In the RADAR project described in this Letter of Intent, we propose to deploy a 6 kton liquid argon TPC at the NOvA Far Detector building in Ash River, Minnesota, and expose it to the NuMI beam during NOvA running. It will significantly add to the physics capabilities of the NOvA program while providing LBNE with an R&D program based on full-scale TPC module assemblies. RADAR offers an excellent opportunity to improve the full Homestake LBNE project in physics reach, timeline, costs, and fostering international partnership. The anticipated duration of the projects construction is 5 years, with running happening between 2018 and 2023.
Results are reported from a search for active to sterile neutrino oscillations in the MINOS long-baseline experiment, based on the observation of neutral-current neutrino interactions, from an exposure to the NuMI neutrino beam of $7.07times10^{20}$ protons on target. A total of 802 neutral-current event candidates is observed in the Far Detector, compared to an expected number of $754pm28rm{(stat.)}pm{37}rm{(syst.)}$ for oscillations among three active flavors. The fraction $f_s$ of disappearing umu that may transition to $ u_s$ is found to be less than 22% at the 90% C.L.
