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Optica 7(6), 716 - (2020). doi:10.1364/OPTICA.396728, A critical challenge of pump-probe experiments with x-ray free-electron lasers (XFELs) is accurate synchronization of x-ray and optical pulses. At the European XFEL we observed megahertz rate timing jitter of 24.0±12.4fs., Published by OSA, Washington, DC

Optics letters 44(7), 1650 - 1653 (2019). doi:10.1364/OL.44.001650, Intense, ultrashort, and high-repetition-rate X-ray pulses, combined with a femtosecond optical laser, allow pump-probe experiments with fast data acquisition and femtosecond time resolution. However, the relative timing of the X-ray pulses and the optical laser pulses can be controlled only to a level of the intrinsic error of the instrument which, without characterization, limits the time resolution of experiments. This limitation inevitably calls for a precise determination of the relative arrival time, which can be used after measurement for sorting and tagging the experimental data to a much finer resolution than it can be controlled to. The observed root-mean-square timing jitter between the X-ray and the optical laser at the SPB/SFX instrument at European XFEL was 308 fs. This first measurement of timing jitter at the European XFEL provides an important step in realizing ultrafast experiments at this novel X-ray source. A method for determining the change in the complex refractive index of samples is also presented., Published by OSA, Washington, DC

The Advanced Telecommunications Computing Architecture (ATCA) and Micro Telecommunications Computing Architecture (μTCA) standards, collectively known as xTCA, provide a flexible and scalable infrastructure for designing complex control and data acquisition systems. The xTCA standards are becoming more and more popular in physics applications. Programmable devices, such as Field Programmable Gate Arrays (FPGAs), conventional and Digital Signal Processors (DSPs) are present in Advanced Mezzanine Card (AMC) modules and ATCA blades used in the xTCA crates. Those devices typically boot from non-volatile memories available on the modules. This paper deals with an universal framework and set of tools for upgrading firmware in such devices in xTCA systems. The proposed framework uses a fat pipe region interface of backplane for the firmware data transmission and the Intelligent Platform Management Interface (IPMI) standard for PROM memory management and the control of the upgrade procedure. This is the world's first attempt to implement the firmware upgrade in system not using the JTAG Switch Module (JSM).