长方体\(ABCD-A_{1}B_{1}C_{1}D_{1}\)的\(8\)个顶点都在球\(O\)的表面上，\(E\)为\(AB\)的中点，\(CE=3\)，\(\cos ∠ACE= \dfrac {5 \sqrt {3}}{9}\)，且四边形\(ABB_{1}A_{1}\)为正方形，则球\(O\)的直经为\((\)　　\()\)