The possibility to probe new physics scenarios of light Majorana neutrino exchange and right-handed currents at the planned next generation neutrinoless double β decay experiment SuperNEMO is discussed. Its ability to study different isotopes and track the outgoing electrons provides the means to discriminate different underlying mechanisms for the neutrinoless double β decay by measuring the decay half-life and the electron angular and energy distributions.a

We review the present status of the Baikal Neutrino Project. The construction and performance of the large deep underwater Cherenkov detector NT-200 with 192 PMTs , which is currently taking data in Lake Baikal, are described. Some results from intermediate detector stages are presented.

We present the results of a search for high energy extraterrestrial neutrinos with the Baikal underwater Cherenkov detector NT200, based on data taken in 1998 -2003. Upper limits on the diffuse fluxes of ν e + ν µ + ν τ , predicted by several models of AGN-like neutrino sources, are derived. For an E −2 behavior of the neutrino Preprint submitted to Elsevier Science 2 March 2018 spectrum, our limit is E 2 Φ ν (E) < 8.1 × 10 −7 cm −2 s −1 sr −1 GeV over an neutrino energy range 2 × 10 4 ÷ 5 × 10 7 GeV. The upper limit on the resonantν e diffuse flux is Φν e <3.3×10 −20 cm −2 s −1 sr −1 GeV −1 .

The development of BiPo detectors is dedicated to the measurement of extremely high radiopurity in 208 Tl and 214 Bi for the SuperNEMO double beta decay source foils. A modular prototype, called BiPo-1, with 0.8 m 2 of sensitive surface area, has been running in the Modane Underground Laboratory since February, 2008. The goal of BiPo-1 is to measure the different components of the background and in particular the surface radiopurity of the plastic scintillators that make up the detector. The first phase of data collection has been dedicated to the measurement of the radiopurity in 208 Tl. After more than one year of background measurement, a surface activity of the scintillators of A( 208 Tl) = 1.5 µBq/m 2 is reported here. Given this level of background, a larger BiPo detector having 12 m 2 of active surface area, is able to qualify the radiopurity of the SuperNEMO selenium double beta decay foils with the required sensitivity of A( 208 Tl) < 2 µBq/kg (90% C.L.) with a six month measurement.

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