NEMO-RD
Collaboration
National Responsible: E. Migneco (LNS)
1. Goal of the experiment
The realization of a telescope for high-energy neutrinos
of astrophysical origin is nowadays considered as one of the most important aims
in the astroparticle physics field. The detection of these neutrinos could help
to investigate the mechanisms giving 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 from atmospheric cosmic rays.
The most promising technique seems to be the detection of the Cherenkov light
emitted by secondary muons produced in 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 realization of such a detector. In particular the issues addressed are:
2.
Activities during 2002
During 2002
the collaboration has continued the characterization of the deep-sea site close
to Capo Passero, selected as a candidate site for the installation of the km3
neutrino detector. Measurements of optical properties, water currents,
sedimentation, optical background and biofouling have been carried out. As
planned an extensive number of sea campaigns has allowed measuring optical water
properties in different periods of the year, establishing the seasonal
dependence of these parameters. Deep-sea optical properties have been found to
be stable throughout the year, confirming the excellent characteristics of the
site. During 2002 two sea campaigns, one on the Capo Passero site and one on the
Toulon site where the Antares detector will be installed, have been carried out
in collaboration with the Antares site exploration group. During these campaigns
instruments developed by both the NEMO and Antares collaborations have been used
jointly, allowing a cross check of the results. In particular the absorption
length has been measured with the NEMO AC9 transmissometer and the Antares Test
3 setup. Results are in agreement showing that the absorption length in the blue
region of the spectrum is 68 m in Capo Passero and 48 m in Toulon. Optical
background has also been measured with two similar setups, one developed by the
NEMO collaboration and one by Antares. With these setups the background due to
the presence of 40K in seawater and to bioluminescence has been
measured, showing that the background rate is more than a factor of 2 lower in
Capo Passero (28 kHz on a 8 PMT, compatible with the unavoidable 40K
background) than in Toulon (58 kHz, with a strong presence of bioluminescence).
A project
for the realization of an undersea installation to be realized at the Catania
LNS underwater Test Site has been developed. This project, called NEMO Phase 1,
comprises all the essential components (junction boxes, flexible towers,
electronics and data transmission system, cable interconnections,
) of the km3
detector, as defined by the preliminary project developed by the collaboration,
and aims at demonstrating the technological feasibility of the detector. This
project, which is partially supported by the INFN, is also funded for an amount
of 3 MEuro by the MIUR through a contract approved in November 2002. A further
request of funding, for approximately 2 MEuro, has been submitted to the MIUR in
January 2003.
The following achievements have been obtained:
(*)
an extensive number of sea campaigns has been performed on the Capo Passero
site, allowing for a study of the seasonal dependence of the optical properties
of the waters. However, it is foreseen to extend the data collection for the
forthcoming years to allow for a long term characterization of the site.
(**)
a first prototype is ready and assembled; realization of the firmware is in
progress.
(***)
design of the structure completed; start of the realization postponed due
to delayed funding; the realization is in progress and completion foreseen by
june 2003.
Milestones 2003
Realization and test in water of a 1/10 scale model of the tower | 30-04-2003 |
Realization of the prototype of the power and front-end electronics contained inside the Optical Module | 31-05-2003 |
Realization of a prototype of a tower storey | 30-06-2003 |
Realization of a prototype of the storey electronics | 30-09-2003 |
Realization of prototypes of the Optical Modules | 30-09-2003 |
Realization of an assembly tool for the Optical Modules (subject to the approval of a further funding request during next year - date to be defined) | to be defined |
Realization of a prototype of the Junction Box (subject to the approval of a further funding request during next year - date to be defined) | to be defined |
3. INFN contribution to the experiment in terms of manpower and financial support
Manpower:
The INFN participation in the experiment amounts to 58 physicists and engineers for a total of 23.5 FTE and 15 technicians (5.1 FTE). Support is also given from the mechanics and electronics workshops of the INFNs "Sezioni" and Laboratori that are involved in the project.
Budget for the Year 2003: 1.7 % of the CSN2 budget for 2003.
4. Number of publications in refereed journals: 1
5. Conferences talks: 2
5 talks, 2 of which invited.
6. Number of undergraduate and doctoral thesis on the experiment
7. Leadership roles in the experiment
8. Innovative instruments
The in situ
measure of the water optical properties is crucial for the characterization 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 realized an instrument to measure the angular
distribution of the scattered light at different wavelengths. This scatter-meter
(called DEWAS) has been successfully tested in deep water (3400 m) and is now
undergoing the laboratory calibrations. A study to upgrade the system
sensitivity is also under way.
An
instrument to measure the attenuation length of light in water has also been
designed and tested in shallow waters.
9. Competing experiments
The goal of building a 1 km3 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, is also invlved 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 1 km3 dimensions. AMANDA, the second running experiment located in the South Pole ice, is planning to reach the 1 km2 effective area (project ICE-CUBE); this experiment is at only 2000 m 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.
The
Peer Review Committee of ApPEC will give an evaluation of the properties of the
proposed sites for the neutrino telescope.