It is known that in the small quantum parameter regime the Breit-Wheeler electron-positron pair creation cross section is extremely sensitive on the photon energy and on the background field. We present the dependence of positron yield on laser intensity in laser-foil interactions with the help of analytical theory and particle-in-cell simulaitons. These particles are emitted in a relatively narrow range of cone angles close to perpendicular direction relative to the laser beam axis. This allows for establishing an in situ intensity diagnostic by measuring the positron current in experiments where peta-watt class lasers are used.

中文翻译：

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通过成对薄膜靶对产生的峰值激光强度进行诊断

众所周知，在小量子参数范围内，布雷特-惠勒电子-正电子对的产生截面对光子能量和背景场极为敏感。我们借助分析理论和细胞内颗粒模拟，介绍了激光与​​箔相互作用中正电子产量对激光强度的依赖性。这些粒子以相对于激光束轴垂直方向接近的相对窄的锥角范围发射。这允许通过在使用千万瓦级激光的实验中测量正电子电流来建立原位强度诊断。