Holtz Marcel, Hauf Christoph, Weisshaupt Jannick, Salvador Antonio-Andres Hernandez, Woerner Michael, Elsaesser Thomas
Max-Born-Institut für Nichtlineare Optik und Kurzzeitspektroskopie, 12489 Berlin, Germany.
Struct Dyn. 2017 Jul 19;4(5):054304. doi: 10.1063/1.4991355. eCollection 2017 Sep.
Table-top laser-driven hard x-ray sources with kilohertz repetition rates are an attractive alternative to large-scale accelerator-based systems and have found widespread applications in x-ray studies of ultrafast structural dynamics. Hard x-ray pulses of 100 fs duration have been generated at the Cu K wavelength with a photon flux of up to 10 photons per pulse into the full solid angle, perfectly synchronized to the sub-100-fs optical pulses from the driving laser system. Based on spontaneous x-ray emission, such sources display a particular noise behavior which impacts the sensitivity of x-ray diffraction experiments. We present a detailed analysis of the photon statistics and temporal fluctuations of the x-ray flux, together with experimental strategies to optimize the sensitivity of optical pump/x-ray probe experiments. We demonstrate measurements close to the shot-noise limit of the x-ray source.
具有千赫兹重复率的桌面式激光驱动硬X射线源是基于大型加速器的系统的一种有吸引力的替代方案，并已在超快结构动力学的X射线研究中得到广泛应用。在Cu K波长处已产生持续时间为100 fs的硬X射线脉冲，每个脉冲进入全立体角的光子通量高达10个光子，与来自驱动激光系统的亚100 fs光脉冲完美同步。基于自发X射线发射，此类源表现出一种特殊的噪声行为，这会影响X射线衍射实验的灵敏度。我们对X射线通量的光子统计和时间涨落进行了详细分析，并提出了优化光泵浦/X射线探测实验灵敏度的实验策略。我们展示了接近X射线源散粒噪声极限的测量结果。
