NEMO Phase-1 Research Articles

The NEMO project: A status report

The latest results and the activities towards the construction of a km 3 Cherenkov neutrino detector carried out by the NEMO Collaboration are described. Long-term exploration of a 3500 m deep-sea site close to the Sicilian coast has shown that it is optimal for the installation of the detector. The NEMO Phase-1 project has validated several technologies proposed for the construction of the km 3 detector on a test site at 2000 m depth. The new infrastructure on the candidate Capo Passero site set up as part of the Phase-2 project will provide the possibility to test detector components at 3500 m depth.

Measurement of the atmospheric muon flux with the NEMO Phase-1 detector

The NEMO Collaboration installed and operated an underwater detector including prototypes of the critical elements of a possible underwater km 3 neutrino telescope: a four-floor tower (called Mini-Tower) and a Junction Box. The detector was developed to test some of the main systems of the km 3 detector, including the data transmission, the power distribution, the timing calibration and the acoustic positioning systems as well as to verify the capabilities of a single tridimensional detection structure to reconstruct muon tracks. We present results of the analysis of the data collected with the NEMO Mini-Tower. The position of photomultiplier tubes (PMTs) is determined through the acoustic position system. Signals detected with PMTs are used to reconstruct the tracks of atmospheric muons. The angular distribution of atmospheric muons was measured and results compared to Monte Carlo simulations.

Status of NEMO: results from the NEMO Phase-1 detector

The NEMO Collaboration installed an underwater detector including most of the critical elements of a possible km$^3$ neutrino telescope: a four-floor tower (called Mini-Tower) and a Junction Box, including the data transmission, the power distribution, the timing calibration and the acoustic positioning systems. These technical solutions will be evaluated, among others proposed for the construction of the km$^3$ detector, within the KM3NeT Consortium. The main test of this test experiment was the validation of the proposed design solutions mentioned above. We present results of the analysis of data collected with the NEMO Mini-Tower. The position of PMTs is determined through the acoustic position system; signals detected with PMTs are used to reconstruct the tracks of atmospheric muons. The angular distribution of atmospheric muons was measured and results were compared with Monte Carlo simulations.

The electro-optical cabling system for the NEMO Phase-2 tower

The cable system layout for the NEMO Phase-2 project has been studied starting from the experience obtained after NEMO Phase-1 deployment. The aim has been to improve the reliability and simplify the integration procedures of the system. This has been attained by reducing the number of optical fibers in the backbone and by an improved layout of the optical links in the cabling. Moreover, an optimization in order to reduce the cost, in view of a large scale industrial production, has been performed. The design characteristics of the cabling system proposed for the detector line are presented.

First results from the NEMO Phase-1 experiment

The NEMO prototype detector, called “NEMO Phase-1”, has been successfully operated at 2000 m depth from December 2006 to May 2007. The apparatus comprises a Junction Box and a Mini-Tower hosting 16 optical sensors. Preliminary results are presented. Positions of the optical sensors in the Mini-Tower were reconstructed through the acoustic positioning system with a high level accuracy. Environmental parameters were analyzed. From data corresponding to a live time of 11.3 h, atmospheric muon tracks have been reconstructed and their angular distributions were measured and compared with Monte Carlo simulations.

The NEMO project: achievements and perspectives

The NEMO R&D activities towards an underwater km3 Cherenkov neutrino telescope are described. These activities include a long-term survey of a 3500 m deep site, located 80 km off the coast of Capo Passero in Sicily, that shows oceanographic and water properties that are optimal for the installation of the detector. A complete feasibility study was carried out and a preliminary design for an underwater km3 detector was performed on the basis of Monte Carlo simulations aimed at the optimization of the detector performance. The NEMO Phase-1 ended with the successful installation at an underwater test site at 2000 m depth of a technological demonstrator. Moreover, the realization of an infrastructure at the Capo Passero site (3500 m depth) is ongoing.

Status of the NEMO experiment

The activities towards the realisation of a km 3 Cherenkov underwater neutrino detector, carried out by the NEMO collaboration are described. The validation of the proposed technical solutions (NEMO Phase-1) and a detailed study of the candidate site have been undertaken (NEMO Phase-2).

Analysis of the cable system layout for the NEMO underwater detector

A general cable system layout for the NEMO project was studied and the design of all the main components of the detector was realized. The aim was to design a reasonable cost and high reliability system having the required performances. According to the R&D philosophy of NEMO Phase-1, the NEMO collaboration proposes an alternative to the standard design of housings operating in seawater environment for a long lifetime, de-coupling the pressure problem from the corrosion problem. The design characteristics of the cabling system proposed for the detector are presented.

The NEMO Phase-1 power and control systems: Status and test results

The NEMO Collaboration is conducting an intense activity to develop, apply and test technical solutions for an underwater laboratory. In this framework, the design, realization and test of NEMO Phase-1 electrical power system and power control system have been carried out. Both these systems are described with a special focus on the long-term high-pressure tests that have been carried out on the electric and electronic devices.

THE NEMO PROJECT

Since 1998 the NEMO Collaboration started a long term activity to select and characterize an optimal deep-sea site for the installation of a km3 neutrino telescope. In more than 20 sea campaigns, the water and oceanographic properties have been studied. Moreover, an intense program has been performed to study the technical feasibility of a km3 detector and many computer simulations have been made to define a suitable detector architecture. Recently the project NEMO Phase-1 has been funded by INFN and MIUR. It foresees the realization of an underwater laboratory with 3 junction boxes and a couple of instrumented towers according to the design proposed by the NEMO collaboration. The project should be completed by 2006.