“…The use of two electron beam systems, one operated as electron target, at different electron energies or cooling by stochastic cooling are options to operate at a continuous detuning without compromising the quality of the cooled beam [38]. Alternatively, transverse electron targets which use electrons not confined by a longitudinal magnetic field and cross the ion beam with very low energy have also been considered [39]. They have the advantage of a well defined interaction point in the longitudinal degree of freedom.…”