Thomson backscattering X-rays from ultra-relativistic electron bunches and temporally shaped laser pulses

Abstract

The process of Thomson scattering of an ultra-intense laser pulse by a relativistic electron bunch has been proposed as a way to obtain a bright source of short, tunable and quasi-monochromatic X-ray pulses. The real applicability of such a method depends crucially on the electron-beam quality, the angular and energetic distributions playing a relevant role. In this paper we present the computation of the Thomson-scattered radiation generated by a plane-wave, linearly polarized and flat-top laser pulse, incident on a counterpropagating electron bunch having a sizable angular divergence and a generic energy distribution. Both linear and nonlinear Thomson-scattering regimes are considered and the impact of the rising front of the pulse on the scattered-radiation distribution has been taken into account. Simplified relations valid for long laser pulses and small values of both scattering angle and bunch divergence are also reported. Finally, we apply the results to the cases of backscattering with electron bunches typically produced with both standard radio-frequency-based accelerators and laser-plasma accelerators

Design and optimization of a highly efficient optical multipass system forγ-ray beam production from electron laser beam Compton scattering

“…In the next section, we concentrate on the optimization of the TASD as defined in [5] and we use the expressions of [1,3,4] for numerical calculations. Accordingly, the TASD values for one pass obtained with the beam parameters of Table I are shown in Fig.…”

“…To compute the γ-ray spectrum, one needs to take the electrons and laser beam spatiotemporal shape into account [1,[3][4][5]36]. For a given set of laser beam parameters, we can choose the electron beam beta function at the IP in order to optimize the γ-ray flux.…”

“…However, this physical process exhibits a small cross section: therefore the densities of laser photons and electrons in the collision point must be very high in order to generate a large number of γ-ray photons at each collisions, and the repetition rate of the collisions must be maximized in order to achieve high γ-ray fluxes. As extensively reported elsewhere [1][2][3][4][5] the phase space density of the electron beam and of the laser beam at the collision point are key issues for achieving high fluxes of gamma rays with very small bandwidths, as those typically requested by nuclear physics experiments and applications. In this article, we concentrate on the optical design of the interaction point (IP) of a Compton γ-ray machine which has been proposed for the European Extreme Light Infrastructure "Nuclear Pillar," i.e., the Gamma Beam System (ELI-NP-GBS) [1,3,4,6] project.…”

Ultra-Intense, High Spatio-Temporal Quality Petawatt-Class Laser System and Applications

“…where e and e m are the charge and mass of an electron, c is the speed of light,  is Planck constant, ω and E are the EM field frequency and strength, respectively, [106]) mentioned here is of a paramount importance for the generation of gamma-rays sourced for nuclear applications, both for accelerator based sources and also for laser based sources. When a ≈ 1 or a >> 1 the probabilities of absorbing different number of photons become comparable and the process becomes multiphoton, i.e., the probability has an essentially nonlinear dependence on the field.…”

Transverse effects in the production of x rays with a free-electron laser based on an optical undulator

“…The radiation generated in the Thomson backscattering is usually considered incoherent and calculated by summing at the collector the intensities of the fields produced in single processes by each electron [7][8][9][10][11][12][13]. If the laser pulse is long enough, however, collective effects can establish and become dominant.…”