Ulrich Bundles on certain Grassmann Bundles Over Curves

Let $E$ be a slope-semistable vector bundle on smooth projective curve $C$. Assume, $ π: G= Gr_{C}(r, E) \to C$ denote the relative Grassmannian of rank $r$ quotients of $E$. We prove that for every very ample polarization $L= O_{G}(1) \otimes π^{*} A$ the polarized variety $(G,L)$ possess an Ulrich