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Towards Uniformity of DC Voltage Metrology within SIM

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Towards Uniformity of DC Voltage Metrology within SIM

  1. 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. 2. OutlineDC voltage metrology status within SIMJVS Comparison MAP Indirect comparison Direct comparisonSummaryFuture perspective VIII SEMETRO
  3. 3. Lab / Country No. of JVSNIST / USA 4 (20)NRC / Canada 1CENAM / Mexico 1INMETRO / Brazil 1INTI / Argentina 1 VIII SEMETRO
  4. 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. 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. 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. 7. INMETRO JVS system Established in 1998 VIII SEMETRO
  8. 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. 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. 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. 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. 12. NIST-CENAM SIM.EM.BIPM-K11.bNIST CJVS in CEMETRO, March 2006 VIII SEMETRO
  13. 13. Yi-hua Tang Enrique Navarrete Dionisio Hernández David Avilés VIII SEMETRO
  14. 14. Results of NIST-CENAM SIM.EM.BIPM-K11.bNo pressure correction needed. VIII SEMETRO
  15. 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. 16. VIII SEMETRO
  17. 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. 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. 19. An alternative protocolStep 1 Step 2Step 3 Step 4 VIII SEMETRO
  20. 20. NIST-NRC SIM.EM.BIPM-K10.b NIST CJVS at NRC August 2007Barry Wood of NRC VIII SEMETRO
  21. 21. VIII SEMETRO
  22. 22. Link between NIST and BIPM via NRC VIII SEMETRO
  23. 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. 24. Histogram of the JVS comparison BIPM protocol Option B VIII SEMETRO
  25. 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. 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. 27. Direct link between NIST and BIPM VIII SEMETRO
  28. 28. BIPM JVS in NIST March 2009 VIII SEMETRO
  29. 29. Yi-hua Tang Stephane Solve Regis Chayramy VIII SEMETRO
  30. 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. 31. Automatic JVS direct comparison VIII SEMETRO
  32. 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. 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. 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. 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

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