X-ray Emission from Electron Betatron Motion in a Laser-Plasma Accelerator.

Single-shot x-ray spectra from electron bunches produced by a laser-plasma wakefield accelerator (LPA) [1, 2] were measured using a photon-counting single-shot pixelated Silicon-based detector [3], providing for the first time single-shot direct spectra without assumptions required by filter based techniques. In addition, the electron bunch source size was measured by imaging a wire target, demonstrating few micron source size and stability. X-rays are generated when trapped electrons oscillate in the focusing field of the wake trailing the driver laser pulse [4, 5, 6, 7, 8]. In addition to improving understanding of bunch emittance and wake structure, this provides a broadband, synchronized femtosecond source of keV x-rays. Electron bunch spectra and divergence were measured simultaneously and preliminary analysis shows correlation between x-ray and electron spectra. Bremsstrahlung background was managed using shielding and magnetic diversion. [ABSTRACT FROM AUTHOR]