Co-flow injection for serial crystallography at X-ray free-electron lasers

Serial femtosecond crystallography (SFX) is a powerful technique that exploits X-ray free-electron lasers to determine the structure of macromolecules at room temperature. Despite the impressive exposition of structural details with this novel crystallographic approach, the methods currently available to introduce crystals into the path of the X-ray beam sometimes exhibit serious drawbacks. Samples requiring liquid injection of crystal slurries consume large quantities of crystals (at times up to a gram of protein per data set), may not be compatible with vacuum configurations on beamlines or provide a high background due to additional sheathing liquids present during the injection. Proposed and characterized here is the use of an immiscible inert oil phase to supplement the flow of sample in a hybrid microfluidic 3D-printed co-flow device. Co-flow generation is reported with sample and oil phases flowing in parallel, resulting in stable injection conditions for two different resin materials experimentally. A numerical model is presented that adequately predicts these flow-rate conditions. The co-flow generating devices reduce crystal clogging effects, have the potential to conserve protein crystal samples up to 95% and will allow degradation-free light-induced time-resolved SFX.

Compact LWFA-Based Extreme Ultraviolet Free Electron Laser: Design Constraints

The combination of advanced high-power laser technology, new acceleration methods and achievements in undulator development offers the opportunity to build compact, high-brilliance free electron lasers driven by a laser wakefield accelerator. Here, we present a simulation study outlining the main requirements for the laser–plasma-based extreme ultraviolet free electron laser setup with the aim to reach saturation of the photon pulse energy in a single unit of a commercially available undulator with the deflection parameter K0 in the range of 1–1.5. A dedicated electron beam transport strategy that allows control of the electron beam slice parameters, including collective effects, required by the self-amplified spontaneous emission regime is proposed. Finally, a set of coherent photon radiation parameters achievable in the undulator section utilizing the best experimentally demonstrated electron beam parameters are analyzed. As a result, we demonstrate that the ultra-short, few-fs-level pulse of the photon radiation with the wavelength in the extreme ultraviolet range can be obtained with the peak brilliance of ∼7×1028 photons/pulse/mm2/mrad2/0.1%bw.

Peak Shift of Coherent Edge Radiation Spectrum Depending on Radio Frequency Field Phase of Accelerator

Spectra of coherent edge radiation (CER) were observed at the S-band linac facility of Kyoto University Free Electron Laser. A local maximum was observed in the CER spectrum on-crest operation of the radio frequency (RF) field. As the phase of the RF field was shifted from the crest, the frequency of the maximum decreased, and the CER spectrum approached a spectrum of Gaussian-distributed electrons in a bunch. It was found that this strange spectrum can be explained by a model in which a satellite pulse exists around a main pulse in the electron bunch. Furthermore, it demonstrated that CER is an effective tool for monitoring the shape of the electron bunch.

Prototype characterization of a charge-integration pixel detector readout chip with in-pixel A/D conversion

HYLITE (High dYmamic range free electron Laser Imaging deTEctor) is a hybrid pixel detector readout chip, which is designed for advanced light sources such as X-ray Free Electron Laser (XFEL) and diffraction-limited storage rings. It is a charge-integration readout chip which has three gains for different dynamic ranges and automatic gain-switching function. The full dynamic range covered by HYLITE is 1 ∼ 104 photons with an energy of 12 keV for each pixel in every shot. In-pixel ADC is designed to achieve front-end digitization and a 10 kHz continuous frame rate. HYLITE0.1 is the first prototype chip for functional verification that was produced in CMOS 0.13 μm technology. It consists of a pixel array with 6 × 12 pixels and a periphery with full standalone operation features. The size of each pixel is 200 μm × 200 μm. Three design variations of pixels with different integrating capacitance and structures were designed to optimize between area and performance. A 10-bit Wilkinson ADC is integrated in each pixel to digitize the outputs of the pre-amplifier. Therefore, analog signal transmission of long distance is avoided and a frame rate of 10 kHz can be achieved. In this paper, we present the design of HYLITE0.1 and the test results of this prototype chip.