Development of a linac-based LEPD experimental station for surface structure analysis and coordination with synchrotron radiation ARPES

We report on the development of a low-energy positron diffraction (LEPD) experimental station for surface structure analysis using a linear electron accelerator (linac)-based slow-positron beam. LEPD is the positron counterpart of low-energy electron diffraction (LEED) and is expected to offer higher accuracy in surface structure determination compared to LEED. The station enables acquisition of LEPD I – V curves within a few hours. It consists of two ultra-high vacuum (UHV) chambers for LEPD measurements and sample preparation, equipped with essential tools for surface preparation and evaluation. A newly designed sample holder has been developed to be compatible with this LEPD station at SPF-A4 of the Slow Positron Facility (SPF) and the angle-resolved photoemission spectroscopy (ARPES) station at BL-13B of the Photon Factory (PF), both located at the Tsukuba campus of the Institute of Materials Structure Science (IMSS), High Energy Accelerator Research Organization (KEK). This system facilitates LEPD and ARPES measurements on the same sample under consistent surface conditions, achieved through identical preparation environments and procedures.