CCEM

Comité Consultatif d’ Électricité et Magnétisme

Report of the President to the 22nd CGPM

Ernst O. GöbelPTB Braunschweig and Berlin, Germany

CCEMStructure of the CCEM

E. O. Göbel, PTB, PresidentT. 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)

CCEMMeetings:CCEM Sept. 2000, BIPM

Sept. 2002, BIPM

WG: Key Comparisons Sept. 2000, BIPMnow: WG: Low Frequency June 2001, BIPMQuantities Sept. 2002, BIPM

WG: Radiofrequency Quantities Sept. 2000, BIPMJune 2001, BIPMSept. 2002, BIPM

WG: Monitoring the Stability May 2000, Sydney of the Kilogram June 2002, Ottawa

July 2003, Paris

WG: AC Measurements of the QHE May 2000, SidneySept. 2000, BIPMJune 2002, OttawaSept. 2002, BIPM

CCEM

STATUS OF LEAST-SQUARES ADJUSTMENT

OF FUNDAMENTAL CONSTANTS

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Fundamental Constants:

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• 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)

KJ-90 ; RK-90

QHE - Key ComparisonsQHE - 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 TOMONITOR THE STABILITY OF

THE INTERNATIONAL PROTOTYPEOF THE KILOGRAM

Required for Monitoring the Stability of the Kilogram:

< 10-8 !

CCEM

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

Watt balance (Planck constant)

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.

BIPM design phase.

CCEMWatt balance (contd.)

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

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Avogadro co-operation

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Determination of the Avogadro constant usingSilicon Single Crystals

BIPM PTB IMGC NMIJ CSIRO

NIST NPL IRMM Achieved rel. uncertainty:1.7 x 10-7, however:

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6,022132

6,022134

6,022136

6,022138

6,022140

6,022142

6,022144

CO

DA

TA

-98

WG

AC

-20

03

NA

/(102

3 /mo

l)

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

Comparison of the Avogadro constant

SET:Single ElectronTunneling Devicesfor MetrologicalApplications

• current• capacitance • temperature• photons on demand

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COUNTCounting Electrons One by One:

Measurement of Very Small Electrical Currents 2000 - 2001 - 2002

A research project supported by the European Commission under Framework Programme 5

(Contract No. G6RD-CT 1999-00046)

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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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Capacitance standard,based on the quantization ofelectrical charge

Example with numbers:

C = 1 pF, N = 108 U 16 V

CUNe

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

N

C

U

„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)

Capacitance Standard

NIST(1992)

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• 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 ()= 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)

CCEM Capacitance Standard (contd.)

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

B) and C): higher operation frequency

Alternatives:

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P BP BTTAC-QHE (AC-QHE (samplesample designdesign))

8.5 9.0 9.5

-6

-3

0

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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CCEM1V 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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JAWS homepage

www.jaws-project.nl

Participants

Josephson Arbitrary WaveformSynthesizer (JAWS) (supported by the EC)

JAWSCCEM

AC voltage standard for arbitrary waves based onJosephson Arbitrary Waveform Synthesiser

Objectives: f = 1 Hz - 10 kHzU0 = 10 mV < 10-4

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

17 completed (total 103)

9094 CMC entries (total 15830)

CCEM Key Comparison

and Calibration and Measurement Capabilities

CCEMindeed is very active!

Thanks for your attention!