Radiation shielding design of the PAL-XFEL

Abstract

The construction of the Pohang Accelerator Laboratory X-ray Free Electron Laser (PAL-XFEL) started in 2011. The PAL-XFEL is designed to generate X-rays using 10 GeV, 0.2 nC electron beams. For the radiation shielding design, a beam-loss scenario suitable for the PAL-XFEL should be established. The beam-loss scenario was determined and categorized as normal or accidental. The electron beam will be shut down automatically when accidental beam-loss occurs. Using this scenario, the thickness of the accelerator and undulator tunnel of the PAL-XFEL was calculated by using the SHIELD11 code, and complicated tunnel structures such as maze entrances, sliding doors, trenches, sleeves, and ducts, were determined under the assumption of a thick iron target by using the FLUKA code. A detailed design of the main beam dump was established, and shielding structures at the front end for suppression of the radiation dose at the experimental area under the accidental beam-loss scenario were considered. The muon production was estimated by using the FLUKA code.