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) were measured using a photon-counting single-shot pixelated Silicon-based detector, 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. 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.