Design And Preliminary Experiment For Testing The Gravitational Inverse-square Law Based On 32-fold Symmetrical Torsion Balance

Gravity is described by the General Relativity,and electromagnetic,strong,and weak interactions are described by the Standard Model.Physicists have been committed to unify the four fundamental interactions.A lot of theories have been proposed to unify the four fundamental interactions,and predict the gravitational Inverse-Square law will be broken in the short range regime.Based on the previous experiment,the author has completed the improved experiment.In the improved experiment,the electrostatic noise have been further studied.The nearest separation between the pendulum and the attractor is set to 210 μm.The data at different separation are processed by maximum likelihood estimation.The Yukawa force was not found in the experiment,and the result give a stongest bound on α of Yukawa violation at the range of 40-350 μm,and improve the previous bounds about 3 times at the length scaleλ ≈ 70 μm.On the other hand,the result also improve the constraints on the power-law potentials by about a factor of 2 for k = 4 and 5.A 32-fold symmetric scheme is also proposed by the author based on the previous experiment.Compared with the previous experiment,the area and the thickness of the test mass and source mass are increased to enlarge the Yukawa torque about one order of magnitude.In addition,the azimuth symmetry of the attractor is increased from 8-fold to 32-fold,which can further separate the signal frequency and the driving frequency.The new experiment will be a null experiment by using the dual compensation design.The result of the calculation shows that the new scheme can give a new constraints of the Yukawa violation at the range of 40-800 μm,and improve the previous bounds about one order of magnitude at the length scale λ ≈ 300 μm.We have performed the background experiment to verify the feasibility of the new scheme.We have assembled all of the background experimental components,and put them in the vacuum chamber.The typical power spectrum density of the pendulum is closing to the thermal noise limit of the tungsten fiber.The preliminary result of the background experiment shows no disturbance produced by the driving system at the signal frequency.