Free-fall gravitational acceleration measurement using a pneumatically controlled catch-and-release-system in a semi-rotating vacuum chamber

• Autorzy: Mokobodi T. , Greeff P. , Kruger O. , Theron N. J.

Identyfikatory

DOI

10.24425/mms.2018.124875

• Języki publikacji: EN

Abstrakty

EN

Knowledge of gravitational acceleration in metrology is required for traceable force and pressure calibrations, furthermore the redefinition of the SI base unit of kilogram requires absolute accomplishment of the gravitational acceleration. A direct free-fall gravimeter is developed using pneumatic grippers for test mass handling and a semi-rotary actuator for repositioning, i.e. automated re-launching. The catch and release system is powered by compressed air. This eliminates electric interferences around the test mass. A simplified method of signal capturing and processing is used on the designed gravimeter. A digital frequency trigger is implemented in the post processing algorithms to ensure that the signals are analysed from the identical effective height. The experimental results measured the site gravitational acceleration of 9.786043 ms ^-2 with a statistical uncertainty of ± 29 μs^-2.

Słowa kluczowe

EN

direct free fall; gravitational acceleration; interferometer

• Wydawca: Komitet Metrologii i Aparatury Naukowej PAN
• Czasopismo: Metrology and Measurement Systems
• Rocznik: 2018
• Tom: Vol. 25, nr 4
• Strony: 689--699
• Opis fizyczny: Bibliogr. 23 poz., rys., tab., wykr., wzory

Twórcy

autor

Mokobodi T.

• University of Pretoria, Private bag X20, Hatfield, Pretoria, South Africa, 0028

autor

Greeff P.

• National Metrology Institute of South Africa, CSIR, Meiring Naude Rd, Brummeria, Pretoria, 0040

autor

Kruger O.

• National Metrology Institute of South Africa, CSIR, Meiring Naude Rd, Brummeria, Pretoria, 0040

autor

Theron N. J.

• University of Pretoria, Private bag X20, Hatfield, Pretoria, South Africa, 0028

Bibliografia

• [1] Nabighian, M.N., Ander, M.E., Grauch, V.J., Hansen, R.O., LeFehr, T.R., Li, Y., Pearson, W.C., Pierce, J.W., Phillips, J.D., Ruder, M.E. (2005). Historical development of the gravity method in exploration. Geophysics, 70(6), 63ND-89ND.
• [2] Darling, D. (2006). Gravity’s Arc: The story of gravity from Aristotle to Einstein and beyond. New Jersey: John Wiley and Sons.
• [3] Stock, M. (2011). The watt balance: determination of the Planck constant and redifination of the kilogram. Philosophical transactions of the royal society, 369(2011), 3936-3953.
• [4] Sanchez, C.A., Wood, M.B., Green, R.G., Liard, J.O., Inglis, D. (2014). A determination of Planck’s constant using NRC watt balance. Metrologia, 51(2014), S5-S14.
• [5] Krynski, J. (2012). Gravimetry for geodesy and geodynamics – brief historical review. Reports on Geodesy, 92(1), 1-16.
• [6] Gillot, P., Cheng, B., Merlet, S., Pereira Dos Santos, F. (2009). The LNE-SYRTE cold atom gravimeter. PSL Research University. Paris: PSL Research University, 1-3.
• [7] AbdElazem, S., Al-Basheer. W. (2015). Measuring the acceleration due to gravity using IR transciver. European Journal of Physics, 36, 45017.
• [8] Abellan-Garcia, F.J., Garcia-Gamuz, J.A., Valerdi-Perez, R.P., Ibanez-Mengual, J.A. (2012). Gravity acceleration measurement using a soundcard. European Journal of Physics, 33, 1271-1276.
• [9] Faller, J.E., Marson, I. (1988). Ballistic Methods of Measuring g - the Direct Free-Fall and Symmetrical Rise and Fall Methods Compared. Metrologia, 25, 49-55.
• [10] Svitlov, S., Maslyk, P., Rothleitner, C., Hu, H., Wang, L.J. (2010). Comparison of three digital fringe signal processing methods in ballistic free-fall absolute gravimeter. Metrologia, 47(6), 677-689.
• [11] Rothleitner, C. (2008). Ultra-High Precision, Absolute Earth Gravity Measurements. Dissertation. Max Plank Research Group.
• [12] Hanada. H., Tsubokawa, T., Takano, S., Tsuruta, S. (1987). New design of absolute gravimeter for continous observations. Review of Scientific Instruments, 58(4), 669-673.
• [13] D’Agostin, G., Desogus, S., Germak, A., Origlia, C., Quagliotti, D., Berrino, G., Corrado, G., d’Errico, V., Ricciardi, G. (2008). The new IMGC-02 transportable absolute gravimeter: measurement apparatus and applications in geophysics and volcanology. Annals of Geophysics, 51(1), 39-49.
• [14] Cook, A.H. (1965). The absolute determination of accelaration due to gravity. Metrologia, 1(3), 84-113.
• [15] Bell, G.A., Gibbings, D.L.H., Patterson, J.B. (1973). An absolute determination of the gravitational acceleration at Sydney, Australia. Metrologia, 9, 47-61.
• [16] Niebauer, T.M., Hollander, W.J., Faller, J.E. (1992). Absolute Gravity Inline Measuring Apparatus Incorporating Improved Operating Features. Micro-g Solution, 45(US005351122A), 1-18.
• [17] Hammond, J.A. (1970). A laser-interferometer system for the absolute determination of the accelaration of gravity. PhD Thesis. Colarad: University of Colorado.
• [18] Torge, W. (1989). Gravimetry. New York: Walter de Gruyter.
• [19] Hariharan, P. (2007). Basics of Interferometry. 2nd ed. Sydney: Elsevier.
• [20] Svitlov, S., Rothleitner, C., Wang, L. (2012). Accuracy assessment of the two-sample zero-crossing detection in a sinusoidal signal. Metrologia, 49, 413-424.
• [21] Ilango, S., Soundararajan, V. (2007). Introduction to Hydraulics and Pneumatics. India: Prentice-Hall of India Private Limited.
• [22] Ludger, T. (2003). Precise definition of the effective measurements height of the free-fall absolute gravimeter. Metrologia, 40, 62-65.
• [23] Rothleitner, C., Francis, O. (2010). On the influence of the rotation of a corner cube reflector in absolute gravimetry. Metrologia, 47, 567-574.

Uwagi

EN

1. The authors would like to acknowledge NMISA, which provided the sponsorship for this project, and the department of Mechanical and Aeronautical engineering of the University of Pretoria.

PL

2. Opracowanie rekordu w ramach umowy 509/P-DUN/2018 ze środków MNiSW przeznaczonych na działalność upowszechniającą naukę (2018).