Measurement of the atmospheric muon depth intensity relation with the NEMO Phase-2 tower

The results of the analysis of the data collected with the NEMO Phase-2 tower, deployed at 3500 m depth about 80 km off-shore Capo Passero (Italy), are presented. Cherenkov photons detected with the photomultipliers tubes were used to reconstruct the tracks of atmospheric muons. Their zenith-angle distribution was measured and the results compared with Monte Carlo simulations. An evaluation of the systematic effects due to uncertainties on environmental and detector parameters is also included. The associated depth intensity relation was evaluated and compared with previous measurements and theoretical predictions. With the present analysis, the muon depth intensity relation has been measured up to 13 km of water equivalent.Comment: submitted to Astroparticle Physic

Long term monitoring of the optical background in the Capo Passero deep-sea site with the NEMO tower prototype

The NEMO Phase-2 tower is the first detector which was operated underwater for more than 1 year at the "record" depth of 3500 m. It was designed and built within the framework of the NEMO (NEutrino Mediterranean Observatory) project. The 380 m high tower was successfully installed in March 2013 80 km offshore Capo Passero (Italy). This is the first prototype operated on the site where the Italian node of the KM3NeT neutrino telescope will be built. The installation and operation of the NEMO Phase-2 tower has proven the functionality of the infrastructure and the operability at 3500 m depth. A more than 1 year long monitoring of the deep water characteristics of the site has been also provided. In this paper the infrastructure and the tower structure and instrumentation are described. The results of long term optical background measurements are presented. The rates show stable and low baseline values, compatible with the contribution of K-40 light emission, with a small percentage of light bursts due to bioluminescence. All these features confirm the stability and good optical properties of the site.Funded by SCOAP3Adrián Martínez, S.; Aiello, S.; Ameli, F.; Anghinolfi, M.; Ardid Ramírez, M.; Barbarino, G.; Barbarito, E.... (2016). Long term monitoring of the optical background in the Capo Passero deep-sea site with the NEMO tower prototype. European Physical Journal C: Particles and Fields. 76(68):1-11. https://doi.org/10.1140/epjc/s10052-016-3908-0S1117668M. Ageron et al., ANTARES: the first undersea neutrino telescope. Nucl. Instr. Methods A 656, 11 (2011)V. Aynutdnov for the Baikal Coll., The BAIKAL neutrino project: results and perspective. Nucl. Instr. Methods. A 628, 115 (2011)A. Achterberg et al., First year performance of the IceCube neutrino telescope. Astropart. Phys. 26, 155 (2006)M.G. Aartsen et al., Evidence for high-energy extraterrestrial neutrinos at the IceCube detector. Science 342, 1242856 (2013)M.G. Aartsen et al., Observation of high-energy astrophysical neutrinos in three years of IceCube data. Phys. Rev. Lett. 113, 101101 (2014)M.G. Aartsen et al., Evidence for astrophysical muon neutrinos from the northern sky with IceCube. Phys. Rev. Lett. 115, 081102 (2015)E. Migneco et al., Status of NEMO. Nucl. Instr. Methods A 567, 444 (2006)E. Migneco et al., Recent achievements of the NEMO project. Nucl. Instr. Methods A 588, 111 (2008)A. Capone et al., Recent results and perspectives od the NEMO project. Nucl. Instr. Methods A 602, 47 (2009)M. Taiuti et al., The NEMO project: a status report. Nucl. Instr. Methods A 626, S25 (2011)S. Aiello et al., Measurement of the atmospheric muon flux of the NEMO Phase-1 detector. Astropart. Phys. 33, 263 (2010)A. Capone et al., Measurements of light transmission in deep sea with the AC9 transmissometer. Nucl. Instr. Methods A 487, 423 (2002)G. Riccobene et al., Deep seawater inherent optical properties in the Southern Ionian Sea. Astropart. Phys. 27, 1 (2007)A. Rubino et al., Abyssal undular vortices in the Eastern Mediterranean basin. Nat. Commun. 3, 834 (2012)KM3NeT web site. www.km3net.orgM. Sedita for the NEMO collaboration, Electro-optical cable and power feeding system for the NEMO Phase-2 project. Nucl. Instr. Methods A 567, 531 (2006)R. Cocimano for the NEMO collaboration, A comparison of AC and DC power feeding systems based on the NEMO experiences. Nucl. Instr. Methods A 602, 171 (2009)A. Orlando for the NEMO collaboration, On line monitoring of the power control and engineering parameters systems of the NEMO Phase-2 tower. Nucl. Instr. Methods. A 602, 180 (2009)M. Musumeci for the NEMO collaboration, Construction and deployment issues for a km {3} 3 underwater detector. Nucl. Instr. Methods. A 567, 545 (2006)S. Aiello et al., The optical modules of the phase-2 of the NEMO project. JINST 8, P07001 (2013)E. Leonora, S. Aiello, Design and assembly of the optical modules for phase-2 of the NEMO project. Nucl. Instr. Methods A 725, 234 (2013)S. Aiello et al., Procedures and results of the measurements on large area photomultipliers for the NEMO project. Nucl. Instr. Methods A 614, 206 (2010)C.A. Nicolau for the NEMO collaboration, An FPGA-based readout electronics for neutrino telescopes. Nucl. Instr. Methods A 567, 552 (2006)M. Cordelli et al., PORFIDO: oceanographic data for neutrino telescopes. Nucl. Instr. Methods A 626–627, S109 (2011)F. Ameli, The data acquisition and transport design for NEMO Phase-1. IEEE Trans. Nucl. Sci. 55(1), 233 (2008)A. D’Amico for the NEMO collaboration, Design of the optical Raman amplifier for the shore station of NEMO Phase-2. Nucl. Instr. Methods A 626–627, S173 (2011)T. Chiarusi for the NEMO collaboration, Scalable TriDAS for the NEMO project. Nucl. Instr. Methods A 630, 107 (2011)S. 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The trigger and data acquisition for the NEMO-Phase 2 tower

