New constraints on composition-dependent interactions with ranges down to 1 cm

This paper reports the first results from a new torsion-balance that uses a 3 ton Uranium source mass which slowly rotates around the pendulum. The highly symmetric pendulum consists of a Be tray with machined positions for four test masses (two Cu test bodies, and two Pb-Cu test bodies) giving a composition dipole suspended from a thin W torsion fiber. The Pb counter-balanced source is shaped to minimize gravity gradients. Our instrument has sensitivity for forces with Yukawa ranges down to λ=1 cm, and achieves optimal sensitivity for λ≥10 cm. The author sets improved limits on interactions coupled to N - Z (isospin) for ranges between λ=1 cm and λ=1000 km. The results indicate no such new interaction. For interactions coupled to baryon number our result improves limits in the short range region as well as for λ=10 - 200 km. (TEC). 9 refs., 2 figs