Beam Physics 2013 Workshop
Nov. 28 Thursday 15:00 - 16:00 Center Bldg B250
OIST Seminar "Introduction to 4D Electron Microscopy"
15:00 - 15:15
Dr. Keshav Dani from OIST
"Introduction to 4D Electron Microscopy"
The development of 4D microscopy has the potential to offer new insight into the study of ultrafast dynamics in materials due to its high temporal and spatial resolution capabilities. I will briefly summarize ongoing developments in the field, and potential directions forward.
15:15 - 15:50
Dr. Jinfeng Yang from The Institute of Scientific and Industrial Research, Osaka University
"MeV Electron Diffraction and Microscopy"
The direct visualization of structural dynamic processes in matter occurring on femtosecond time scales over sub-nanometer (even atomic) spatial dimensions has long been a goal in science. Transmission electron microscopy (TEM) is a powerful tool to observe directly the image from specimen with high spatial resolution. When coupled with time resolution, it, which called ultrafast electron microscopy (UEM), would be the strongest tool for the study of ultrafast dynamics in materials. Currently, the UEM with the time-spatial resolution of 10 ns and 10 nm has been achieved in conventional TEM through the use of photo-activated electron source driven by a nanosecond laser in the non-space-charge-limited regime with ns-long pulse length. A large number of important phenomena, i.e. phase transformations, melting, resolidification, nucleation and growth of damage in nanosecond time region, have been investigated. For the high time resolution development, a multi-shot (or stroboscopic) UEM, where as few as one electron in a pulse being sufficient for a ~100 MHz repetition rate laser system, has been proposed. However, to accumulate more signals, one need merely cycle the experiment for a longer time, within the limits of the stability of the microscope and the sample.
To overcome the space-charge limitation, we have proposed and designed a femtosecond time-resolved relativistic-energy electron microscopy using a photocathode radio-frequency (RF) electron gun. We started the femtosecond time-resolved electron microscopy project from 2010: (1) in 2012, a first prototype of RF gun based relativistic-energy TEM has been constructed at Osaka University. Both the static measurements of both relativistic-energy electron diffraction and image have been succeeded. (2) We have developed a new RF gun under the collaboration with KEK to generate a low-emittance femtosecond-bunch electron beam: 100 fs and 0.2 mm-mrad, which are essential for the achievement of nm-fs space-time resolution in future. (3) We have succeeded to develop a RF gun based ultrafast relativistic-energy electron diffraction, which has been used for the ultrafast dynamic study on phase transformation with femtosecond time resolution.
In this talk, the activities on UED and UEM are introduced. The requirements and limitations of the beam parameters in UEM are reviewed. The concept and design of RF gun based relativistic-energy TEM prototype are reported. The beam dynamics and challenges in femtosecond RF gun will be discussed. Finally, some demonstrations of the relativistic-energy TEM images, the single-shot and time-resolved UED measurements are reported.
Beam Physics Youth Workshop 2013
Nov. 30 Saturday 9:00 - 12:00 Seaside House
Seminar "Learning from experienced persons"
9:00 - 10:25
Dr. Atsushi Miura from NIHON KOSHUHA Co., Ltd.
"Experiences on High- Power Microwave Technology on Accelerator Science"
I would like to talk on various topics from my 20 years experiences in developing and supporting hardware components
on UHF, L- band, S, C- and X-band high frequency devices. These devices are key to run accelerators, and requires
a lots of technical knowledge, and sometimes painful work. There are highly technical challenges and dramatic successes.
I want to give my message to students and guide them to attractive technical R&D field of Japanese top skillful teamwork.
10:35 - 12:00
Dr. Sadao Miura from Mitsubishi Heavy Industries LTD
"C-band Accelerator Construction at SACLA: X-ray Free Electron Laser"
RIKEN has constructed SACLA X-ray FEL at SPring-8 site, and providing coherent X-ray beams to various experiments. Mitsubishi Heavy Industry contributed accelerator technology development and mass production of most of all components; accelerating tubes of C-band and S-band frequency, RF pulse compressors and waveguide system. We successfully completed this mission before the due date 2010 March. I will explain fabrication processes, quality control in mass production and results on C-band accelerating structure, RF pulse compressor.
Nov. 30 Saturday 13:00 - 15:00 Seaside House
Dr. Saitoh Koh from Eco Topia Science Institute, Nagoya University
"Electron Vortex Beam -- A unique propagation mode of electron waves with helical wavefronts
Electron vortex beam is a unique propagation mode of electrons, which have helical wavefronts. After the experimental realization of electron vortex beams in 2010, its physical properties and interaction with matters have been a center of attention. This lecture provides an introduction of electron vortex beams. Firstly, the basic properties of the electron vortex beam are explained and then recent studies on the vortex beam will be overviewed.