Würzburg 2018 – scientific programme
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AKBP: Arbeitskreis Beschleunigerphysik
AKBP 6: Synchrotron Radiation Sources (SR and FEL)
AKBP 6.8: Talk
Tuesday, March 20, 2018, 18:15–18:30, NW-Bau - HS5
Inverse Thomson Scattering from a MeV Laser Plasma Accelerator and Plasma Mirror — •Andrea Hannasch1,2, Rafal Zgadzaj1,2, Alejandro Laso-Garcia1, Ulrich Schramm1, Arie Irman1, and Michael Downer1,2 — 1Helmholtz-Zentrum Dresden-Rossendorf, Institut fur Strahlenphysik, 01328 Dresden, Germany — 2University of Texas at Austin, Austin, Texas 78012, USA
We convert a MeV laser-plasma accelerator (LPA) driven by the DRACO Laser at HZDR into a compact, femtosecond-pulsed, tunable gamma-ray source by inserting a 25 um-thick transparent low Z Kapton foil ~mm after the accelerator exit. The foil acts as a plasma mirror (PM) that retro-reflects spent drive laser pulses (1.55 eV) with field strength a0 ~ 1 back onto trailing electrons (peak Lorentz factor tunable from 500 - 1000). Compton backscatter generated approximately 1e8 gamma-ray photons with few mrad divergence, and estimated peak brilliance 1e21 photons/s/mm2/mrad2/0.1% bandwidth. Scaling of the generated signal with PM position indicates that the nonlinear Thomson scattering regime is accessible with a PM, and further scaling of thickness and material indicates that bremsstrahlung generated by MeV electrons within the PM is negligible. Gamma-ray photon energy, inferred from the measured electron energy distribution on each shot and measured by a stack calorimeter, peaked at ~ 1 MeV, accessing a range otherwise available with comparable brilliance only from large-scale linac-based high-intensity gamma-ray sources.