Studies of a three-stage dark matter and neutrino observatory based on multi-ton combinations of liquid xenon and liquid argon detectors

► We propose a 3-stage DM and Iˆ1/2 observatory based on multi-ton LXe and LAr detectors. ► This work is a quantitative study of the topics in Astropart. Phys. 31 (2009) 63-74. ► WIMP cross-sections and masses could be measured with sensitivity of 10-47cm2. ► 0ν2β decay could be observed for 136Xe with sensitivity to half-lives 10E27-10E28 y. ► The pp solar ν spectrum, and ν flux from a Galactic SN, could also be measured.