The automatic calibration unit in JUNO

This paper describes the design and construction of automatic calibration unit (ACU) for JUNO experiment. The ACU is a fully automated mechanical system. It capable deploying multiple radioactive sources, an ultraviolet (UV) laser source, or auxiliary sensor such as temperature sensor, one at time, into central detector along axis. designed primary tool to precisely calibrate energy scale detector, aligning timing photosensors, partially monitoring position-dependent variations.