Assmann, R., Bingham, R., Bohl, T., Bracco, C., Buttenschön, B., Butterworth, A., et al. (2014). Proton-driven plasma wakefield acceleration: a path to the future of high-energy particle physics. Plasma Physics and Controlled Fusion, 56: 084013. doi:10.1088/0741-3335/56/8/084013.