Transverse bunch-by-bunch feedback system for time-resolved experiments at PLS-II

A description of the upgraded bunch-by-bunch feedback system for time-resolved experiments at Pohang Light Source II (PLS-II) is provided. The bunch-by-bunch feedback system has been upgraded to increase the single-bunch current in the hybrid fill pattern of the PLS-II facility. The project is part of the SPring-8 and PLS-II collaboration. The main features of the upgrade are to employ a single 500 MHz analog-to-digital converter (ADC) instead of the previous four 125 MHz interleaved ADCs for 500 MHz rate, to replace a single-loop two-dimensional feedback with two independent one-dimensional feedback loops, to implement the tune measurement function with a single bunch, and mainly to implement single-bunch and stretcher control. The realization of a 400 mA hybrid fill pattern including a 10 mA single bunch demonstrates the precision of the upgraded bunch-by-bunch feedback system.

BL-11C Micro-MX: a high-flux microfocus macromolecular-crystallography beamline for micrometre-sized protein crystals at Pohang Light Source II

BL-11C, a new protein crystallography beamline, is an in-vacuum undulator-based microfocus beamline used for macromolecular crystallography at the Pohang Accelerator Laboratory and it was made available to users in June 2017. The beamline is energy tunable in the range 5.0–20 keV to support conventional single- and multi-wavelength anomalous-dispersion experiments against a wide range of heavy metals. At the standard working energy of 12.659 keV, the monochromated beam is focused to 4.1 µm (V) × 8.5 µm (H) full width at half-maximum at the sample position and the measured photon flux is 1.3 × 1012 photons s−1. The experimental station is equipped with a Pilatus3 6M detector, a micro-diffractometer (MD2S) incorporating a multi-axis goniometer, and a robotic sample exchanger (CATS) with a dewar capacity of 90 samples. This beamline is suitable for structural determination of weakly diffracting crystalline substances, such as biomaterials, including protein, nucleic acids and their complexes. In addition, serial crystallography experiments for determining crystal structures at room temperature are possible. Herein, the current beamline characteristics, technical information for users and some recent scientific highlights are described.

The Status and the Future of the PLS-II

Through construction and operation over the last 25 years, the Pohang light source (PLS) and the PLS-II (upgrade of PLS) have played a key role in developments in the vacuum and semiconductor industries, civil engineering, surveying, and even in the building technology of Korea. The PLS has actively contributed to developments in chemical engineering and bio-technology, which directly affect industry and people’s life. In this article, the status of the PLS-II will be described, and the future of the PLS-II will be introduced.

Upgrade of BL-5C as a highly automated macromolecular crystallography beamline at Pohang Light Source II

BL-5C is an in-vacuum undulator beamline dedicated to macromolecular crystallography (MX) at the 3 GeV Pohang Light Source II in Korea. The beamline delivers X-ray beams with a focal spot size of 200 µm × 40 µm (FWHM, H × V) over the energy range 6.5–16.5 keV. The measured flux is 7 × 1011 photons s−1 at 12.659 keV through an aperture size of 50 µm. The experimental station is newly equipped with the photon-counting detector EIGER 9M, the multi-axis micro-diffractometer MD2, and a robotic sample changer with a high-capacity dewar. These instruments enable the operation of this beamline as an automated MX beamline specialized in X-ray fragment screening. This beamline can collect more than 400 data sets a day without human intervention, and a difference map can be automatically calculated by using the data processing pipeline for ligand or fragment identification.

Comparative study of hard X-ray undulator beamline performance in the Korean 4GSR and the PLS-II

A new light source based on the electron storage ring, dubbed the “diffraction-limited storage ring” (DLSR) to keep the full intrinsic wave nature of X-rays had been proposed since the early stage of storage ring history and has finally been developed successfully, and an upgrade and a new construction programs have now chosen in the worldwide synchrotron facilities. The construction of the so-called “4th generation storage ring” (4GSR), which is a newly-coined term aiming in the same direction, was decided in Korea. The Korean 4GSR is expected to be 10–100 times brighter than the Pohang Light Source-II (PLS-II). Hard X-ray undulator beamlines will benefit from the 4GSR due to its low emittance approaching the diffraction limit. In the PLS-II, more than 10 hard X-ray undulator beamlines are currently in operation. We present a comparative study of the representative hard X-ray undulator beamlines by using the cutting-edge diffraction-spectroscopy techniques in the PLS-II and the 4GSR for better understanding the upcoming light source in Korea. The figures-of-merit of the two specific experimental techniques, resonant inelastic X-ray scattering (RIXS) and resonant X-ray emission spectroscopy (RXES), are discussed for comparison of the two light sources. Both RIXS and RXES are sometimes referred to as a “renaissance” in X-ray science and are, therefore, strongly expected to be adopted in the 4GSR beamlines.

Development of XANES nanoscopy on BL7C at PLS-II

X-ray absorption near-edge structure (XANES) imaging is a powerful tool to visualize the chemical state distribution of transition-metal-based materials at synchrotron radiation facilities. In recent years, the electrochemical working rechargeable battery has been the most studied material in XANES imaging owing to the large increase of portable electronics and electric vehicles. This work acknowledges the importance of battery analysis and has developed the XANES imaging system on BL7C at Pohang Light Source-II (PLS-II). BL7C employs an undulator taper configuration to obtain an energy band >130 eV near the K-absorption edge of the target element with a minimum energy interval >0.2 eV. While measuring energy-dependent images, the zone plate translation maintains the best focus, and then various data processes such as background correction, image registration and clustering allow single XANES spectrum extraction and chemical distribution mapping. Here, the XANES imaging process is described, the XANES spectrum quality is identified and the chemical states of the partially charged cathode material used in lithium-ion batteries as an application example are examined.