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Mise en pratique for the definition of the kelvin

Traceable thermometry. Mise en pratique for the definition of the kelvin updated version, Comité consultatif de thermométrie (CCT), 2011 http://www.bipm.org/en/publications/mep_kelvin/ Scope:

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Mise en pratique for the definition of the kelvin

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  1. Traceable thermometry • Mise en pratique for the definition of the kelvin • updated version, Comitéconsultatif de thermométrie (CCT), 2011 • http://www.bipm.org/en/publications/mep_kelvin/ • Scope: • “This document provides the information needed to perform a practical measurement of temperature in accord with the International System of Units (SI).” • The mise en pratique serves as a reference for: • the text of the ITS-90 and PLTS-2000 • a Technical Annex of material deemed essential to realisation of the ITS-90 or PLTS-2000, but not included in the scale definitions themselves • descriptions of primary thermometers for direct measurement of thermodynamic temperature • assessments of the uncertainty of the ITS-90, PLTS-2000, and measurements made by primary thermometry

  2. Traceable thermometry • Mise en pratique for the definition of the kelvin • updated version, Comitéconsultatif de thermométrie (CCT), 2011 • http://www.bipm.org/en/publications/mep_kelvin/ • fundamental change in the practice of traceable temperature measurement • direct measurements by primary thermometers • more flexible approach → user no longer will be tied to the ITS • removes the short-term need for establishing a new unified international temperature scale from the lowest to the highest temperatures

  3. Temperature scales time

  4. Temperature scales ITS-90 ↔ PLTS-2000 ? • Schuster G. et al., • Temperature, its Measurement and Control in Science and Industry, • Vol. 6, (Edited by J.F. Schooley), New York, American Institute of Physics, • pp. 97-100 (1992) • Fogle W.E. et al., ibid. pp. 85-90 PTB-2006 3He vapour pressure scale PTB-2006PTB-2006 ≡ ITS-90 2 K ≤ T ≤ 3.2 K PTB-2006 ≡ PLTS-2000 0.65 K ≤ T ≤ 1 K Engert et al., Metrologia, 44, 40 (2007) Engert et al., Metrologia, 44, 40 (2007)

  5. Temperature scales pm/ MPa = S ai(T2000 / K)i (i= -3···9) Trange: 0.9 mK to 1 K p range: 2.9 MPa to 4 MPafixed points p3He / MPaT2000 / mK Minimum 2.93113 315.24 A 3.43407 2.444 A-B 3.43609 1.896 Néel 3.43934 0.902

  6. PLTS-2000 - Realization Uncertainty for the realization of the PLTS-2000 in comparison to an approximation using a pressure calibration of the MPT adjusted to the 3He melting pressure minimum, calibrated superconductive reference point samples (W, Mo) and an interpolating resistance thermometer for the region around the minimum. Red lines show the uncertainty of the PLTS-2000 in terms of thermodynamic temperature.

  7. PLTS-2000 - Dissemination Resistance thermometers Superconductive reference point samples MFFTs, CSNTs

  8. PLTS-2000 - Dissemination = D 2 U 4 k TR f B s T 2 4 k TM = 0 S ( f , T ) = S ( f , T ) b b æ ö 2 æ ö 2a æ ö f æ ö f ç ÷ ç ÷ ç ÷ + R 1 ç ÷ + 1 ç ÷ ç ÷ ç ÷ f ç ÷ è ø f è ø è ø c è ø c • Practical noise thermometry →Nyquist relation • dc-SQUID based detection of thermal magnetic flux noise generated by noise currents in a metallic temperature sensor • Measurement of power spectral density (PSD): S(f,T) CurrentSensing Noise Thermometer (CSNT) 1st order low-pass spectrum with fall-off frequencyfc = R/(2πL). If R = const(T): SF(f = 0 Hz, T) ~ T Magnetic Field Fluctuation Thermometer (MFFT) “Low-pass-like” spectral shape depends on geometry. If R = const(T): SF(f = 0 Hz, T) ~ T spectral shape is independent of T

  9. PLTS-2000 - Dissemination MFFT-1 Noise Thermometer Magnicon GmbH

  10. PLTS-2000 - Dissemination Uncertainty of T measurement with a calibrated MFFT Goal → temperature measurement with relative expanded uncertainty Urel (TMFFT) ~ 1% (k = 2, 95%) within ~ 60 s calibration of the MFFT at Tcal calibration temperature fssample rate Ns number of samples, Mavgnumber of averages for calibration measurement Navgnumber of averages for temperature measurement Df= fhigh - flow frequency range used for T determination Nf number of frequency bins in Df

  11. PLTS-2000 - Dissemination s T = 0 S ( f , T ) b æ ö 2a æ ö f ç ÷ ç ÷ + 1 ç ÷ N S ( f , T ) ç ÷ T f f è ø å è ø np c = T cal np N S ( f , T ) f f cal S ( f , T ) = T T cal S ( f , T ) cal ò ( ) = 2 2 u ( T ) ( T - T ) p ( T | y ) dT ò = B B T p T | y dT N T S ( f , T ) 1 T B f å T inp = - T ( 1 ) cal inp M N S ( f , T ) f avg f cal 2 u ( T ) 2 u ( T ) 1 1 inp = + + cal 2 2 × × T T N N M N cal avg f avg f inp Parametric model: fit of PSD at Tcal→ Θcal={s0, a, b, fc} fit of measured PSD with Θcal →Tp, u(Tp) Non-parametric model: Tnp→ may be affected by bias Improved non-parametric model: Bayesian approach: coherent uncertainty estimates using MCMC techniques probability density functions V(t) → FFT → PSD → averaging Wübbeler et al., Meas. Sci. Technol. 23, 125004 (2012), ibid. 2013