In the framework of the Phase 2 of the NEMO neutrino telescope project, a tower with 32 optical modules is being operated since march 2013. A new scalable Trigger and Data Acquisition System (TriDAS) has been developed and extensively tested with the data from this tower. Adopting the all-data-to-shore concept, the NEMO TriDAS is optimized to deal with a continuous data-stream from off-shore to on-shore with a large bandwidth. The TriDAS consists of four computing layers: (i) data aggregation of isochronal hits from all optical modules; (ii) data filtering by means of concurrent trigger algorithms; (iii) composition of the filtered events into post-trigger files; (iv) persistent data storage. The TriDAS implementation is reported together with a review of dedicated on-line monitoring tools

Measurement of the atmospheric muon depth intensity relation with the NEMO Phase-2 tower

90nonemixedChiarusi T.; Aiello S.; Ameli F.; Anghinolfi M.; Barbarino G.; Barbarito E.; Barbato F.; Beverini N.; Biagi S.; Bouhadef B.; Bozza C.; Cacopardo G.; Calamai M.; Cali C.; Capone A.; Caruso F.; Ceres A.; Circella M.; Cocimano R.; Coniglione R.; Costa M.; Cuttone G.; D'Amato C.; D'Amato V.; D'Amico A.; DeBonis G.; De Luca V.; Deniskina N.; De Rosa G.; Distefano C.; Fermani P.; Flaminio V.; Fusco L. A.; Garufi F.; Giordano V.; Giovanetti G.; Gmerk A.; Grasso R.; Grella G.; Hugon C.; Imbesi M.; Kulikovsky V.; Larosa G.; Lattuada D.; Leonora E.; Litrico P.; Lonardo A.; Longhitano F.; Lo Presti D.; Maccioni E.; Margiotta A.; Martini A.; Masullo R.; Migliozzi P.; Migneco E.; Miraglia A.; Mollo C.; Mongelli M.; Morganti M.; Musico P.; Musumeci M.; Nicolau C. A.; Orlando A.; Papaleo R.; Pellegrino C.; Pellegriti M. G.; Perrina C.; Piattelli P.; Pugliatti C.; Pulvirenti S.; Raffaelli F.; Randazzo N.; Riccobene G.; Rovelli A.; Sanguineti M.; Sapienza P.; Sgura I.; Simeone F.; Sipala V.; Spurio M.; Speziale F.; Spitaleri A.; Taiuti M.; Terreni G.; Trasatti L.; Trovato A; Ventura C.; Vicini P.; Viola S.; Vivolo D.Chiarusi, T.; Aiello, S.; Ameli, F.; Anghinolfi, M.; Barbarino, G.; Barbarito, E.; Barbato, F.; Beverini, N.; Biagi, S.; Bouhadef, B.; Bozza, C.; Cacopardo, G.; Calamai, M.; Cali, C.; Capone, A.; Caruso, F.; Ceres, A.; Circella, M.; Cocimano, R.; Coniglione, R.; Costa, M.; Cuttone, G.; D'Amato, C.; D'Amato, V.; D'Amico, A.; Debonis, G.; De Luca, V.; Deniskina, N.; De Rosa, G.; Distefano, C.; Fermani, P.; Flaminio, V.; Fusco, L. A.; Garufi, F.; Giordano, V.; Giovanetti, G.; Gmerk, A.; Grasso, R.; Grella, G.; Hugon, C.; Imbesi, M.; Kulikovsky, V.; Larosa, G.; Lattuada, D.; Leonora, E.; Litrico, P.; Lonardo, A.; Longhitano, F.; Lo