Requirements for a New Detector at the South Pole Receiving an Accelerator Neutrino Beam

Abstract

There are recent considerations to increase the photomultiplier density in the IceCube detector array beyond that of DeepCore, which will lead to a lower detection threshold and a huge fiducial mass for the neutrino detection. This initiative is known as "Phased IceCube Next Generation Upgrade" (PINGU). We discuss the possibility to send a neutrino beam from one of the major accelerator laboratories in the Northern hemisphere to such a detector. Such an experiment would be unique in the sense that it would be the only neutrino beam where the baseline crosses the Earth's core. We study the detector requirements for a beta beam, a neutrino factory beam, and a superbeam, where we consider both the cases of small theta_13 and large theta_13, as suggested by the recent T2K and Double Chooz results. We illustrate that a flavor-clean beta beam best suits the requirements of such a detector, in particular, that PINGU may replace a magic baseline detector for small values of theta_13 -- even in the absence of any energy resolution capability. For large theta_13, however, a single-baseline beta beam experiment cannot compete if it is constrained by the CERN-SPS. For a neutrino factory, because of the missing charge identification possibility in the detector, a very good energy resolution is required. If this can be achieved, especially a low energy neutrino factory, which does not suffer from the tau contamination, may be an interesting option for large theta_13. For the superbeam, where we use the LBNE beam as a reference, electron neutrino flavor identification and statistics are two of the main limitations. Finally, we demonstrate that, at least in principle, neutrino factory and superbeam can measure the density of the Earth's core to the sub-percent level for sin^2 2theta_13 larger than 0.01.