Test of the electron hose instability in the E157 experiment

The E157 experiment is designed to demonstrate high gradient plasma wake field acceleration over a significant length. It has been suggested that the electron hose instability of the drive beam will degrade the performance of this experiment because the hosing tail electrons will not fully sample the highest acceleration field. In this paper a parasitic experiment designed to test the extent of the hosing instability is described. In particular, we discuss how the initial beam conditions are determined so that the extent to which any transverse perturbations grow due to hosing can be determined.