Presti, D.; Maccioni, E.; Margiotta, A.; Martini, A.; Masullo, R.; Migliozzi, P.; Migneco, E.; Miraglia, A.; Mollo, C.; Mongelli, M.; Morganti, M.; Musico, P.; Musumeci, M.; Nicolau, C. A.; Orlando, A.; Papaleo, R.; Pellegrino, C.; Pellegriti, M. G.; Perrina, C.; Piattelli, P.; Pugliatti, C.; Pulvirenti, S.; Raffaelli, F.; Randazzo, N.; Riccobene, G.; Rovelli, A.; Sanguineti, M.; Sapienza, P.; Sgura, I.; Simeone, F.; Sipala, V.; Spurio, M.; Speziale, F.; Spitaleri, A.; Taiuti, M.; Terreni, G.; Trasatti, L.; Trovato, A; Ventura, C.; Vicini, P.; Viola, S.; Vivolo, D

Long-term optical background measurements in the Capo Passero deep-sea site

In March 2013, the Nemo Phase-2 tower has been successfully installed at 100 km off-shore Capo Passero (Italy) and 3500 m depth. This 8-floor tower hosts 32 10-inch PMT's. Results from optical background measurements are presented. In particular, the analyzed rates show stable and low baseline values, compatible with the contribution of 40K light emission, with a small percentage of light bursts due to bioluminescence. All these features are a confirmation of the stability and good optical nature of the site

Inertial bioluminescence rhythms at the Capo Passero (KM3NeT-Italia) site, Central Mediterranean Sea

In the deep sea, the sense of time is dependent on geophysical fluctuations, such as internal tides and atmospheric-related inertial currents, rather than day-night rhythms. Deep-sea neutrino telescopes instrumented with light detecting Photo-Multiplier Tubes (PMT) can be used to describe the synchronization of bioluminescent activity of abyssopelagic organisms with hydrodynamic cycles. PMT readings at 8 different depths (from 3069 to 3349 m) of the NEMO Phase 2 prototype, deployed offshore Capo Passero (Sicily) at the KM3NeT-Italia site, were used to characterize rhythmic bioluminescence patterns in June 2013, in response to water mass movements. We found a significant (p < 0.05) 20.5 h periodicity in the bioluminescence signal, corresponding to inertial fluctuations. Waveform and Fourier analyses of PMT data and tower orientation were carried out to identify phases (i.e. the timing of peaks) by subdividing time series on the length of detected inertial periodicity. A phase overlap between rhythms and cycles suggests a mechanical stimulation of bioluminescence, as organisms carried by currents collide with the telescope infrastructure, resulting in the emission of light. A bathymetric shift in PMT phases indicated that organisms travelled in discontinuous deep-sea undular vortices consisting of chains of inertially pulsating mesoscale cyclones/anticyclones, which to date remain poorly known

