The BAIKAL neutrino experiment: From NT200 to NT200+

Abstract The Baikal Neutrino Telescope has been operating in its NT200 configuration since April, 1998. The telescope has been upgraded in April, 2005 to the 10 Mton scale detector NT200+. It's main physics goal is the detection of signals from high energy neutrino cascades. NT200+ reaches a 3-year sensitivity of 2 × 10 - 7 cm - 2 s - 1 sr - 1 GeV for an all-flavor diffuse cosmic E - 2 neutrino flux for energies 10 2 TeV – 10 5 TeV . Design and sensitivity of NT200+ are described. NT200+ is forming the basic building block of a future km3-scale (gigaton-volume) Baikal Telescope. Research and development work on that next stage detector has started.