Elements of prime order in Tate-Shafarevich groups of abelian varieties over

For each prime p, we show that there exist geometrically simple abelian varieties A over with. Specifically, for any prime, let be an optimal quotient of with a rational point P of order p, and let. Then the number of positive integers with is, where is the dual of the dth quadratic twist of B. We prove this more generally for abelian varieties of-type with a p-isogeny satisfying a mild technical condition. In the special case of elliptic curves, we give stronger results, including many examples where for an explicit positive proportion of integers d.