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Gallium Neutrino Observatory
GALLEX or Gallium Experiment was a radiochemical neutrino detection experiment that ran between 1991 and 1997 at the Laboratori Nazionali del Gran Sasso (LNGS). This project was performed by an international collaboration of French, German, Italian, Israeli, Polish and American scientists led by the Max-Planck-Institut für Kernphysik Heidelberg. After brief interruption, the experiment was continued under a new name GNO (Gallium Neutrino Observatory) from May 1998 to April 2003. It was designed to detect solar neutrinos and prove theories related to the Sun's energy creation mechanism. Before this experiment (and the SAGE experiment that ran concurrently), there had been no observation of low energy solar neutrinos. Location The experiment's main components, the tank and the counters, were located in the underground astrophysical laboratory Laboratori Nazionali del Gran Sasso in the Italian Abruzzo province, near L'Aquila, and situated inside the 2912-metre-high Gran Sasso m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neutrino Detection
A neutrino detector is a physics apparatus which is designed to study neutrinos. Because neutrinos only weakly interact with other particles of matter, neutrino detectors must be very large to detect a significant number of neutrinos. Neutrino detectors are often built underground, to isolate the detector from cosmic rays and other background radiation. The field of neutrino astronomy is still very much in its infancy – the only confirmed extraterrestrial sources are the Sun and the supernova 1987A in the nearby Large Magellanic Cloud. Another likely source (three standard deviations) is the blazar TXS 0506+056 about 3.7 billion light years away. Neutrino observatories will "give astronomers fresh eyes with which to study the universe". Various detection methods have been used. Super Kamiokande is a large volume of water surrounded by phototubes that watch for the Cherenkov radiation emitted when an incoming neutrino creates an electron or muon in the water. The Sudbur ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gallium Neutrino Observatory
GALLEX or Gallium Experiment was a radiochemical neutrino detection experiment that ran between 1991 and 1997 at the Laboratori Nazionali del Gran Sasso (LNGS). This project was performed by an international collaboration of French, German, Italian, Israeli, Polish and American scientists led by the Max-Planck-Institut für Kernphysik Heidelberg. After brief interruption, the experiment was continued under a new name GNO (Gallium Neutrino Observatory) from May 1998 to April 2003. It was designed to detect solar neutrinos and prove theories related to the Sun's energy creation mechanism. Before this experiment (and the SAGE experiment that ran concurrently), there had been no observation of low energy solar neutrinos. Location The experiment's main components, the tank and the counters, were located in the underground astrophysical laboratory Laboratori Nazionali del Gran Sasso in the Italian Abruzzo province, near L'Aquila, and situated inside the 2912-metre-high Gran Sasso m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Muon Neutrino
The muon neutrino is an elementary particle which has the symbol () and zero electric charge. Together with the muon it forms the second generation of leptons, hence the name muon neutrino. It was discovered in 1962 by Leon Lederman, Melvin Schwartz and Jack Steinberger. The discovery was rewarded with the 1988 Nobel Prize in Physics. Discovery The muon neutrino or "neutretto" was hypothesized to exist by a number of physicists in the 1940s. The first paper on it may be Shoichi Sakata and Takesi Inoue's two-meson theory of 1942, which also involved two neutrinos. In 1962 Leon M. Lederman, Melvin Schwartz and Jack Steinberger proved the existence of the muon neutrino in an experiment at the Brookhaven National Laboratory. This earned them the 1988 Nobel Prize. Speed In September 2011 OPERA researchers reported that muon neutrinos were apparently traveling at faster than light speed. This result was confirmed again in a second experiment in November 2011. These results wer ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Solar Neutrino Problem
The solar neutrino problem concerned a large discrepancy between the flux of solar neutrinos as predicted from the Sun's luminosity and as measured directly. The discrepancy was first observed in the mid-1960s and was resolved around 2002. The flux of neutrinos at Earth is several tens of billions per square centimetre per second, mostly from the Sun's core. They are nevertheless hard to detect, because they interact very weakly with matter, traversing the whole Earth. Of the three types ( flavors) of neutrinos known in the Standard Model of particle physics, the Sun produces only electron neutrinos. When neutrino detectors became sensitive enough to measure the flow of electron neutrinos from the Sun, the number detected was much lower than predicted. In various experiments, the number deficit was between one half and two thirds. Particle physicists knew that a mechanism, discussed back in 1957 by Bruno Pontecorvo, could explain the deficit in electron neutrinos. However, they ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Standard Model
The Standard Model of particle physics is the theory describing three of the four known fundamental forces (electromagnetism, electromagnetic, weak interaction, weak and strong interactions - excluding gravity) in the universe and classifying all known elementary particles. It was developed in stages throughout the latter half of the 20th century, through the work of many scientists worldwide, with the current formulation being finalized in the mid-1970s upon experimental confirmation of the existence of quarks. Since then, proof of the top quark (1995), the tau neutrino (2000), and the Higgs boson (2012) have added further credence to the Standard Model. In addition, the Standard Model has predicted various properties of weak neutral currents and the W and Z bosons with great accuracy. Although the Standard Model is believed to be theoretically self-consistent and has demonstrated huge successes in providing experimental predictions, it leaves some physics beyond the standard m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Solar Neutrino Unit
The solar neutrino unit (SNU) is a unit of Solar neutrino flux widely used in neutrino astronomy and radiochemical neutrino experiments. It is equal to the neutrino flux producing 10−36 captures per target atom per second. It is convenient given the very low event rates in radiochemical experiments. Typical rate is expected to be from tens SNU to hundred SNU. There are two ways of detecting solar neutrinos: radiochemical and real time experiments. The principle of radiochemical experiments is the reaction of the form ^_Z + \nu_\longrightarrow^_(Z+1)+e^. The daughter nucleus's decay is used in the detection. Production rate of the daughter nucleus is given by R = N\int\Phi(E)\sigma(E)dE, where * \Phi is the solar neutrino flux * \sigma is the cross section for the radiochemical reaction * N is the number of target atoms. With typical neutrino flux of 1010 cm−2 s−1 and a typical interaction cross section of about 10−45 cm2, about 1030 target atoms are required to produce ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Half-life
Half-life (symbol ) is the time required for a quantity (of substance) to reduce to half of its initial value. The term is commonly used in nuclear physics to describe how quickly unstable atoms undergo radioactive decay or how long stable atoms survive. The term is also used more generally to characterize any type of exponential (or, rarely, non-exponential) decay. For example, the medical sciences refer to the biological half-life of drugs and other chemicals in the human body. The converse of half-life (in exponential growth) is doubling time. The original term, ''half-life period'', dating to Ernest Rutherford's discovery of the principle in 1907, was shortened to ''half-life'' in the early 1950s. Rutherford applied the principle of a radioactive element's half-life in studies of age determination of rocks by measuring the decay period of radium to lead-206. Half-life is constant over the lifetime of an exponentially decaying quantity, and it is a characteristic unit for ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
