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CCEM. Comité Consultatif d’ Électricité et Magnétisme Report of the President to the 22 nd CGPM. Ernst O. Göbel PTB Braunschweig and Berlin, Germany. CCEM. Structure of the CCEM E. O. Göbel, PTB, President T. J. Witt, BIPM, Executive Secretary

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Ccem

CCEM

Comité Consultatif

d’ Électricité et Magnétisme

Report of the President to the 22nd CGPM

Ernst O. Göbel

PTB Braunschweig and Berlin, Germany


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Structure of the CCEM

E. O. Göbel, PTB, President

T. J. Witt, BIPM, Executive Secretary

22 members + director of the BIPM, 4 observers

Four working groups:

• Working Group on Electrical Methods to Monitor the Stability of

the Kilogram / Chairman: I. Robinson, NPL

• Working Group on AC Measurements of the Quantized Hall Resistance

Chairman: E. Braun, PTB (until Sept. 2002); J. Melcher, PTB (since Sept. 2002)

• Working Group on Key Comparisons (until Sept. 2002);

Working Group on Low Frequencey Quantities (since Sept. 2002)

Chairman: H. Bachmair, PTB

• Working Group on Radiofrequency Quantities

Chairman: L. Erard, BNM (until Sept. 2002), J. P. Randa, NIST (since Sept. 2002)


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Meetings:

CCEMSept. 2000, BIPM

Sept. 2002, BIPM

WG: Key ComparisonsSept. 2000, BIPM

now: WG: Low Frequency June 2001, BIPM

QuantitiesSept. 2002, BIPM

WG: Radiofrequency QuantitiesSept. 2000, BIPMJune 2001, BIPM

Sept. 2002, BIPM

WG: Monitoring the StabilityMay 2000, Sydney

of the KilogramJune 2002, Ottawa

July 2003, Paris

WG: AC Measurements of the QHEMay 2000, Sidney

Sept. 2000, BIPM

June 2002, Ottawa

Sept. 2002, BIPM


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STATUS OF LEAST-SQUARES

ADJUSTMENT

OF FUNDAMENTAL CONSTANTS


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Fundamental Constants:


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KJ-90 ; RK-90

• KJ-90 and RK-90 remain comfortably coherent with the most recent (1998) CODATA values (however the 2002 KJ value might differ slightly when the new value for the Avogadro constant is included)

• The relative standard uncertainty assigned to RK has been reduced by a factor of 2 to 1 x 10-7 (CIPM approved in 2000); i.e. the representation of the Ohm using the QHE and RK-90 agrees with the SI-Ohm within 1x10-7 with a reproducibility which is much better (~10-9)


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QHE - Key Comparisons


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Revised Technical Guidelines for Reliable Measurements of the Quantized Hall Resistance

F. Delahaye, BIPM, and B. Jeckelmann, METAS

Metrologia, to be published

www.bipm.org


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ELECTRICAL METHODS TO

MONITOR THE STABILITY OF

THE INTERNATIONAL PROTOTYPEOF THE KILOGRAM

Required for Monitoring the Stability of the Kilogram:

s < 10-8 !


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Watt balance (Planck constant)

NPL in operation after considerable reconstruction. Target uncertainty < 3 parts in 108 in 2004

NIST in test operation after complete reconstruction.

Operation in vacuum, electromagnetically shielded environment, new support system, incorporation of programmable Josephson system. Daily runs show typical standard deviation of about 0.06 W/W. Target uncertainty  1 in 108


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Watt balance (contd.)

METAS in test operation (100 g mass);

different construction;

A new magnet will be mounted by

the end of 2003.

BNM design phase completed;

under construction.

BIPMdesign phase.


Mass levitation flux quantum

CCEM

Mass levitation (flux quantum)

NMIJ/AIST:achieved relative uncertainty: 1x10-6,

basic studies (precision trajectory

measurement, trapped magnetic flux etc.)

VNIIM/ MIKES:Nb films on monocrystalline sapphire films;

superconducting levitation frame weighing

100 g


Avogadro co operation

CCEM

Avogadro co-operation

Determination of the Avogadro constant using

Silicon Single Crystals

BIPM PTB IMGC NMIJ CSIRO

NIST NPL IRMM

Achieved rel. uncertainty:

1.7 x 10-7, however:


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NA = 6.022 135 53 (103) x 1023/mol

Comparison of the Avogadro constant


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  • SET:

  • Single Electron

  • Tunneling Devices

  • for Metrological

  • Applications

  • current

  • capacitance

  • temperature

  • photons on

  • demand


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COUNT

Counting Electrons One by One:Measurement of Very Small Electrical Currents

2000 - 2001 - 2002

A research project supported by the European Commissionunder Framework Programme 5(Contract No. G6RD-CT 1999-00046)


Count

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COUNT

  • Instrumentation for precise generation

  • of small currents based on SET pumps;

  • Aim: 1x10-6 for current of a few pA

  • Instrumentation for measurement of small

  • currents based on SET counter;

  • Aim: 1x10-5 for a current of a few pA

Achieved: 3.2 pA with  = 4x 10-6 (type A)


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N

U

C

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Capacitance Standard

Capacitance standard,based on the quantization ofelectrical charge

Example with numbers:

C = 1 pF, N = 108 Þ U »16 V

NIST

(1992)

Relevant for metrology if the relative uncertainty becomes better than 10 -7 !

„Measuring the electron´s charge and the fine-structure constant by counting the

electrons on a capacitor“,Williams et al., J. Res. Nat. Inst. Stand. Technol.97, 299 (1992)


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Capacitance Standard (contd.)

  • NIST 1996:This experiment is feasiblewith a relative uncertainty of 10 - 8 NIST 1999: First measurement of a cryo-cap´s capacitanceby using the SET method„A capacitance standard based on counting electrons“, M. W. Keller et al., Science 285, 1706 (1999)

  • NIST 2003:Reproducibility (s)= 1  10 -7

  • Total uncertainty (C)  1 10 -6

  • Ccryo-cap 10 pF compared to a calc. capacitor

  • 7 junction SET pump (error rate  10-8)

  • SET electrometer (null detector; sensitivity 10-3 · e)


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Alternatives:

A)Si based SETTs (NIST)

smaller charge offset; parallel integration

B) Single Cooper Pair Tunneling (SCPT) Devices(NIST, PTB)

C)Single Electron Transport by Surface Acoustic

Waves (SETSAW) (NPL, Univ. Cambridge, PTB)

B) and C): higher operation frequency


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0

-3

-6

8.5

9.0

9.5

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AC Measurement of the QHE

BIPM, NRC, METAS, PTB, NML, IEN, NIST

Specially designed samples and multiple series connection

  1 x 10-7


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1V Programmable Standard

NIST

  • Programmable from

  • +1.1 V to -1.1 V

  • 1 s settling time

  • Output Step Height =

  • 2 to 4 mA


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Josephson Arbitrary Waveform

Synthesizer (JAWS) (supported by the EC)

JAWS homepage

Participants

www.jaws-project.nl


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JAWS

AC voltage standard for arbitrary waves based on

Josephson Arbitrary Waveform Synthesiser

Objectives:f = 1 Hz - 10 kHz

U0 = 10 mV

 < 10-4


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CCEM Key Comparison

and Calibration and Measurement Capabilities

102 CIPM and RMO Key Comparisons (total 516) recorded in KCDB

17 completed (total 103)

9094 CMC entries (total 15830)


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indeed is very active!

Thanks for your attention!


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