Technical Overview of the PAL-XFEL Conventional Facility

Pohang Accelerator Laboratory (PAL) has finished construction of a 1,110m long 10GeV X-ray free electron laser (XFEL) linear accelerator building in FY2015. In order to secure high-sensitive of XFEL accelerating devices, more advanced and well proven technologies were adopted in the design of the building. These are the ground improvement underneath the tunnel and tunnel structure itself against the possible ground deformation, air conditioning system to maintain the temperature and humidity in the tolerable ranges and architectural zoning. In this paper we describe the features of design and construction of the XFEL accelerator building.