少周期激光与锥靶相互作用产生的偏振分辨阿秒伽马射线发射
Polarization-resolved attosecond gamma-ray emission from few-cycle laser interactions with cone targets
中文总结 AI 辅助
本研究通过QED-PIC模拟，利用少周期激光辐照锥靶产生了偏振度高、持续时间短的MeV级阿秒γ射线脉冲，该脉冲可用于相关物理过程研究。
中文摘要 AI 辅助
将单束少周期激光脉冲辐照到锥靶上，可产生MeV量级的线偏振阿秒γ射线脉冲。电子层从锥壁周期性提取后被加速，其与反向传播的反射阿秒场相互作用，通过非线性康普顿散射（NCS）产生高能光子，形成阿秒γ射线脉冲。本研究采用二维量子电动力学粒子模拟（QED-PIC）对该相互作用进行建模，模拟过程解析了发射期间的电子自旋和光子偏振。结果显示，最短等效持续时间为300 as，对应的线偏振度为0.78；光子光谱延伸至6 MeV，高能范围内的线偏振度达到0.88；在宽动量角范围内收集两个发射方向的光子时，线偏振度仍保持较高水平。对锥张角及耦合激光-等离子体参数的扫描显示，光子数量、平均光子能量与偏振之间存在权衡关系。这类高度偏振的阿秒γ射线脉冲可用于研究超快核动力学及强场量子电动力学中的偏振依赖过程。
英文摘要
Linearly polarized attosecond $γ$-ray pulses in the MeV range are generated from a cone target irradiated by a single few-cycle laser pulse. Electron layers are periodically extracted from the cone walls and subsequently accelerated. Their interaction with the counter-propagating reflected attosecond field produces high-energy photons through nonlinear Compton scattering (NCS), forming attosecond $γ$-ray pulses. We model this interaction using two-dimensional quantum electrodynamics particle-in-cell (QED-PIC) simulations that resolve electron spin and photon polarization during emission. The results show a shortest equivalent duration of $300\,\mathrm{as}$, with a corresponding linear polarization degree of 0.78. The photon spectrum extends to $6\,\mathrm{MeV}$, and the linear polarization degree in the high-energy range reaches 0.88. The linear polarization degree remains high when photons from both emission directions are collected over wide momentum-angle ranges. Scans over the cone opening angle and the coupled laser-plasma parameters reveal tradeoffs among photon number, mean photon energy, and polarization. Such highly polarized attosecond $γ$-ray pulses could be used to investigate ultrafast nuclear dynamics and polarization-dependent processes in strong-field quantum electrodynamics.
