E-semigroups over closed convex cones

We initiate a study of E-semigroups over convex cones. We prove a structure theorem for E-semigroups which leave the algebra of compact operators invariant. Then we study in detail the CCR flows, E${}_0$semigroups constructed from isometric representations, by describing their units and gauge groups. We exhibit an uncountable family of $2-$parameter CCR flows, containing mutually non-cocycle-conjugate E${}_0$-$semigroups.