If the volume of a tetrahedron with coterminous edges \(\vec{a},\vec{b}\) and \(\vec{c}\), (where \(\vec{a}\) is a unit vector) is \(13\) cubic units and the angle between \(\vec{a}\) and \(\vec{b}\times \vec{c}\) is \(\frac{\pi }{3}\), then \(|\vec{b}\times \vec{c}|\) is