BOREXINO

Collaboration:

- Italy: Università e INFN di Genova, Milano, Pavia, Perugia and LNGS
- Belgium: I.R.M.M. European Joint Research Center - Geel
- Canada: Queen's University - Kingston
- France: College de France - Paris
- Germany: Max-Planck-Institut fuer Kernphysik Heidelberg, Technische Universitaet Muenchen
- Hungary: KFKI-RMKI Research Institute for Particle & Nuclear Physics Budapest
- Poland: Institute of Physics, Jagellonian University, Cracow
- Russia: J.I.N.R. DUBNA, Kurchatov Institute - Moscow
- USA: Bell Laboratories - Lucent Technologies, Massachusetts Institute of Technology, Princeton University, Virginia Polytechnic Institute

Location of the experiment: Laboratorio Nazionale del Gran Sasso (LNGS)

National Responsible: G. Bellini (Mi)

1. Goal of the experiment

Borexino, a solar neutrino real time experiment at LNGS, makes use of the neutrino-electron scattering reaction to detect neutrinos emitted from the Sun. It is the only experiment in real time planned for the next few years, having a threshold below 1 MeV.

In Borexino is mainly interested in the observation of the 7Be neutrinos, which is a monochromatic line at 863 keV.

More on the experiment…

2.

Activities during 2002

The major accomplishment in the year 2002 consisted in the construction and arrival of the inner vessel, the procurement and the delivery of the Inner Vessel scintillator inventory and the completion of the Fluid Handling system. Moreover radiopurity testing with the CTF was continued.

In addition the DAQ, electronics, online monitor and calibration system were studied by means of several dedicated "air runs". The Data Base for online and offline, and the offline reconstruction program have been tested and implemented.

The following achievements have been obtained:

- Completion of scintillator testing with CTF (50%(*))
- Scintillator (PC) trasportation for the inner vessel (100%)
- Water filling of the external tank.(**)
- Buffer PC procurement and Borexino filling(**)
- DAQ, online monitor, electronics testing (90%)

(*) Scintillator tests are still in progress. In particular, distillation of the PC has still to be tested.

(**) The water filling and the Buffer PC procurement are delayed due to work in progress for the Inner Vessel and purification plants.

Milestones 2003

Completion of the work in the SSS | 30-05-2003
End of water filling | 31-08-2003
End of calibration with water in the detector | 15-11-2003
CTF test completion (depending on external conditions) |
Start of Pc procurement and filling (depending on external conditions) |

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

Manpower: 51 researchers (35.6 FTE), 9 technicians (6.9 FTE)

Budget for the year 2003: 6.0% of the total CSNII budget

4. Number of publications in refereed journals (in 2002): 3

5. Number of talks to conferences (in 2002): 6

6. Number of undergraduate and doctoral thesis on the experiment:

- n. 2 Laurea Diplomas

7. Leadership roles and primary responsibilities of the experiment

- G. Bellini(Mi) is the spokesman of the experiment.
- G. Manuzio (Ge) is a member of the Executive Committee.
- G. Ranucci (Mi) is the Project Manager

Several physicists of the Italian part of the collaboration are responsible of some of the main subsystems and plants of the experiment:

- M. Giammarchi - water purification and PC procurement;
- G. Ranucci – PMT’s;
- M. Pallavicini - Electronics, Daq;
- D. Giugni - Engineering;
- R. Tartaglia - Site manager,
- S. Malvezzi – Calibrations;
- E. Meroni – Software;
- G. Testera - Scintillator

8. Innovative instruments

The Counting Test Facility has been demonstrated to be one of the lowest background facilities in the World.

The collaboration has developed measurement techniques for radioassay of constructing materials, water, and nitrogen at unprecedented sensitivity levels.

The liquid scintillator purification and the associated radioactivity measurements represent a record in this field.

9.Competing experiments

Kamland, after a first measurement phase for reactor antineutrinos, that aims to explore the LMA solution at larger mass, could be upgraded to attempt the 7Be measurement.

10. International committee which has reviewed the experiment

The experiment is continuously reviewed by the Committee II of INFN, by the NSF, by the German funding agencies, and by the International Scientific Committee of the Gran Sasso Laboratory.