NEMO-RD

Collaboration

- INFN: Bari, Bologna, Cagliari, Catania, Genova, LNF-Laboratori Nazionali di Frascati, LNS-Laboratori Nazionali del Sud, Messina, Roma 1
- OGS Trieste
- CNR: IOF, La Spezia; IBM, Venezia; Ist. Talassografico, Messina.

National Responsible: E. Migneco (LNS)

Web page: http://nemoweb.lns.infn.it/

1. Goal of the experiment

The realisation of a telescope for high energy neutrinos of astrophysical origin is considered nowadays one of the most important aims in the astroparticle physics field. The detection of these neutrinos could help to investigate the mechanisms that give rise to the most energetic phenomena in the Universe such as the Active Galactic Nuclei and the Gamma Ray Bursts. It is believed that such a detector must have an active volume of 1 km3 and should be shielded by atmospheric cosmic rays. The most promising technique seems to be the detection of the Cherenkov light emitted by the secondary muons produced by neutrino interaction by means of an array of detectors located in the sea abysses at a depth of more than 3000 m.

The experimental program of NEMO-RD is to develop technologies suitable for the realisation of such a detector. In particular the issues addressed are:

- study of optical and oceanographic properties of deep sea waters aimed at finding and characterize a candidate site (close to the Italian coast) for the detector installation;
- development of new low-power electronics suitable for the submarine environment
- study of the mechanical feasibility of the detector

2.

Activities during 2001

During 2001 the collaboration has continued the characterization of the deep sea site close to Capo Passero. Measures of of optical properties, water currents, sedimentation, optical background and biofouling have been carried out. Although a complete characterization of the site deserves the monitoring of these properties over at least a whole seasonal cicle (this objective will be reached with the oceanographical campaigns planned for 2002) the results obtained so far have established that the site fulfills all the requests needed for the installation of the underwater neutrino detector.

The feasibility study, conducted together with a consortium of firms with proven experience in marine operations, has been completed. This study has lead to the definition of a preliminary project of the detector in which all the relevant technological issues have been addressed, showing that technical solutions are presently available to realize the project at a reasonable cost.

The milestones that were expected to be achieved in 2001 were:

- Continuation of the data collection in Capo Passero — (Status at 31-12-2001: 100%);
- Realization of 16 DAQ channels with HV, low power front end electronics, data transmission and trigger - (Status at 31-12-2001: 80%) design completed, realization is under way;
- Prototype of a slow control module — (Status at 31-12-2001: 100%) a first prototype has been realized for the NERONE attenuation metre and testd in water in november 2001.

Milestones 2002

Completion of data collection at the Capo Passero Site | 31-12-2002
Realization of a prototype of the mechanical structure for a "flexible tower" | 31-12-2002
Realization of the storey electronics and data transmission system | 31-12-2002

3. INFN contribution to the experiment in terms of manpower and financial support

Manpower:

The INFN participation in the experiment amounts to 49 physicists and engineers for a total of 16.3 FTE. Support is also given from the mechanics and electronics workshops of the INFN’s "Sezioni" and Laboratori that are involved in the project.

Budget for the Year 2002: 177 kEuro

4. Number of publications in refereed journals

5. Conferences talks:

5 talks, 2 of which invited.

6. Number of undergraduate and doctoral thesis on the experiment

- Undergraduate theses (in progress) 3
- Undergraduate theses (completed in 2001) 6
- PhD theses (in progress) 1
- PhD theses (completed in 2001) 1

7. Leadership roles in the experiment

- E. Migneco — Spokesman

8. Innovative instruments

The in situ measure of the water optical properties is crucial for the characterisation of the deep sea site. Some of these properties, like the volume scattering function, have never been measured in situ before. To achieve this result the collaboration has designed and realised an instrument to measure the angular distribution of the scattered light at different wavelengths. This scatter-metre (called DEWAS) has been successfully tested in deep water (3400 m) in october 2001.

An instrument to measure the attenuation length of light in water has also been designed and tested in shallow waters. After some mechanical modifications it will be ready for use in deep waters in 2002.

Both these new instruments could find applications in marine biology and oceanographic researches.

9. Competing experiments

The goal of building a 1km3 neutrino telescope and the related R&D activities are followed with interest by two other collaborations in the Mediterranean (NESTOR and ANTARES) planning to deploy a detector with lower effective area (demonstrator). An Italian collaboration, including physicists from the NEMO collaboration, also takes place in the ANTARES experiment.

Baikal, one of the two astrophysics neutrino experiments at present in data taking, is limited by the shallowness of the detector and will not achieve the 1km3 dimensions. AMANDA, the second running experiment located in the South Pole ice, is planning to reach the 1 km2 effective area (project ICE-CUBE): also this experiment is at only 2000m depth and is limited by light scattering in ice.

10. International committee which has reviewed the experiment

The experiment is reviewed by the funding authorities of INFN "Commissione II".