The discovery of astrophysical high-energy neutrinos with IceCube opened the window to neutrino astronomy. With the IceCube-Gen2 high-energy array, an extension that will surround the existing IceCube deep ice detector, the detection rate of cosmic neutrinos will be increased by about an order of magnitude.
The main background of neutrino telescopes such as IceCube consists of muons that are produced by cosmic-ray particles in the atmosphere. A successful method to distinguish neutrinos from this background selects only events that start inside the detector. This can be accomplished by defining a veto layer in the outer region of the detector and considering the amount and timing of Cherenkov light detected in this region.
For the IceCube-Gen2 high-energy array the definition of the veto has to be optimized and new techniques will be introduced, as the geometry will be different and the distances between the optical modules will be larger than in IceCube. In this contribution we present the results of a data-driven analysis that uses real IceCube data to estimate the expected veto energy threshold. In addition, a new veto technique has been developed with the aim of lowering the energy threshold of the current veto procedure. A study of the veto efficiency for different detector geometries of IceCube-Gen2 will be presented as well.