Experimental Tests Of Newtonian Inverse-Square-law At Submillimeter Range

Unifying the fundamental interactions in nature is a wonderful desire for physicists. As we know,gravitational interaction is weaker so much than the other fundamental forces that people suppose spacial extra-dimensions be existent for establishing unification models.An inevitable predictions coursed by extra-dimension is that Newtonian Gravitational Inverse Square Law(ISL) will violate at short distance scale.Up to now,all experimental results were only obtained the upper constrains on deviations of ISL.The experimental test of the ISL is equal to verify the theory of gravity itself,and any evidence of ISL broken will bring great influence on development of the whole physics.Author of this thesis started the experimental test of the ISL in 2003.Based on the comprehensive researches on the related fields and a few years elaborate preparation,the first low frequency dual-modulation experiment of precise torsion balance was completed at distance down to 176μm in 2006.Experimental results disclosed that the upper limit on non-Newtonian forces wasλ≤66μm when |α|=1 and the uniform energy M~*≥2.8TeV/c~2. In 2009,we have fulfilled the improved experiment,the gap between the test and source masses was reduced and a high frequency dual-modulation is used to improve the resolution of the torsion pendulum.Furthermore more credible method of data analysis method is used.The new result gave an more stringent limit ofλ≤37μm when |α|=1 and the uniform energy M~*≥3.7TeV/c~2,with an improvement of 1～2 order compared with the result of our previous experiment,and became the new constraints in the range of 12μm～220μm!This work was partially supported by the National Natural Science Foundation of China(10075021,10121503) and the National Basic Research Program of China (2003CB716300).