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Annual Report 2009 P O R T A LNGS/EXP-01/10 N May 2010 N U A L R E Annual Report 2009 P O R T 2 0 0 9 Lab ora tor i N o az s io as nal S i del Gran LNGS - s.s. 17 bis km 18,910 67010 ASSERGI (AQ) ITALY tel.+39 0862 4371 fax +39 0862 437559 email: [email protected] http://www.lngs.infn.it Codice ISBN ISBN-978-88-907304-5-0 Annual Report 2009 LNGS Director Dr. Lucia Votano Editor Dr. Roberta Antolini Technical Assistants Dr. Adriano Di Giovanni Marco Galeota The Gran Sasso National Laboratory My mandate as Director at LNGS took effect from September 2009 and it would be unthinkable to start this introduction to the 2009 LNGS annual report without mentioning the earthquake of last April which left 370 people dead, 15,000 injured and devastated the surrounding area together with the social and economic life of L’Aquila. Most of the lab personnel as well as the 70,000 inhabitants in L’Aquila were rendered homeless. Fortunately the Laboratory survived the devastating earthquake and escaped damage. This was possible thanks to two factors: the acceleration experienced deep underground, (0.03g), as expected, was lower than that of the external laboratory (0.15 g) and much lower than in L’Aquila (0.64 g).; the anti-seismic design of the apparatus protected the underground installations. In April Eugenio Coccia was still on duty as Director of the Lab, and I think it is proper to mention how effective his dedication and actions were, in providing support to the laboratory personnel and assuring the immediate restarting of the activities in the Laboratory. From April 6th access to the laboratory was limited, a series of inspections by LNGS staff, Engineers from the Department of Civil Protection, experts on structures, geology and hydro- geology resulted on April 24th in the Laboratory being granted certification of safe use and occupancy. Thanks to the dedication of the Lab staff who, despite their quite serious personal difficulties, immediately after the earthquake worked toward the safe operation of the laboratory, on May 4th access and the normal operation of all the experiments resumed. The INFN management has also strongly contributed to the setting up of a plan of support: hosting the homeless people in hotels, guest houses and trailers inside the lab area; making donations for immediate needs; refunding travel expenses to and from the new accommodation (mainly on the Adriatic coast) and the Lab. The general situation is now slowly improving and the new challenge is more ambitious, that of contributing to the rebirth of the L’Aquila community. The Laboratory has a significant role in the life of the town: if we preserve this feature of excellence, our international research activities will offer hope of renewal of the cultural, social and economic life of L’Aquila. We are also trying to stimulate new initiatives such as allowing the Municipality to set up a school in our external area, hosting meetings, and intensifying relationships with the local Institutions. For example we are involved in setting up a new interactive science museum in a park in the heart of the ruined medieval center of L’Aquila. Despite the troubles and discomfort connected to the earthquake, from a scientific point of view, 2009 was an auspicious year. It marked the thirtieth anniversary of the official birth of the Gran Sasso Laboratory project and the twentieth anniversary of the first experimental data published by the MACRO experiment. The scientific legacy I inherited is definitely impressive and my first duty is to ensure the laboratories maintain their worldwide leadership in astroparticle physics. The Gran Sasso National Laboratory of INFN is a research infrastructure devoted to astroparticle physics It has no equal elsewhere and offers the most advanced underground Laboratory in terms of dimensions, complexity and completeness of the infrastructure. Located between L’Aquila and Teramo, about 120 km from Rome, the underground structures are on one side of the highway tunnel (10 km long) which crosses the Gran Sasso massif, towards Rome, and consist of three huge experimental halls, (each one 100 m long, 20 m large and 18 m high) and a bypass tunnel, for a total volume of about 180.000 m3 and a surface of 18.000 m2. The halls are equipped with all the technical and safety equipment and apparatus necessary for the experimental activities at the same time as ensuring proper working conditions for the people involved. The 1400 m. of rock overhead provide a cover which is able to reduce the cosmic rays flux by a million times; moreover, the flux of neutrons in the underground halls is about thousand times less than on the surface due to the very small amount of Uranium and Thorium of the Dolomite calcareous rock of the mountain. The permeability of cosmic radiation provided by the rock coverage, the huge dimensions and