Calculate the flux of the vector field \(\mathbf{E}(x, y, z)=\langle 0,0, xangle\) through the part of the ellipsoid
\[
4 x^{2}+9 y^{2}+z^{2}=36
\]
where \(z \geq 3, x \geq 0, y \geq 0\). Hint: Use the parametrization
\[
\Phi(r, \theta)=\left(3 r \cos \theta, 2 r \sin \theta, 6 \sqrt{1-r^{2}}ight)
\]