Speaker
Ms
Andrea Hannasch
(University of Texas at Austin)
Description
We convert a GeV laser-plasma accelerator (LPA) driven by the Texas Petawatt Laser into a compact, femtosecond-pulsed, tunable gamma-ray source by inserting a 12 to 100µm-thick transparent low Z (glass or plastic) foil ~3 cm after the accelerator exit. The foil acts as a plasma mirror (PM) that retro-reflects spent drive laser pulses (1.17 eV) with field strength a0 ~ 0.3 back onto trailing electrons (peak Lorentz factor tunable from 1000 to 4400). The spectrum of the retro-reflected pulse differs only slightly from the incident spectrum, since the LPA operates well below the pump-depletion limit. Compton backscatter generated approximately 1e8 gamma-ray photons with sub-mrad divergence, and estimated peak brilliance 1e21 photons/s/mm2/mrad2/0.1% bandwidth. Scaling of the generated signal with PM position, thickness and material indicates that bremsstrahlung generated by GeV electrons within the PM is negligible. Gamma-ray photon energy, inferred from the measured electron energy distribution on each shot, peaked from 5 to 85 MeV, spanning a range otherwise available with comparable brilliance only from large-scale GeV-linac-based high-intensity gamma-ray sources that support nuclear photonic research and applications.
Primary authors
Dr
Aaron Bernstein
(University of Texas at Austin)
Mr
Joseph M. Shaw
(University of Texas at Austin)
Prof.
Michael Downer
(University of Texas at Austin)
Dr
Rafal Zgadzaj
(University of Texas at Austin)
Co-authors
Ms
Andrea Hannasch
(University of Texas at Austin)
Dr
Hai-En Tsai
(University of Texas at Austin)
Mr
James Welch
(University of Texas at Austin)
Mr
Maxwell LaBerge
(University of Texas at Austin)
Dr
Neil Fazel
(University of Texas at Austin)
Ms
Weichman Kathleen
(University of Texas at Austin)
Mr
Yen-Yu Chang
(University of Texas at Austin)
