Test of the equivalence principle for ordinary matter falling toward dark matter

We tested the equivalence principle (EP) for Be, Cu, and Al falling toward the galactic center, and found {Δ}a(Be,Cu)=-(0.1 ±{}5.8)×{}10^-12 cm/s² and {Δ}a(Be,Al)=(3.6±{}6.9)×{}10^-12 cm/s². As dark matter is thought to account for (25--30)% of our galacticentric acceleration, the EP parameters for Be/Cu, or Be/Al, falling toward dark matter, are {η}(Be,Cu)=(0.0±{}1.2)×{}10^-3 and {η}(Be,Al)=(0.7±{}1.4)×{}10^-3 (1{σ} errors). This limits any EP-violating component of our acceleration toward dark matter and provides laboratory evidence that gravitation is the only significant long-range interaction between dark and ordinary matter.