Nuclear structure from light muonic atoms (Dr. B. Franke) / LWFA-driven hard X-ray sources at LEX and CALA (K. Khrennikov)

Nuclear structure from light muonic atoms (Dr. B. Franke)
Muonic atoms have an increased sensitivity on finite size effects of the nucleus due to the ~200-fold mass of the muon compared to the electron. The CREMA collaboration has measured the Lamb shift in muonic hydrogen and muonic deuterium atoms, as well as in muonic helium-4 and helium-3 ions. These measurements allow to determine charge radii and other nuclear properties with improved precision compared to previously conducted measurements. Contributions to solving the proton radius puzzle as well as the discrepancy in electronic isotope-shift measurements from the collected data will be discussed. A status update of CREMA's ongoing data analysis towards charge radius extractions of the deuteron, helion, and the alpha particle will be given. Current analysis-related topics such as theory issues and possible systematics will be shown, together with an outlook for possible future measurements using bound muonic systems.

LWFA-driven hard X-ray sources at LEX and CALA (K. Khrennikov)
We present data on a various X-ray production schemes from laser-wakefield-driven electron beams. This includes detailed electron beam characterization measurements [1] from various gas target sources, comparing beam properties form different targets. Since stable beams can now be routinely achieved over a wide range of parameters, we show their use for X-ray production by undulator radiation, betatron emission [2] and Thomson scattering [3]. A quantitative phase-contrast tomogram of an insect has been recorded with a 5-keV betatron source with few-micron source size. We show that our method permits accurate reconstruction of electron densities in the insect by comparing our reconstructed images with electron-microscopy images. For Thomson scattering, we demonstrate the onset of the nonlinear scattering regime by the spectral downshift of the emitted radiation due to the transverse excursion of the electron bunch in a colliding pulse with a0=0.9, and the presence of second and third order harmonic emission. We will make a prognosis about the source parameters with the LEX and CALA lasers, show the latest status of the ongoing facility upgrade at Garching and present first electron beam results with the upgraded 300 TW laser.

References:
[1] M. Heigoldt et al, accepted by Phys. Rev. Spec. Top. Accel. Beams (2015)
[2] J. Wenz et al., Nature Communications 6 7568 (2015)
[3] K. Khrennikov et al., Phys. Rev. Lett. 114 195003 (2015)