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Towards Uniformity of DC Voltage Metrology within SIM

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  • 1. Towards Uniformity of DCVoltage Metrology within SIM Yi-hua Tang Quantum Electrical Metrology Division National Institute of Standards and Technology Gaithersburg, MD 20899 VIII SEMETRO
  • 2. OutlineDC voltage metrology status within SIMJVS Comparison MAP Indirect comparison Direct comparisonSummaryFuture perspective VIII SEMETRO
  • 3. Lab / Country No. of JVSNIST / USA 4 (20)NRC / Canada 1CENAM / Mexico 1INMETRO / Brazil 1INTI / Argentina 1 VIII SEMETRO
  • 4. Principle of JVS V = nf / KJ-90f: frequencyKJ-90 = 2e/h = 483 597.9 GHz/V Josephson constantn: integer BIPM.EM-K10.a JVS at 1.018V BIPM.EM-K10.b JVS at 10 V BIPM.EM-K11.b Zener at 10 V SIM.EM.BIPM-K11.a Zener at 1.018 V SIM.EM.BIPM-K11.b Zener at 10 V SIM.EM.BIPM-K10.b JVS at 10V VIII SEMETRO
  • 5. MAP Example 1: NIST-BIPM JVS comparison at 10 V 3 system comparison: BIPM NIST-Gaithersburg NIST-Boulder Oct. 1998 – Jan. 1999 BIPM.EM-K11.b Pressure corrections applied. VIII SEMETRO
  • 6. Results of BIPM.EM-K11.b d (μV) uc (μV) (k = 1)NIST(G) - BIPM 0.26 0.14NIST(B) - BIPM 0.22 0.17NIST(G) – NIST(B) 0.04 0.13 Uncertainty: 1 - 2 parts in 108 VIII SEMETRO
  • 7. INMETRO JVS system Established in 1998 VIII SEMETRO
  • 8. INMETRO-NIST JVS Comparison at 1.018V Sept. to Oct. 1999 Protocol: MAP SIM.EM.BIPM-K11.a Z6 Z3 INMETRO 92.6 97.6 NIST Linear (INMETRO) 92.5 Offset from 1.018V (μV) 97.5 Offset from 1.018V (μV) 92.4 97.4 INMETRO 92.3 NIST 97.3 Linear (INMETRO) 92.2 97.2 y = -0.00565391x + 295.00550325 y = 0.01066458x - 280.46730707 92.1 97.1 9/3 9/8 9/13 9/18 9/23 9/28 10/3 10/8 10/13 9/3 9/8 9/13 9/18 9/23 9/28 10/3 10/8 10/13 Date Date Z5 INMETRO Z7 126.6 114.5 INMETRO NIST NIST Linear (INMETRO) Linear (INMETRO) 126.4 114.4 Offset from 1.018V (μV)Offset from 1.018V (μV) 126.2 114.3 126.0 114.2 125.8 114.1 y = -0.02007355x + 827.94375914 y = 0.00224443x + 35.74730979 125.6 114.0 9/3 9/8 9/13 9/18 9/23 9/28 10/3 10/8 10/13 9/3 9/8 9/13 9/18 9/23 9/28 10/3 10/8 10/13 Date Date VIII SEMETRO
  • 9. ∑ [(Vi (predict) − Vi (NIST )]Δ(INMETRO − NIST ) = 13 13 Z3 Z5 Z6 Z7INMETRO - NIST 0.023 0.052 0.001 0.013 Mean( INMETRO − NIST ) = 0.022 μV INMETRO − NIST 2 uc = 2 (uINMETRO ) + (u NIST ) + ( 3.18 u ) + (u INMETRO, NIST ) 2 2 2 A A 2 B B Source Uncertainty (μV) Pooled Type A of INMETRO, uAINMETRO 0.003 Pooled Type A of NIST, uANIST 0.006 Standard deviation of mean of four 0.011 Zener differences uBINMETRO -NIST Type B uncertainty from INMETRO and NIST JVS 0.016 systems, uBINMETRO, NIST Expanded uncertainty (k = 2) 0.049 VIII SEMETRO
  • 10. Question: Is MAP good enough for JVS comparison?Answer: NoWhy?1. JVS uncertainty: few parts in 1010 MAP uncertainty: few parts in 1082. Uncertainty using MAP limited by Zener characteristics Environmental effects • Pressure • Temperature • Relative humidity Zener intrinsic noise Shipping impact VIII SEMETRO
  • 11. Question: How can we improve the situation?Answer: Develop a transportable JVS 8.5” Net weight: 50 lb Gross weight: 120 lb VIII SEMETRO
