Last Update: October 2000

NEMO

Collaboration

INFN Bari (R. Bellotti, F. Cafagna, F. Ciacio, M. Circella, C. De Marzo, T. Montaruli)

INFN Bologna (E. Gandolfi, A. Gabrielli, D. Falchieri, M. Masetti, G. Zanarini)

INFN Cagliari (R. Habel, I.Usai)

INFN Catania (S. Aiello, G. Andronico, F. Burgio, G. Burrafato, L. Caponnetto, D. Lo Presti, L. Pappalardo, C. Petta, N. Randazzo, G.V. Russo, M. Russo, O. Troia)

INFN Messina (R. Barnà, V. D’Amico, E. De Domenico, D. De Pasquale, A. Italiano, S. Salvato, A. Trifirò, M. Trimarchi)

INFN Roma 1 (M. Bonori, A. Capone, F. Massa, E. Salusti)

INFN LNF, Frascati (M. Cordelli, L. Trasatti, V. Valente)

INFN LNS, Catania (R. Coniglione, P. Finocchiaro, E. Migneco, P. Piattelli, G. Riccobene, P. Sapienza)

OGS Trieste (E. Accerboni, R. Mosetti, L. Ursella)

IOF CNR, La Spezia (M. Astraldi, G.P. Gasparini)

IBM CNR, Venezia (A. Boldrin)

Ist. Talassografico CNR, Messina (F. Decembrini, M. Leonardi)

1. Goal of the experiment

The experimental program is the R&D aimed at the realization of a underwater Cherenkov detector for high energy (>1 TeV) neutrinos of astrophysical origin. It is believed that such a detector must have an active volume of the order of 1 km3 and should be shielded by atmospheric cosmic rays.

The activity is divided between INFN Scientific Commissions II and V; this report presents a comprehensive summary of the activity.

The R&D issues addressed by the experiment 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
- development of the software codes for simulations of the NEMO capabilities for neutrino astronomy

2. Physics achievements during 2000

The collaboration has carried out the study of deep sea sites. Four sites have been studied in term of optical properties of water (light attenuation and absorption). During 2000 the activity has been directed at the complete characterisation of a site close to Capo Passero at a depth of 3400 m, where long term studies of oceanographic and optical parameters are under way.

An underwater experiment with about 10000 PMTs requires the development of specific low power electronics. This task has also been undertaken with the design and realization of specific ASICs which are presently under test.

The study of the mechanical feasibility of the detector is an advanced state: the first phase of activity, the conceptual design phase, has been completed. During this phase different possible configurations of the apparatus have been sketched and then compared in terms of costs, performance and reliability. A tower configuration of the detector appears as the most promising solution. The second phase of activity, the general design phase, is currently underway and will provide a general design of NEMO together with an estimate of the cost of its implementation. The final results of this study are expected shortly.

A "fast" simulation code, based on parameterisation of the Cherenkov light yield rather than on a full Monte Carlo approach, is already available and has provided valuable aid to the general design of the NEMO telescope. A full simulation code, which makes a full description of the main interactions and light production mechanisms in water, has been completed and is currently being optimised.

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

The INFN participation in the experiment amounts to 46 physicists for a total of 25.1 FTE (8.4 FTE in Gruppo II and 16.7 in Group V). Support is also given from the mechanics and electronics workshops of the INFN’s "Sezioni" and Laboratori that are involved in the project.

The total financial support from INFN in 1999 and 2000 amounts to 1836 Mlit (646 Mlit from Gruppo II and 1190 from Gruppo V), of which 658 Mlit in 2000 (269 in Gruppo II and 389 in Gruppo V).

4. Number of publications in referred journals

5. Number of talks to conferences: 8 (2 invited)

6. Number of undergraduate and doctoral thesis on the experiment

- Laurea theses (in progress) 9
- Laurea theses (completed) 4
- PhD theses (in progress)
- PhD theses (completed) 3

7. Leadership role in the experiment

- E. Migneco — Spokesman
- C. De Marzo — Coordinator of study on mechanical structure
- V. Valente - Coordinator of physics study and simulation groups
- A. Capone - Coordinator of site selection group (funds from INFN group V)
- V. Russo - Coordinator of electronics development group (funds from INFN group V)

8. Innovative instruments

The collaboration has developed instruments to measure in situ optical properties of water. A light attenuation metre and a scattering-metre could be used in marine biology and oceanographic researches.

9. Competing experiments

The goal is the 1km3 neutrino telescope project and the R&D progresses are followed with interest by two collaborations in the Mediterranean (NESTOR and ANTARES) planning to deploy a detector with lower effective area (demonstrator). NEMO and ANTARES joined recently.

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" and "Commissione V"