The POCAM as self-calibrating light source for the IceCube Upgrade

Abstract: The planned IceCube Upgrade, consisting of seven new instrumentation strings, will be installed at the South Pole within 2022/2023. The focus of this upgrade is calibration, reduction of systematic uncertainties and atmospheric neutrino physics. Within this scope, the "Precision Optical Calibration Module" (POCAM) will be installed at a number of positions on these new strings, to act as a calibration light source. The POCAM is an in-situ self-calibrating, isotropic, nanosecond light source that emits flashes of adjustable intensity and pulse duration. The isotropy is achieved using a teflon integrating sphere which further allows the calibration of the total number of emitted photons per pulse, using the integrated sensors. Prototypes have been deployed and operated within the GVD telescope in Lake Baikal and within the STRAW experiment in the Pacific Ocean. We present POCAM results and experiences from the GVD and STRAW installations as well as first IceCube sensitivity studies and the following design prospects for this next-generation POCAM iteration.