Three-dimensional time and frequency-domain theory of femtosecond x-ray pulse generation through Thomson scattering

Abstract

The generation of high intensity, ultrashort x-ray pulses enables exciting new experimental capabilities, such as femtosecond pump-probe experiments used to temporally resolve material structural dynamics on atomic time scales. Thomson backscattering of a high intensity laser pulse with a bright relativistic electron bunch is a promising method for producing such high-brightness x-ray pulses in the 10 -100 keV range within a compact facility. While a variety of methods for producing subpicosecond x-ray bursts by Thomson scattering exist, including compression of the electron bunch to subpicosecond bunch lengths and/or colliding a subpicosecond laser pulse in a side-on geometry to minimize the interaction time, a promising alternative approach to achieving this goal while maintaining ultrahigh brightness is the production of a time-correlated (or chirped) x-ray pulse in conjunction with pulse slicing or compression. We present the results of a complete analysis of this process using a recently developed 3D time and frequency-domain code for analyzing the spatial, temporal, and spectral properties an x-ray beam produced by relativistic Thomson scattering. Based on the relativistic differential cross section, this code has the capability to calculate time and space dependent spectra of the x-ray photons produced from linear Thomson scattering for both bandwidth-limited and chirped incident laser pulses. Spectral broadening of the scattered x-ray pulse resulting from the incident laser bandwidth, laser focus, and the transverse and longitudinal phase space of the electron beam were examined. Simulations of chirped x-ray pulse production using both a chirped electron beam and a chirped laser pulse are presented. Required electron beam and laser parameters are summarized by investigating the effects of beam emittance, energy spread, and laser bandwidth on the scattered x-ray spectrum. It is shown that sufficient temporal correlation in the scattered x-ray spectrum to produce sub-100 fs temporal slice resolution can be produced from state-of-the-art, high-brightness electron beams without the need to perform longitudinal compression on the electron bunch.

Theoretical and simulation studies of characteristics of a Compton light source

“…The differential cross section is obtained by setting 0 1;2;3 to zero in Eq. (8) and multiplying the result by a factor of 2 for the summation over the polarizations of the scattered photons [4]. Thus, the differential cross section is given by [11] …”

“…(8), (12), and (13), we can calculate the spatial and energy distributions of a gamma-ray beam produced by Compton scattering of a monoenergetic electron and laser beams with zero transverse beam sizes, i.e., the particle-particle scattering.…”

“…(8) to describe the motion and polarization of the incident electron ðx e ; y e ; z e Þ, the incident photon ðx;ỹ;zÞ, and the scattered photon ðx 0 ;ỹ 0 ;z 0 Þ (Fig. 3).…”

“…Study of beam-beam Compton scattering has been recently reported in [7,8]. However, the algorithms used in these works are based upon the Thomson scattering cross section, i.e., an elastic scattering of electromagnetic radiation by a charged particle without the recoil effect.…”

X-ray phase-contrast imaging with an Inverse Compton Scattering source

“…The detector has been characterized with respect to its Line Spread Function and energy response in order to perform quantitative measurements. X-ray beam [4,5,6] photons/pulse 2 · 10 8…”