the impressive basic infrastructure, make the Laboratory absolutely unique for the detection of weak or rare signals, relevant for astroparticle, sub nuclear and nuclear physics. On the outside, near the Assergi tollgate on the highway A24, an area of more than 23 acres belonging to a National Park of exceptional environmental and naturalistic interest on the slopes of Gran Sasso, hosts the laboratories of chemistry, electronic, mechanical, design and workshops, the Computing Centre, the Directorate and the various Offices. The high international status enjoyed by the LNGS is reflected in the large number of publications to come out of its work , and in the fact that about 950 scientists take part in its research. Half of them come from 29 different countries. At present we have fifteen experiments in different phases of realization. The study of the intrinsic properties of neutrino is of prime interest in particle physics and one of the main research topics of the present scientific program of the Laboratory. In order to properly comprehend the mechanism of neutrino oscillation, it is necessary to measure the elements of the mixing matrix by means of various neutrino sources, both natural (the Sun or other Stars) and artificial (particle accelerators). Besides, the study of the phenomenon of neutrinoless double beta decay could allow us to find out if the neutrino overlaps with its antiparticle, thus providing a very significant answer towards the comprehension of the evolution of the Universe. Neutrino physics therefore offers a window to a new theory of elementary particles and to the comprehension of the evolution of the Universe. Finally, neutrinos from the cosmos are very important messengers which transport information fundamental to our understanding of the functioning of the stars as energy sources, their evolution and what happens when they “turn off”. LNGS activities range among various aspects of the neutrino physics’ study. The measurement of neutrino oscillations in appearance mode is the main goal of OPERA experiment, which aims to the detection of tau neutrinos in the artificial neutrino beam from CERN to Gran Sasso (CNGS), originally constituted by muon neutrinos only. Throughout 2009 Opera has collected 3700 events on target in addition to the 1689 events collected in 2008. By now 19 charmed events have been identified in 2008 data, showing that the experiment is capable of detecting events with topologies very similar to τ production. The expected number of ντ for the entire statistics collected up to now is about 2. Another experiment able to detect CNGS beam will be ICARUS, an innovative apparatus consisting of a big mass (about 600 tons) of liquid Argon, allowing a 3D imaging of any interactions of charged particles inside its volume. ICARUS is in the phase of commissioning and expected to be filled with argon in spring 2010. Borexino measures in real-time the interactions of solar neutrinos flux by means of a 300 ton sphere of scintillating liquid. This allows us to study the functioning of the Sun and at the same time neutrino properties. Throughout 2009 a calibration campaign has led to a strong reduction of the systematic errors of the 7Be neutrino flux measurement. The contemporary measurement of the 7Be and the 8B neutrino flux will grant a determination in the same experiment of the ratio vacuum/matter of the oscillation parameters. The search for terrestrial antineutrino interactions has become a hot point of the data analysis. The LVD experiment is continuously monitoring the Galaxy with its 1000 tons of liquid scintillator, looking for collapsing stars and it also offers an original monitoring of the CNGS neutrino beam. LVD participates in the SuperNovae Early Warning System of detectors. The study of neutrino properties through the research into a rare process called ‘neutrinoless double beta decay’ may give a direct indication as to the value of its mass ascertaining its nature of Majorana particles (that is particle and antiparticle coinciding). At present LNGS is host to several experiments devoted to research neutrinoless double beta decay events. The experiment GERDA will use the same enriched Germanium crystals of the Heidelberg- Moscow experiment, but they will be directly immersed in 60 m3 of liquid Argon, which is a first protection from cosmic radiation. A 10 m diameter tank built all around the cryostat is a further protection and acts as a veto Cerenkov for muons. Once the installation of the apparatus had been completed in 2009 the cryostat was successfully filled with Argon and, after final checks currently ongoing, the external shield will be filled with water. The experiment CUORE, after the success of CUORICINO, is the most recent and ambitious development of the ‘TeO2 bolometers’ technique, in which INFN has more than 20 years experience.
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