2008 IceCube Update - Section 9
IX. FUTURE PLANS
IceCube completion is scheduled for 2011. In addition to the 80 baseline strings, we are also developing a Deep Core infill array. Deep Core will consist of 6 additional strings with a smaller, 72 m grid spacing. The DOMs will use new phototubes with 25% higher quantum efficiency. They will be spaced every 7 m in the deepest, clearest 350 m of ice. In addition, the rest of IceCube will serve as a veto region surrounding Deep Core, allowing for the rejection of cosmic-ray muons and other non-contained backgrounds. The higher granularity, improved optical sensitivity and surrounding veto will give Deep Core a much lower threshold than IceCube, as low as 10 GeV.
IceCube collaborators are also studying prototype radio and acoustic neutrino detectors. These are sensitive to coherent radio-Cherenkov emission from neutrino-induced electromagnetic and hadronic showers and the shock-wave produced by local heating from neutrino induced showers respectively. The radio and acoustic signals should have much larger absorption lengths than light, so these techniques might be usable to build a much larger (100 km3)array than IceCube. However, because of the technique used, the array would have a much higher energy threshold, perhaps (1017 eV).