R. A. Marsh

Precision linac and laser technologies for nuclear photonics gamma-ray sourcesa)

Tunable, high precision gamma-ray sources are under development to enable nuclear photonics, an emerging field of research. This paper focuses on the technological and theoretical challenges related to precision Compton scattering gamma-ray sources. In this scheme, incident laser photons are scattered and Doppler upshifted by a high brightness electron beam to generate tunable and highly collimated gamma-ray pulses. The electron and laser beam parameters can be optimized to achieve the spectral brightness and narrow bandwidth required by nuclear photonics applications. A description of the design of the next generation precision gamma-ray source currently under construction at Lawrence Livermore National Laboratory is presented, along with the underlying motivations. Within this context, high-gradient X-band technology, used in conjunction with fiber-based photocathode drive laser and diode pumped solid-state interaction laser technologies, will be shown to offer optimal performance for high gamma-ray spe...

Three-dimensional theory of weakly nonlinear Compton scattering

Nonlinear effects are known to occur in light sources when the wiggler parameter, or normalized 4-potential, A=e−AμAμ/m0c, approaches unity. In this paper, it is shown that nonlinear spectral features can appear at arbitrarily low values of A if the fractional bandwidth of the undulator, Δϕ−1, is sufficiently small and satisfies the condition A2Δϕ∼1. Consequences for the spectral brightness of Compton scattering light sources are outlined. Compton and Thomson scattering theories are compared with the Klein–Nishina cross-section formula to highlight differences in the case of narrow band gamma-ray operation. A weakly nonlinear Compton scattering theory is developed in one (plane wave) and three (local plane wave approximation) dimensions. Analytical models are presented and benchmarked against numerical calculations solving the Lorentz force equation with a fourth-order Runge–Kutta algorithm. Finally, narrow band gamma-ray spectra are calculated for realistic laser and electron beams.

Multi-bunch Operation of a Laser-Compton X-ray Source Based on Compact X-band Accelerator Technology

Multi-bunch operation of a 35 keV, laser-Compton x-ray source in which a single laser pulse interacts with a train of closely spaced electron bunches is demonstrated for the first time.

Compton scattering sources and applications at LLNL

We report the design and current status of a monoenergetic laser‐based Compton scattering 0.5–2.5 MeV γ‐ray source. Previous nuclear resonance fluorescence results and future linac and laser developments for the source are presented.