报告题目：Positron Diffraction Experiments in Japan

报告人：Ken Wada (和田 健) Senior Researcher

（Takasaki Advanced Radiation Research Institute, National Institutes for Quantum and Radiological Science and Technology）

报告时间：2017年6月7日（周三）下午15:30-16:30

报告地点：新物理楼多功能报告厅

Dr. Wada graduated from the University of Tokyo in 2000, from then worked as an assistant professor and an associate Professor in the University of Tokyo and High Energy Accelerator Research Organization (KEK), and in 2016 he joined National Institutes for Quantum and Radiological Science and Technology as a senior researcher. Dr. Wada’s interested in Materials Science by Positron Annihilation Techniques and Linac- and RI-based Quantum Beam Techniques. Recently, he is focused on the research topics of atomic structure of material surface using a new novel technique, i.e. total-reflection high-energy positron diffraction (TRHEPD), which is the positron counterpart of reflection high-energy electron diffraction (RHEED). Using TRHEPD, diffraction patterns of the atoms on the topmost surface of materials can be obtained. Dr. Wada and his colleagues also has developed another surface diffraction method by positron, namely, low-energy positron diffraction (LEPD) based on a linac-based slow-positron beam at KEK-SPF and succeeded in obtaining a LEPD pattern for Ge(001)-(2×1).

In this talk, slow-positron beam techniques for positron diffraction experiments and some recent results by TRHEPD at KEK are presented. Current status of the LEPD project is reported together with its initial LEPD pattern. The ongoing plan for surface holographic reconstruction by LEPD is also explained.

欢迎广大师生、特别是对材料表面原子结构感兴趣的师生参加！

邀请人：何春清教授