Final report of CCAUV.V-K3: key comparison in the field of acceleration on the complex charge sensitivity

Abstract

This is the final report for CIPM key comparison CCAUV.V-K3 in the area of 'vibration' (quantity of acceleration). The aim of this comparison was to measure the voltage sensitivity of one accelerometer standard set with primary means at 27 frequencies from 0.1 Hz to 40 Hz. Fourteen Metrology Institutes from five RMOs have participated in the comparison with National Institute of Metrology, P.R. China as pilot lab and Laboratoire National de Métrologie et d'Essais and National Metrology Institute of South Africa as co-pilot labs. One quartz-flexure servo accelerometer of single-ended type and a signal conditioner was circulated among the participants. All but one of the participating laboratories provided their calibration results, which were mostly consistent within their declared expanded uncertainties for magnitude results. Only two participants failed to contribute to the KCRV values calculated for five frequencies. For phase shift, three participants could not contribute to the calculation of the KCRV values in a total of sixteen frequencies. This first low-frequency vibration key comparison revealed the current calibration capabilities of the fourteen participants of five RMOs. Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCAUV, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Traceable calibration of a broadband seismometer down to 5 mHz

“…The other uncertainty sources, such as the temperature dependence of the sensitivity, voltage measurement uncertainty, and laser wavelength uncertainty, are expected to be sufficiently small or independent of the frequency or excitation amplitude. Therefore, their contributions do not exceed the previous estimation in [9], which was up to 0.04% standard uncertainty. This becomes dominant above 0.1 Hz, where the tilt-coupling contribution and its correction uncertainty is small as shown in figures A1 and A2.…”

“…Above 10 Hz, the problems can arise due to the vibration characteristics of the mechanical components, as investigated in [4,15]. Although the calibration above 10 Hz is almost established for the smallsize accelerometers [9,16], the large size and weight of the seismometers cause the problem of the mechanical resonance around 100 Hz. However, these are beyond the primary scope of this paper.…”

“…Well-known uncertainty sources other than the tilt-coupling are shown in [9] for the calibration at >0.1 Hz. Among them, the background noise contribution can be larger in the seismometer calibration due to the small excitation amplitude, âr , at low frequencies.…”

“…Some correction methods were discussed in [8], which included the static tilt measurement by an autocollimator or inertial sensor and the dynamic fitting method, and they were compared down to 0.1 Hz. The National Metrology Institute of Japan (NMIJ) also implemented the correction based on the inertial tilt measurements to the calibration down to 0.1 Hz [9]. The camera-based estimation and correction of the tilt were also investigated down to 0.04 Hz [10].…”

Precise sinusoidal signal extraction from noisy waveform in vibration calibration

“…The estiation accuracy is essential for the calibration uncertainty. The requirement for the primary calibration is about 0.1 % and 0.1 • for the amplitude and phase, respectively [6,7]. In these studies, large vibration that was nearly 10 m/s 2 was applied.…”