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The NEMO Collaboration

Publications and source records attributed to The NEMO Collaboration.

2 recordsLinked to original sources
arXiv2009

Measurement of the Double Beta Decay Half-life of 150-Nd and Search for Neutrinoless Decay Modes with the NEMO-3 Detector

The half-life for double beta decay of 150-Nd has been measured by the NEMO-3 experiment at the Modane Underground Laboratory. Using 924.7 days of data recorded with 36.55 g of 150-Nd the half-life for 2nubb decay is measured to be T_1/2^2nu = (9.11+0.25_-0.22}(stat.) +- 0.63 (syst.)) x 10^18 years. The observed limit on the half-life for neutrinoless double beta decay is found to be T_1/2^{0nu} > 1.8 x 10^22 years at 90 % Confidence Level. This translates into a limit on the effective Majorana neutrino mass of <4.0-6.3 eV if the nuclear deformation is taken into account. We also set limits on models involving Majoron emission, right-handed currents and transitions to excited states.

hep-ex↗
arXiv2008

NEMO-\onde: a submarine station for real-time monitoring of acoustic background installed at 2000 m depth in the Mediterranean Sea

The NEMO (NEutrino Mediterranean Observatory) Collaboration installed, 25 km E offshore the port of Catania (Sicily) at 2000 m depth, an underwater laboratory to perform long-term tests of prototypes and new technologies for an underwater high energy neutrino km$^3$-scale detector in the Mediterranean Sea. In this framework the collaboration deployed and successfully operated for about two years, starting form January 2005, an experimental apparatus for on-line monitoring of deep-sea noise. The station was equipped with 4 hydrophones and it is operational in the range 30 Hz - 43 kHz. This interval of frequencies matches the range suitable for the proposed acoustic detection technique of high energy neutrinos. Hydrophone signals were digitized underwater at 96 kHz sampling frequency and 24 bits resolution. A custom software was developed to record data on high resolution 4-channels digital audio file. This paper deals with the data analysis procedure and first results on the determination of sea noise sound pressure density curves. The stored data library, consisting of more than 2000 hours of recordings, is a unique tool to model underwater acoustic noise at large depth, to characterise its variations as a function of environmental parameters, biological sources and human activities (ship traffic, ...), and to determine the presence of cetaceans in the area.

astro-ph↗