@article{LiStockSchlamminger, author = {Li, Shisong and Stock, Michael and Schlamminger, Stephan}, title = {A new magnet design for future Kibble balances}, series = {Metrologia}, volume = {55}, journal = {Metrologia}, number = {3}, publisher = {IOP PUBLISHING}, doi = {10.1088/1681-7575/aab2ea}, pages = {319 -- 325}, abstract = {We propose a new permanent magnet system for Kibble balance experiments, which combines advantages of the magnet designs invented by the National Physical Laboratory (NPL) and by the Bureau International des Poids et Mesures (BIPM). The goal of the proposed magnet system is to minimize the coil-current effect and to optimize the shielding at the same time. In the proposed design, a permanent magnet system with two gaps, each housing a coil, is employed to minimize the coil current effect, by reducing the linear coil-current dependence reported for the single air gap design by at least one order of magnitude. Both air gaps of the magnet are completely surrounded by high-permeability material, and hence the coils are shielded from outside magnetic fields and no magnetic field leaks outside of the magnet system. An example of the new magnet system is given and the analysis shows that the magnetic field in the air gap can be optimized to meet the requirement to be used in Kibble balances.}, language = {en} } @article{RothleitnerSchlamminger, author = {Rothleitner, Christian and Schlamminger, Stephan}, title = {Invited Review Article: Measurements of the Newtonian constant of gravitation, G}, series = {Review of Scientific Instruments}, volume = {88}, journal = {Review of Scientific Instruments}, number = {11}, publisher = {AIP Publishing}, doi = {10.1063/1.4994619}, abstract = {By many accounts, the Newtonian constant of gravitation G is the fundamental constant that is most difficult to measure accurately. Over the past three decades, more than a dozen precision measurements of this constant have been performed. However, the scatter of the data points is much larger than the uncertainties assigned to each individual measurement, yielding a Birge ratio of about five. Today, G is known with a relative standard uncertainty of 4.7 x 10(-5), which is several orders of magnitudes greater than the relative uncertainties of other fundamental constants. In this article, various methods to measure G are discussed. Alarge array of different instruments ranging from the simple torsion balance to the sophisticated atom interferometer can be used to determine G. Some instruments, such as the torsion balance can be used in several different ways. In this article, the advantages and disadvantages of different instruments as well as different methods are discussed. A narrative arc from the historical beginnings of the different methods to their modern implementation is given. Finally, the article ends with a brief overview of the current state of the art and an outlook.}, language = {en} }