  12. PLTS-2000 - Dissemination (a) Tcal= 850 mK Mavg= 2400 Navg= 10 (b) Tcal = 850 mK Mavg= 10 Navg= 2400 Temperature estimates and uncertainties obtained by the Bayesian treatment TB, by the parametric approach TP and by the two non-parametric approaches Tnp and Tinp. The error bars indicate 95 % credible intervals for the Bayesian treatment and 95 % coverage intervals for Tp, Tnp and Tinp Wübbeler et al., Meas. Sci. Technol., to appear 2013

  13. PLTS-2000 - Dissemination Urel (TMFFT) ≤ 1%

  14. PLTS-2000 - Dissemination • Calibration certificate • parameters for SQUID setup • parameters for DAQ box • PSD at calibration temperature • calibration parameters • Tmin for U ≤ 1%

  15. Ultra low-temperature 195Pt-NMR On the way to a ultra low-temperature scale T ≤ 1 mK

  16. Ultra low-temperature 195Pt-NMR Experimental set-up : Cu-Pt nuclear cooling stages r (cm) Bz (T) z (cm) Reference-point device Pt-NMR #1 Pt-NMR #2 Pt-NMR #3 Heat switch Cu nuclear cooling stage Heat switch Pt nuclear cooling stage

  17. Ultra low-temperature 195Pt-NMR Pulsed Pt-NMR thermometry is based on measurements of nuclear magnetisation of a high-purity bulk samples. The temperature fields and result from the thermodynamic process of thermometry and are compared to the recorded free induction decay (FID). Ziele 2012

  18. Ultra low-temperature 195Pt-NMR r r T ( x , t ) T ( x , t ) e N • nuclear demagnetization cooling and magnetic thermometry = two aspects of one and the same thermodynamic process • , →solution of thermodynamic field equations • investigation of properties of Pt → susceptometer

  19. PLTS-2000 - Background data PTB- and UF-Scale TNTUF - TPTB = 54 µK (6 %) TBTUF - TPTB = 78 µK (4 %) TATUF - TPTB = 95 µK (4 %) PTB- and NIST-Scale T : 30 mK < T < 750 mK, DT/T < 0.3 % p : D p = 110 Pa (attheminimum)

  20. InK - Project • European Metrology Research Programme (EMRP) • “Implementing the new Kelvin” - InK project 2012 – 2015 → T-T90, T-T2000 • 14 national metrological institutes, 3 res. Grants, NPL – coordinator • http://projects.npl.co.uk/ink/ • Work package 4 - “Primary thermometry for low temperatures” • development of primary thermometers → T-T2000 • CSNT, CBT, MFFT • to resolve the long standing discrepancy between the background data on which PLTS-2000 is based

  21. Conclusions - Outlook • International Temperature Scales are essential for maintenance • and dissemination of the Kelvin with low uncertainties • T ≥ 1mK • Dissemination of ITS-90 and PLTS-2000 down to 1 mK • sc. reference points, resistance thermometers • practical noise thermometers → MFFT, on-chip CSNT • new calibration service, U(TMFFT)≤ 1% • Discrepancies in the background data of PLTS-2000 below 10 mK • EMRP-project→ “InK” • T ≤ 1mK • ultra-low temperature scale - part of a follow-up project ? • choice of scale carrier - investigation of material properties • development and evaluation of primary thermometers • comparison measurements between different thermometers/laboratories • development of transfer standards    

  22. Acknowledgments • PTB J. Beyer, D. Drung, M. Schmidt, Th. Schurig • D. Heyer, B. Fellmuth, J. Fischer • P. Strehlow, E. Bork • G. Wübbeler, F. Schmähling, C. Elster • Magnicon GmbH H.-J. Barthelmess S. AliValiollahi • University of Heidelberg, Kirchhoff Institute ofPhysics Ch. Enss et al. • Royal Holloway University of London • J. Saunders et al.

  23. Estimates of the differences between thermodynamic temperature and the ITS-90 http://www.bipm.org/utils/en/pdf/Estimates_Differences_T-T90_2010.pdf

  24. Relative deviation of Tnoise from T2000/90 for different noise thermometers. Linearity of Tnoise in terms of T2000/90 for different noise thermometers..

  25. Ultra low-temperature 195Pt-NMR Both Nuclear Demagnetisation Cooling and Magnetic Thermometryare two aspects of one and the same thermodynamic process. It arises from solution of proper field equations for boundary and initial values that can be controlled in the demagnetisation experiment. Thermodynamic field equations are derived from the Boltzmann equation for the phase density of metal electrons and the Master equation for the probability density to find a nuclei with z-spin. • energy density of metal electrons • energy density of nuclear spins • heat flux • magnetisation • caloric and thermal equations of state Both the thermodynamic temperature and the spin temperature result from the numerical solution of field equations for a given demagnetisation process .

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