Abstract：A differential accelerometer comprising of two rotating masses made of the same material is proposed for drop tower-based free-fall testing of the spin–spin force between the rotating mass and the Earth. The measurement is performed by placing the two concentric masses of very different momenta in a vacuum drop capsule which is falling freely in the Earth's gravitational field. A nonzero output of the differential accelerometer is an indication of possible violation of new equivalence principle (NEP). We present the conceptual design of a modified free-fall NEP experiment which can be performed at the Beijing drop tower. Design and evaluation of the differential accelerometer with a hybrid electrostatic/magnetic suspension system are presented to accommodate for operation on ground and drop-tower tests. Details specific to the measurement uncertainty are discussed to yield an NEP test accuracy of $7.2\times10^{-9}$.
Nobili A M, Shao M, Pegna R, Zvattini G, Turyshev S G, Lucchesi D M, De Michele A, Doravari, S, Comandi G L, Saravanan T R et al 2012 Class. Quantum Grav.29 184011
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Iafolla V, Lucchesi D M, Nozzoli S, Ravenna M, Santoli F, Shapiro I I, Lorenzini E C, Cosmo M L, Bombardelli C, Ashenberg J et al 2011 Adv. Space Res.47 1225
2017, Vol. 34 
