Combination PBPM and Slits at the Pohang Light Source

Three combination photon beam position monitor (PBPM) and slits are in use at the photon transfer line (PTL) of the high flux macromolecular X‐ray crystallography (HFMX) beamline at the Pohang Light Source. Each slit, based on a common basic design, drives its two slit plates through a double bellows assembly by two motors. The slits also adopt a turned‐grazing inclination of 30° to restrict the passage of scattered photon beams and to enhance cooling efficiency. One of the slits has been successfully applied with cooling function in order to cool the heat load from a multi‐pole wiggler. This paper describes the design details and design features of the slits and discusses the results of performance tests for their PBPM function. The combined PBPM function can be used for the analysis of the position behaviors of photon beams at the beamline.