Compton Scattered X-Gamma Rays with Orbital Momentum

We study the possibility of producing x-gamma rays with orbital angular momentum by means of the inverse Compton backscattering between a high brightness electron beam and a twisted laser pulse. We use the classical electrodynamics retarded fields for evaluating the orbital angular momentum of the radiation and connecting it to that of the primary laser pulse. We then propose the dimensioning of a linearly polarized x-ray source with orbital angular momentum, starting from the parameters of operating Thomson setups.

Figure 1

Laser field structure for $x_0=0$, $y_0=0$ and (a) $m=0$, (b) $m=1$, $ϵ=1$; (c) $m=2$, $ϵ=1$, (1) $z=0$, (2) $z=0.001\mathrm{mm}$ (3) $z=0.002\mathrm{mm}$.

Figure 2

Scheme and geometry of the OAM $\mathrm{x}\text{−}\gamma$ source. $L$: distance between the source and the screen. ${\underset{\_}{x}}^{\prime }$: position of the generic charge element. $(x,y,z)=(r,\phi ,z)$: position of the observer.

Figure 3

Radiation average intensity for a reference Gaussian case.

Figure 4

$y$ component of the electric field $\underset{\_}{E}$ of the radiation at different times. (a) $t=0.2$, (b) $t=0.4$, (c) $t=0.6\mathrm{ps}$. (d) average intensity for $m=1$, $ϵ=1$.

Figure 5

$y$ component of the electric field $\underset{\_}{E}$ of the radiation at different times. (a) $t=0.2$, (b) $t=0.4$, (c) $t=0.6\mathrm{ps}$. (d) Average intensity for $m=2$, $ϵ=1$.

Figure 6

$z$ component of the angular orbital momentum transverse density $d{L}_z^{\mathrm{OM},\text{rad}}/dxdy$ of the radiation on a screen at 1 m for the cases (a) $m=1$ and (b) $m=2$, with the same parameters as Figs. 4 and 5.