High Resolution Energy-Angle Correlation Measurement of Hard X Rays from Laser-Thomson Backscattering

Thomson backscattering of intense laser pulses from relativistic electrons not only allows for the generation of bright x-ray pulses but also for the investigation of the complex particle dynamics at the interaction point. For this purpose a complete spectral characterization of a Thomson source powered by a compact linear electron accelerator is performed with unprecedented angular and energy resolution. A rigorous statistical analysis comparing experimental data to 3D simulations enables, e.g., the extraction of the angular distribution of electrons with 1.5% accuracy and, in total, provides predictive capability for the future high brightness hard x-ray source PHOENIX (photon electron collider for narrow bandwidth intense x rays) and potential gamma-ray sources.

Figure 1

Schematic of the interaction for a head-on geometry ($\phi =\pi$) including kinematic effects ($\Delta \phi$) (a) as well as detector size ($\Delta {\Omega }_{\mathrm{Det}}$). The detector is placed on the electron beam axis ($\theta =0$) (b).

Figure 2

Experimental setup of the Thomson backscattering source at the ELBE accelerator.

Figure 3

Full data set (QE corrected) combined with CLARA simulation results and Eq. (1) (dotted black line) (a) and exemplary raw data spectra at observation angles $\theta =1.15$ and 11.6 mrad to illustrate changes in the shape of the distribution (b).

Figure 4

Analysis of the statistical moments, mean $\mu$, standard deviation $\sigma$, and skewness. The shaded area represents a $1\sigma$-confidence interval from the CLARA simulation. The horizontal uncertainty is 0.6 mrad.