  Jiangmen Underground Neutrino Observatory (JUNO) is designed to determine the
neutrino mass hierarchy using a 20 kton liquid scintillator detector. To
calibrate detector boundary effect, the Guide Tube Calibration System (GTCS)
has been designed to deploy a radioactive source along a given longitude on the
outer surface of the detector. In this paper, we studied the physics case of
this system via simulation, which leads to a mechanical design.
