近日，日本国立自然科学院分子科学研究所的Yoshitaka Taira及其研究团队取得一项新进展。经过不懈努力，他们计算出轴对称偏振光涡旋激光器产生的伽马射线的空间分布。相关研究成果已于2024年10月30日在国际知名学术期刊《物理评论A》上发表。

据悉，利用李纳-维谢尔势可以计算出高能电子发射的电磁辐射的极化特性和空间分布，这些特性由电子轨道的变化来表征。在涉及电子与激光相互作用的汤姆逊散射或康普顿散射中，电子的横向运动是由激光的电场诱导的。线性和圆极化激光场中发射辐射的极化特性和空间分布已被广泛研究。

在本文中，研究人员使用碲化镉（CdTe）图像传感器测量了由750兆电子伏（MeV）电子束与轴对称极化激光90度碰撞产生的MeV伽马射线的空间分布。这种轴对称极化激光是通过使用一个称为s波片的空间可变延迟器，从线极化激光中产生的，它包含径向和方位角极化的成分。伽马射线的空间分布在中心呈现峰值，类似于线性和圆极化伽马射线，但在整体轮廓上与这两者都有所不同。

这一结果表明，轴对称极化激光产生了不同极化状态的伽马射线。此外，他们观察到轮廓随轴对称极化激光的极化轴而变化，这可能是由于激光极化强度的不均匀分布所致。另外，研究人员还测量了由圆极化光学涡旋激光产生的伽马射线的空间分布，结果显示其轮廓与非涡旋圆极化激光的轮廓相对应。

附：英文原文

Title: Spatial distribution of gamma rays produced by axially symmetric polarized and optical vortex lasers

Author: Yoshitaka Taira

Issue&Volume: 2024/10/30

Abstract: The polarization properties and spatial distribution of electromagnetic radiation emitted from a high-energy electron can be calculated using the Lienard-Wiechert potentials. These properties are characterized by changes in electron orbitals. In Thomson or Compton scattering by relativistic electrons, which involves the interaction between electrons and a laser, the transverse motion of the electrons is induced by the laser's electric field. The polarization characteristics and spatial distribution of emitted radiation in linearly and circularly polarized laser fields have been extensively studied. In this paper, using a CdTe image sensor, the spatial distribution of MeV gamma rays generated by a 90-degree collision between a 750 MeV electron beam and an axially symmetric polarized laser was measured. The axially symmetric polarized laser, which includes radially and azimuthally polarized components, was created from a linearly polarized laser using a spatially variant retarder known as an s-waveplate. The spatial distribution of gamma rays exhibited a peak at the center, similar to linearly and circularly polarized gamma rays, but differed in overall contour from both. This result suggested that axially symmetric polarized lasers generated gamma rays with different polarization states. Moreover, the contour was observed to change with the polarization axis of the axially symmetric polarized laser, likely owing to the nonuniform distribution of the laser's polarization intensity. Additionally, the spatial distribution of gamma rays produced by circularly polarized optical vortex lasers was measured, showing that their contours corresponded to those of nonvortex circularly polarized lasers.

DOI: 10.1103/PhysRevA.110.043525

Source: https://journals.aps.org/pra/abstract/10.1103/PhysRevA.110.043525