A precision optical calibration module for IceCube-Gen2

A next generation of IceCube is under design including the Precision IceCube Next Generation Upgrade (PINGU) for the neutrino mass ordering and an extended array for astrophysical neutrino sources. A new level of precision is needed in order to guarantee improved performance with respect to IceCube. An improved calibration system will enable a better understanding of the ice and will therefore significantly reduce systematic effects. We present a new instrument called the Precision Optical Calibration Module (POCAM). By keeping the outer topology identical to that of the IceCube Digital Optical Module (DOM), cost-effective construction and deployment is ensured. The design of the POCAM is based on the principle of an inverted integrating sphere. An appropriately placed LED in combination with a diffusing layer on the inside of the sphere results in a nearly homogeneous light emission from the apertures in the spherical housing. The output of the LED is monitored in-situ to high precision, ensuring control over the output from the apertures. The POCAM has been simulated and tested in the framework of Geant4. A prototype POCAM is under construction. We report on the status of the POCAM RandD.