Production of Highly Polarized Positron Beams via Helicity Transfer from Polarized Electrons in a Strong Laser Field
Production of Highly Polarized Positron Beams via Helicity Transfer from Polarized Electrons in a Strong Laser Field
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在强激光场中通过偏振电子的螺旋转移产生高偏振正电子束
DOI：
10.1103/physrevlett.125.044802
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发表时间：
2020
影响因子：
8.6
通讯作者：
Hu Hua-Si
中科院分区：
文献类型：
--
作者：
Li Yan-Fei;Chen Yue-Yue;Wang Wei-Min;Hu Hua-Si
从理论上研究了超强圆偏振激光脉冲与纵向自旋极化的超相对论电子束相互作用过程中，通过非线性Breit-Wheeler过程产生的高极化正电子束。在局域恒场近似下发展了一种新的蒙特卡罗方法，该方法采用完全自旋分辨的量子几率，考虑了强激光场中的三维偏振效应。产生的正电子通过高能光子的介质从极化的电子转移到纵向极化。当高能正电子以较小的偏转角运动时，极化转移效率可接近100%。这种方法简化了后选择过程，以便在未来的应用中产生高质量的正电子束。在一个可行的方案中，可以在飞秒时间尺度内获得高度极化(40%-65%)、强度(/束团)、准直(5-70mrad)的正电子束。纵向极化正电子源在高能物理和材料科学中有很好的应用前景。
The production of a highly polarized positron beam via nonlinear Breit-Wheeler processes during the interaction of an ultraintense circularly polarized laser pulse with a longitudinally spin-polarized ultrarelativistic electron beam is investigated theoretically. A new Monte Carlo method employing fully spin-resolved quantum probabilities is developed under the local constant field approximation to include three-dimensional polarization effects in strong laser fields. The produced positrons are longitudinally polarized through polarization transferred from the polarized electrons by the medium of high-energy photons. The polarization transfer efficiency can approach 100% for the energetic positrons moving at smaller deflection angles. This method simplifies the postselection procedure to generate high-quality positron beams in further applications. In a feasible scenario, a highly polarized (40%–65%), intense (/bunch), collimated (5–70 mrad) positron beam can be obtained in a femtosecond timescale. The longitudinally polarized positron sources are desirable for applications in high-energy physics and material science.