Modulation of high-energy γ-rays by collision of an ultra-high-energyelectron with a tightly focused circularly polarized laser pulse
Yifan Chang, Zirui Zeng, Chang Wang, Zhaonan Long, Youwei Tian
Abstract
Using an ultra-high-energy ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mi>γ</mml:mi> <mml:mo>⩾</mml:mo> <mml:mn>1000</mml:mn> </mml:math> ) electron to collide with laser pulses to generate high-energy <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mi>γ</mml:mi> </mml:math> -rays is an important way to treat cancer. We investigate a method for modulating high-energy <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mi>γ</mml:mi> </mml:math> -rays with higher energy and more collimation using tightly focused circularly polarized laser pulses colliding with an ultra-high-energy electron. Theoretical derivation and numerical simulation within the framework of classical electrodynamics show that higher electron initial energy, stronger laser intensity, and a longer pulse can generate higher <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mi>γ</mml:mi> </mml:math> -ray energy. The high-energy <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mi>γ</mml:mi> </mml:math> -rays generated by an electron with higher initial energies are more collimated. The increase of the laser intensity and the increase of the pulse width will increase the angular range of the high-energy <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mi>γ</mml:mi> </mml:math> -rays. At the same time, the phenomenon of the “jumping point,” in which the radiation energy varies with the laser intensity, was found. Our findings have important implications for modulating better high-energy <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mi>γ</mml:mi> </mml:math> -ray sources.