Figure 4: Energy loss measurements.
From: Demonstration of a positron beam-driven hollow channel plasma wakefield accelerator
(a) A histogram of the beam energy loss for all 315 shots corrected for incoming energy jitter (see the Methods for details). The plasma channel is present when the laser is on (red). When the laser is off (blue) the beam is propagating through neutral lithium vapour. We fit the laser-on data to a gaussian (black dashed curve) with mean energy loss 18.9 MeV and width 3.2 MeV. (b) A comparison of the average beam energy spectra for laser on and laser off shots. The s.d. error bars represent the statistical uncertainty in the upper and lower regions of the spectrum due to averaging (see Supplementary Fig. 4 for details). The error has been multiplied by a factor of five so that it is visible in the plot.
