  The main purpose of this paper is to show the nonexistence of tight Euclidean
9-designs on 2 concentric spheres in $\mathbb R^n$ if $n\geq 3.$ This in turn
implies the nonexistence of minimum cubature formulas of degree 9 (in the sense
of Cools and Schmid) for any spherically symmetric integrals in $\mathbb R^n$
if $n\geq 3.$
