Laboratori Nazionali del Gran Sasso
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The Laboratori Nazionali del Gran Sasso (LNGS) are the largest underground test laboratories in the world for the study of elementary particles and are located in the Gran Sasso d'Italia near L'Aquila . They consist of three large research halls (each 100 meters long, 20 meters wide and 18 meters high) and a bypass tunnel with a total volume of around 180,000 m³. They belong to the Istituto Nazionale di Fisica Nucleare (INFN). The halls are located along the Gran Sasso tunnel , which is also used for ground level access. They are shielded from disturbing cosmic rays by 1400 m of rock from the Abruzzo Apennines above . The management of the laboratory, offices, other laboratory rooms, workshops and the data center are housed on an area of several hectares outside the tunnel in the national park on the slopes of Gran Sasso. Around 1000 scientists from over 30 countries are currently participating in the experimental activities of the LNGS and the Gran Sasso Science Institute .
Experiments
OPERA
From August 2006 to December 2012 sent CERN a CNGS said beam of muon - neutrinos toward the 730 km distant LNGS. There, the largest detector in the LNGS, OPERA (Oscillation Project with Emulsion-tRacking Apparatus), should provide direct detection of τ -neutrinos and thus provide the last missing piece of the puzzle in the riddle of neutrino oscillations . Evidence of τ-neutrinos was carried out in an approximately 1,300-ton lead - emulsion -target. Electronic detectors were used for the real-time reconstruction of charged particles and as triggers. OPERA is around 20 m long, 10 m wide and 10 m high and weighs almost 5000 t including the surrounding structure. In September 2011, measured values obtained with the help of the OPERA detector were published, which indicated that the CERN neutrinos are moving faster than light (see “OPERA neutrino anomaly” ). However, data from the ICARUS group showed that these measured values were incorrect (see “ICARUS (2012)” ). The experiment is to be repeated in the USA at the Fermilab .
ICARUS
The ICARUS (Imaging Cosmic And Rare Underground Signals) experiment uses a liquid argon (LAr) detector to study the neutrinos of the CNGS beam. The detector is filled with 760 tons of liquid argon.
BOREXINO
BOREXINO was designed for the detection of low and medium-energy solar neutrinos. The neutrinos are detected by neutrino-electron scattering in a 300 t unsegmented liquid scintillator. BOREXINO has been collecting data since May 2007. For the first time, BOREXINO was able to directly detect solar neutrinos from the capture of electrons in 7 Be . The picture of the neutrino oscillations could be confirmed. Since 2008 data on 8 B neutrinos have also been published. BOREXINO is the first experiment that has measured both of the sun's neutrino sources. In the future, BOREXINO will provide important data on thermonuclear fusion processes in the center of the sun.
LVD
The LVD experiment (Large Volume Detector) is used to measure neutrinos from stellar outbursts in the Milky Way or Magellanic Clouds, or to study other astrophysical phenomena.
MACRO
Since 1989 the MACRO experiment has been used to detect neutrinos from supernovae in real time. It was originally designed to search for magnetic monopoles and has a segmented target made of 550 t of liquid scintillator.
XENON100 and XENON1T
The XENON100 experiment is used to search for WIMPs , uses 62 kg of liquid, pure xenon as a target and measures the difficult-to-detect charge and light signals that are expected in the rare collisions of WIMPs with xenon atomic nuclei. In order to exclude false signals due to the remaining radioactivity in the vicinity of the detector, only events in the inner 34 kg of the liquid xenon are evaluated as possible signals. In addition, the detector is shielded by layers of copper , polyethylene , lead and water , which further reduces background influences. The analysis of the data from a 13-month running time of the XENON100 detector resulted in an upper limit of 2 · 10 −25 cm² for the cross section of a WIMP mass of 50 GeV.
GERDA
GERDA is looking for the neutrino-free double beta decay . In GERDA (GERmanium Detector Array), bare detectors, which are 86% enriched with the isotope germanium 76, are operated in a shield made of high-purity, liquid argon . In a first phase, the detector has been recording data since November 2011. In a second phase, a new lower limit for the partial half-life of the neutrino-free double beta decay of Ge-76 of 5.3 · 10 25 years was found.
More experiments
In addition to GERDA, CUORE and COBRA are looking for the neutrino-free double beta decay .
In addition to XENON100, the DAMA and CRESST -II experiments are used to search for WIMPs, the hypothetical components of dark matter . DAMA does not use complex per-event differentiation techniques to identify the very rare signals from WIMPs in the disturbing subsurface, but rather the fluctuations in the expected WIMP rate over the course of the year. By evaluating the data from seven years, there was evidence of a WIMP candidate with a mass of 60 GeV / c² and an effective cross-section of 10 −41 cm². But this contradicts the negative results of other WIMP detectors.
LUNA (Laboratory for Underground Nuclear Astrophysics) is an experiment on nuclear astrophysics and operates the only particle accelerator (400 keV, ions) worldwide under the unique conditions of such an underground laboratory .
From 1991 to 2003 the radiochemical experiment GALLEX and the follow-up experiment GNO were in the LNGS.
The Laboratori nazionali del Gran Sasso are, like the three other European underground laboratories, Laboratoire Souterrain de Modane , Laboratorio subterráneo de Canfranc and Boulby Underground Laboratory , affiliated to the ILIAS coordination group.
Web links
- Laboratori nazionali del Gran Sasso
- Slide show. (PDF; 5.44 MB)
Individual evidence
- ↑ a b LNGS overview
- ↑ CNGS-CERN experiment
- ↑ OPERA
- ^ The ICARUS experiment
- ↑ Borexino Experiment Official Web Site ( Memento of the original from October 16, 2007 in the Internet Archive ) Info: The archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this notice.
- ^ LVD: Large Volume Detector
- ↑ XENON experiment
- ↑ GERDA Home Page
- ↑ GERDA collaboration, M. Agostini et al .: Background-free search for neutrinoless double-β decay of 76Ge with GERDA . In: Nature . tape 544 , April 5, 2017, p. 47 , doi : 10.1038 / nature21717 , arxiv : 1703.00570 .
- ↑ cresst.de
- ↑ ILIAS
Coordinates: 42 ° 25 ′ 14 " N , 13 ° 30 ′ 59.1" E