometry (TDS) load lock chamber & analysis chamber high vacuum ~10-6 Pa high quadripolar mass spectrometer (SEM & Faraday) sample diameter 39 to 54 mm heating holder up to 1200 C To do in 2008! modification of the load lock chamber Mass spectrometer adsorbed molecules sample T Mass spectrum amu pression pressure pics desorption désorption T 0 Mass spectrometer time temps température temperature T = T 0 + b t IR lamps Heating holder Mass transporter Analisys chamber Sas d introduction Load lock chamber

6 ln(s²) Study of the polishing / Roughness Surface characterization of different materials diamond paste polishing (1 µm for the last step) Material Ref. d (nm) Pt-Ir Alacrite XSH Ir Rms roughness C(1) 2,6 C(2) 2,6 D(1) 3,5 D(2) 4,1 F(1).V1 4,1 F(1).V2 2,0 F(2) 2,0 Spatial frequency band : 0,001 to 0,017 µm Power Spectral Density Pt-Ir C(1) Pt-Ir C(2) Ir F(1).V1 Ir F(1).V k² (nm -2 ) Ir F(2) Ir Bande F(1).V1 (1st polishing) F(1).V2 (2 nd polishing) F(1).V2

7 Pure Ir : Thermal desoportion gravimetric method 1. Gravimetric study on transfering a large surface Ir artefact between air-vacuum : a. after polishing and BIPM cleaning b. under vacuum at 10-6 Pa during 3 days c. 3 thermal desorptions (TDS) at 600 C during 2 hours with airing between each TDS! 2. During thermal desorption surface analysis of the contamination Area of this 100 g artefact Ir ~ 241 cm² ( 16 area of 100 g cylindrical mass) 7 3 cm Mass comparator 100 g 5 cm Iridium artefact Mettler-Toledo AT106 TDS device

8 Gravimetric study : first results Mass comparisons in air (20 C) BIPM cleaning vacuum [1] vacuum [2] TDS 1 TDS 2 airing 20 d TDS 3 airing 1 m (-33 ± 3) µg (-0,15 ± 0,02) µg.cm -2 In air : mass evolution after TDS1 (-240 ± 3) µg (-1,55 ± 0,02) µg.cm -2 1 hour (-101 ± 3) µg (-0,60 ± 0,02) µg.cm -2 (-55 ± 3) µg (-0,20 ± 0,02) µg.cm -2 (+41 ± 3) µg (+0,2 ± 0,02) µg.cm -2 (+69 ± 3) µg (+0,30 ± 0,02) µg.cm -2 Values after mass stabilization

9 Study of the contamination [1] Intensity (A) Intensity (A) TDS 1 / 1 month after BIPM cleaning H 2 O, CO 2, SO 2, ethanol, ether, methanol, C x H y, others C x H y O z amu > 45 & not identified TDS 2 / 4 days after TDS 1 and airing H 2 O, CO 2, methanol, C x H y, others C x H y O z amu > 45 & not not identified TDS 3 / 12 days after TDS 2 and airing H 2 O, C x H y, C x H y O z & not identified 3.5E-08 TDS 1 1.4E-09 TDS 1 TDS 2 TDS 3 TDS 2 1.2E E-08 TDS 3 1.0E E E E E E E E E E E amu 0.0E amu Differential mass spectrums

10 Study of the contamination[2] amu Elements TDS2 <> TDS1 TDS3 <> TDS1 12 C+ 32% -100% 13 CH+ -82% -100% 14 N+, CH2+ -90% -93% 15 CH3+ -71% -90% 17 OH+ -64% -57% 18 H2O+ -68% -55% 26 C2H2+ -87% -100% 27 C2H3+ -90% -100% 28 N2+, CO+ -100% -100% 29 C2H5+, CHO+ -84% -98% 30 NO+, C2H6+ -78% -45% 31 CH2OH+ -66% -100% 32 O2+,CH3OH+ -76% -100% 39 C3H3+ -89% -85% 40 Ar+ -84% -92% 41 C2H3N+ -90% -94% 42 CH2N2+ -81% -94% 43 C2H3O+ -79% -92% 44 C3H8+, CO2+ -77% -80% 45 C2H5O+ -66% -91% 46 NO2+, C2H5OH+ -61% -100% 48 SO+ -61% -100% 50 C4H % -100% 54 C4H % -100% 55 C3H5N+ -90% -96% 56 C4H8+ -89% -100% 57 C3H7N+ -91% -95% 59 C3H7O+ -100% -100% 60 C3H8O+ -85% -100% 69 C4H7N+ -90% -100% 73 C4H11N+ -89% -100% 74 C4H10O+ -100% -100% Evolution of the total pressure during the thermal desorption

11 And Others Ir studies to carry out! storage in vacuum or in inert media (argon, nitrogen, ) comparisons with Pt-Ir (to do complemantary studies) Studies on PtAuAgCu study of the roughness study of the cleaning procedure (mainly thermal desorption) study of the storage conditions 734 Euramet Project (Study of materials for the realization of mass standards) project completed final report detailled final report written by the coordinator Patrick Pinot

12 Conclusions Thank You!