The Gran Sasso National Laboratories are the most advanced underground laboratories in the world. They are excavated under 1400 meters of rock inside the Gran Sasso Mountain, and only a small percentage of particles can penetrate such an isolated environment: in particular neutrinos, very few charged particles and, possibly, dark matter particles. At the moment at Laboratories are under construction experimental apparata aimed to detect the beam of neutrinos that will be produced at Cern in Geneva and directed to Gran Sasso. The goal is to study the oscillation of these particles that causes three different types of neutrinos to mix and to transform one into another. The full comprehension of the neutrinos behaviour is of primary importance in order to understand the fundamental structure of matter and thus the functioning of stars and in particular of our Sun.
The extremely high scientific value of the research at Gran Sasso Labs has always been globally recognized and the present difficult moment, started August 16th 2002, is worrying the international scientific community. That day a leaking of 50 litres of pseudocumene (a mineral oil derived from petrol and used to detect neutrinos) has occurred during the preparation of the Borexino experiment, dedicated to the study of solar neutrinos. No damage was caused but the potential damage was enough to raise alarm among the citizens. For this reason in October 2002 the prosecuting magistrate of Teramo has established the preventive sequestration of the Borexino experiment, subsequently extended to the entire hall where it has been placed (Hall C).
On June 2003, due to information which threw strong doubts upon the water-tightness of the draining system of the Gran Sasso Laboratories, Infn decided as a precaution to suspend any activity implying manipulation of any kind of liquid. At the same time, the Institute has asked for an immediate intervention of the competent government authorities in order to put the Labs in condition to work.
On June 17th the Competent Court of Teramo has partially accepted the requests of Infn, allowing the restart of some scientific activities within the underground Hall C. In particular, the preparation of the Opera experiment could start again. Opera and Icarus experiments will study the neutrino beam from Cern. This decision recognizes the crucial role of the present and future research in preparation at Gran Sasso and, jointly with the decree of the President of the Council of Ministers established on June 27th, preludes a restart of the research activities in a condition that assures complete safety for Abruzzo citizens and a deep confidence between them and the Labs.