Cabadag, J. P. C., Pausch, R., Schöbel, S., Bussmann, M., Chang, Y.-Y., Corde, S., et al. (2021). Gas-dynamic density downramp injection in a beam-driven plasma wakefield accelerator. Physical Review Research, 3(4): L042005. doi:10.1103/PhysRevResearch.3.L042005.