  • 12. NIST-CENAM SIM.EM.BIPM-K11.bNIST CJVS in CEMETRO, March 2006 VIII SEMETRO
  • 13. Yi-hua Tang Enrique Navarrete Dionisio Hernández David Avilés VIII SEMETRO
  • 14. Results of NIST-CENAM SIM.EM.BIPM-K11.bNo pressure correction needed. VIII SEMETRO
  • 15. To establish a link between CENAM and BIPM DCENAM-BIPM = (dNIST-BIPM + dCENAM-NIST) UCENAM-BIPM = (UNIST-BIPM2 + UCENAM-NIST 2)1/2 d (μV) uc (μV) CENAM - NIST -0.035 0.043 NIST - BIPM 0.26 0.28 CENAM - BIPM 0.23 0.28 VIII SEMETRO
  • 16. VIII SEMETRO
  • 17. Question: Is indirect JVS comparison good enough?Answer: NoWhy?JVS uncertainty: few parts in 1010Indirect JVS comparison uncertainty: few parts in 109Uncertainty limited by Zener noise Environmental effects • Pressure • Temperature • Relative humidity Zener intrinsic noise Shipping impact VIII SEMETRO
  • 18. Question: How can we improve the situation?Answer: Do not use Zener as transfer standards. Make direct JVS comparison.Protocol: BIPM JVS comparison Option a; BIPM JVS comparison Option b; Alternative protocols VIII SEMETRO
  • 19. An alternative protocolStep 1 Step 2Step 3 Step 4 VIII SEMETRO
  • 20. NIST-NRC SIM.EM.BIPM-K10.b NIST CJVS at NRC August 2007Barry Wood of NRC VIII SEMETRO
  • 21. VIII SEMETRO
  • 22. Link between NIST and BIPM via NRC VIII SEMETRO
  • 23. NIST-BIPM JVS comparison BIPM.EM-K10.b BIPM protocol Option B 11 9 7 5 3 #1 to #5U (NIST) - U (BIPM) /nV #6 to #8 1 #9 to #10 #11 to #15 #16 to #25 -1 0 5 10 15 20 25 30 35 40 #26 to #30 #31 -3 #32 to #37 -5 -7 -9 -11 Meas. number VIII SEMETRO
  • 24. Histogram of the JVS comparison BIPM protocol Option B VIII SEMETRO
  • 25. NIST-BIPM JVS comparison BIPM.EM-K10.b BIPM protocol Option A 12 10 8 6 4U (NIST) - U (BIPM) / nV 2 0 0 5 10 15 20 -2 -4 -6 -8 -10 #1 to #11 Measurements #12 to #22 VIII SEMETRO
  • 26. U (NIST) – U (BIPM) / nV Option B Option A Measured by NIST Measured by BIPMDifference (nV) -0.074 -1.53Type A (nV) 0.68 0.75Type B (nV) 0.93 0.77Combined uncertainty (nV) 1.15 1.07 VIII SEMETRO
  • 27. Direct link between NIST and BIPM VIII SEMETRO
  • 28. BIPM JVS in NIST March 2009 VIII SEMETRO
  • 29. Yi-hua Tang Stephane Solve Regis Chayramy VIII SEMETRO
  • 30. Automatic JVS direct comparisonModel of NIST protocolVd = Va1 – Va2 = (N1 f1 – N2 f2) / KJ-90Vd - Vm = Vo + mt + Vn + δδ = Vd – Vm – Vo – mt – Vn VIII SEMETRO
  • 31. Automatic JVS direct comparison VIII SEMETRO
  • 32. Example: automatic comparison nominal voltage: 9.997 V217 points in 14 h. U (NIST) – U (BIPM) / nV ua / nV 0.02 0.24 VIII SEMETRO
  • 33. BIPM.EM-K10.a SummaryBIPM.EM-K10.bBIPM.EM-K11.bSIM.EM.BIPM-K11.bSIM.EM.BIPM-K10.bNot listed in BIPM KCDB VIII SEMETRO
  • 34. Comparison of various protocols MAP CJVS JVS vs. JVS PJVS vs. PJVS (Indirect) (Indirect) (Direct) (Future)Voltage range Up to 10 V Up to 10 V Up to 10 V Up to 10 V Uncertainty 2 x 10-8 2 x 10-9 1 - 7 x 10-10 parts x 10-11Limiting factor Zener Zener Null detector Null detector (1/f noise)Time needed Weeks Days Hours Hours Expense Low High High Potentially low VIII SEMETRO
  • 35. Future perspective Coming soon: new 10 V PJVSExpected uncertainty: few parts in 1011 at 10 V Detection of small system error is possible VIII SEMETRO