Mitsuhiro Yamaga

Bio: Mitsuhiro Yamaga is an academic researcher. The author has contributed to research in topics: SACLA & Data acquisition. The author has an hindex of 7, co-authored 26 publications receiving 1508 citations.

A compact X-ray free-electron laser emitting in the sub-ångström region

Abstract: Researchers report sub-angstrom fundamental-wavelength lasing at the SPring-8 Angstrom Compact Free-Electron Laser in Japan. The output has a maximum power of more than 10 GW, a pulse duration of 10−14 s and a lasing wavelength of 0.634 A.

Generation of narrow-band X-ray free-electron laser via reflection self-seeding

Abstract: X-ray free-electron lasers (XFELs)1,2 are widely operated on the basis of self-amplified spontaneous emission (SASE)3,4, where spontaneous radiation from the electron beam is amplified along the magnetic field in undulators. Despite their high intensities, SASE-XFELs have a broad spectrum due to the stochastic starting-up process5. To narrow the bandwidth, self-seeding has been proposed6,7 and recently demonstrated8,9, where the seed pulse produced by monochromatizing the SASE-XFELs from the first section of undulators using a thin crystal in transmission geometry is amplified in the remaining undulators. Here, we present an efficient self-seeding scheme using the Bragg reflection to produce a seed pulse. We applied this scheme to SPring-8 Angstrom Compact free-electron LAser (SACLA)10, and produced nearly Fourier-transform-limited XFEL pulses that correspond to an increase in spectral brightness by a factor of six compared with SASE-XFELs. This achievement will not only enhance the throughput of present XFEL experiments but also should open new opportunities for X-ray science. A nearly Fourier-limited X-ray free-electron laser beam is generated by a self-seeding scheme. The beam in the first half of the undulators is monochromatized via Bragg reflection, and is subsequently amplified in the remaining undulators.

A soft X‐ray free‐electron laser beamline at SACLA: the light source, photon beamline and experimental station

Abstract: The design and performance of a soft X-ray free-electron laser (FEL) beamline of the SPring-8 Compact free-electron LAser (SACLA) are described. The SPring-8 Compact SASE Source test accelerator, a prototype machine of SACLA, was relocated to the SACLA undulator hall for dedicated use for the soft X-ray FEL beamline. Since the accelerator is operated independently of the SACLA main linac that drives the two hard X-ray beamlines, it is possible to produce both soft and hard X-ray FEL simultaneously. The FEL pulse energy reached 110 µJ at a wavelength of 12.4 nm (i.e. photon energy of 100 eV) with an electron beam energy of 780 MeV.

Data acquisition system for X-ray free-electron laser experiments at SACLA

Abstract: A data acquisition system for X-ray free-electron laser experiments at SACLA has been developed. The system has been designed for reliable shot-to-shot data storage with a high data stream greater than 4 Gbps and massive data analysis. Configuration of the system and examples of prompt data analysis during experiments are presented. Upgrade plans for the system to extend flexibility are described.

Software for the data analysis of the arrival-timing monitor at SACLA.

Abstract: X-ray free-electron laser (XFEL) pulses from SPring-8 Angstrom Compact free-electron LAser (SACLA) with a temporal duration of <10 fs have provided a variety of benefits in scientific research. In a previous study, an arrival-timing monitor was developed to improve the temporal resolution in pump-probe experiments at beamline 3 by rearranging data in the order of the arrival-timing jitter between the XFEL and the synchronized optical laser pulses. This paper presents Timing Monitor Analyzer (TMA), a software package by which users can conveniently obtain arrival-timing data in the analysis environment at SACLA. The package is composed of offline tools that pull stored data from cache storage, and online tools that pull data from a data-handling server in semi-real time during beam time. Users can select the most suitable tool for their purpose, and share the results through a network connection between the offline and online analysis environments.

Phase Retrieval with Application to Optical Imaging: A contemporary overview

Abstract: i»?The problem of phase retrieval, i.e., the recovery of a function given the magnitude of its Fourier transform, arises in various fields of science and engineering, including electron microscopy, crystallography, astronomy, and optical imaging. Exploring phase retrieval in optical settings, specifically when the light originates from a laser, is natural since optical detection devices [e.g., charge-coupled device (CCD) cameras, photosensitive films, and the human eye] cannot measure the phase of a light wave. This is because, generally, optical measurement devices that rely on converting photons to electrons (current) do not allow for direct recording of the phase: the electromagnetic field oscillates at rates of ~1015 Hz, which no electronic measurement device can follow. Indeed, optical measurement/detection systems measure the photon flux, which is proportional to the magnitude squared of the field, not the phase. Consequently, measuring the phase of optical waves (electromagnetic fields oscillating at 1015 Hz and higher) involves additional complexity, typically by requiring interference with another known field, in the process of holography.

Highly coherent and stable pulses from the FERMI seeded free-electron laser in the extreme ultraviolet

Abstract: Researchers demonstrate the FERMI free-electron laser operating in the high-gain harmonic generation regime, allowing high stability, transverse and longitudinal coherence and polarization control.

X-Rays and Extreme Ultraviolet Radiation: Principles and Applications

Abstract: This self-contained, comprehensive book describes the fundamental properties of soft x-rays and extreme ultraviolet (EUV) radiation and discusses their applications in a wide variety of fields, including EUV lithography for semiconductor chip manufacture and soft x-ray biomicroscopy. The author begins by presenting the relevant basic principles such as radiation and scattering, wave propagation, diffraction, and coherence. He then goes on to examine a broad range of phenomena and applications. The topics covered include EUV lithography, biomicroscopy, spectromicroscopy, EUV astronomy, synchrotron radiation, and soft x-ray lasers. He also provides a great deal of useful reference material such as electron binding energies, characteristic emission lines and photo-absorption cross-sections. The book will be of great interest to graduate students and researchers in engineering, physics, chemistry, and the life sciences. It will also appeal to practicing engineers involved in semiconductor fabrication and materials science.

DIALS: implementation and evaluation of a new integration package

Abstract: The DIALS project is a collaboration between Diamond Light Source, Lawrence Berkeley National Laboratory and CCP4 to develop a new software suite for the analysis of crystallographic X-ray diffraction data, initially encompassing spot finding, indexing, refinement and integration. The design, core algorithms and structure of the software are introduced, alongside results from the analysis of data from biological and chemical crystallography experiments.