Measurement of the atmospheric muon flux at 3500 m depth with the NEMO Phase-2 detector

In March 2013, the Nemo Phase-2 tower was successfully deployed at 80 km off-shore Capo Passero (Italy) at 3500 m depth. The tower operated continuously until August 2014. We present the results of the atmospheric muon analysis from the data collected in 411 days of live time. The zenith-angle distribution of atmospheric muons was measured and results compared with Monte Carlo simulations. The associated depth intensity relation was then measured and compared with previous measurements and theoretical predictions

Status and first results of the NEMO Phase-2 tower

In March 2013, the NEMO Phase 2 tower has been successfully installed in the Capo Passero site, at a depth of 3500 m and 80 km off from the southern coast of Sicily. The unfurled tower is 450 m high; it is composed of 8 mechanical floors, for a total amount of 32 PMTs and various instruments for environmental measurements. The tower positioning is achieved by an acoustic system. The tower is continuously acquiring and transmitting all the measured signals to shore. Data reduction is completely performed in the Portopalo shore station by a dedicated computing facility connected to the persistent storage system at LNS, in Catania. Results from the last 9 months of acquisition will be presented. In particular, the analyzed optical rates, showing stable and low baseline values, are compatible with the contribution mainly of 40K light emission, with a small percentage of light bursts due to bioluminescence. These features reveal the optimal nature of the Capo Passero abyssal site to host a km3 -sized Neutrino Telescope

The trigger and data acquisition for the NEMO-Phase 2 tower

In the framework of the Phase 2 of the NEMO neutrino telescope project, a tower with 32 optical modules is being operated since march 2013. A new scalable Trigger and Data Acquisition System (TriDAS) has been developed and extensively tested with the data from this tower. Adopting the all-data-to-shore concept, the NEMO TriDAS is optimized to deal with a continuous data-stream from off-shore to on-shore with a large bandwidth. The TriDAS consists of four computing layers: (i) data aggregation of isochronal hits from all optical modules; (ii) data filtering by means of concurrent trigger algorithms; (iii) composition of the filtered events into post-trigger files; (iv) persistent data storage. The TriDAS implementation is reported together with a review of dedicated on-line monitoring tools

Inertial bioluminescence rhythms at the Capo Passero (KM3NeT-Italia) site, Central Mediterranean Sea

In the deep sea, the sense of time is dependent on geophysical fluctuations, such as internal tides and atmospheric-related inertial currents, rather than day-night rhythms. Deep-sea neutrino telescopes instrumented with light detecting Photo-Multiplier Tubes (PMT) can be used to describe the synchronization of bioluminescent activity of abyssopelagic organisms with hydrodynamic cycles. PMT readings at 8 different depths (from 3069 to 3349 m) of the NEMO Phase 2 prototype, deployed offshore Capo Passero (Sicily) at the KM3NeT-Italia site, were used to characterize rhythmic bioluminescence patterns in June 2013, in response to water mass movements. We found a significant (p &lt; 0.05) 20.5 h periodicity in the bioluminescence signal, corresponding to inertial fluctuations. Waveform and Fourier analyses of PMT data and tower orientation were carried out to identify phases (i.e. the timing of peaks) by subdividing time series on the length of detected inertial periodicity. A phase overlap between rhythms and cycles suggests a mechanical stimulation of bioluminescence, as organisms carried by currents collide with the telescope infrastructure, resulting in the emission of light. A bathymetric shift in PMT phases indicated that organisms travelled in discontinuous deep-sea undular vortices consisting of chains of inertially pulsating mesoscale cyclones/anticyclones, which to date remain poorly known