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NEMO-3 Collaboration
The Neutrino Ettore Majorana Observatory (NEMO experiment) is an international collaboration of scientists searching for neutrinoless double beta decay (0νββ). The collaboration has been active since 1989. Observation of 0νββ would indicate neutrinos are Majorana fermion, Majorana particles and could be used to measure the neutrino mass. It is located in the Modane Underground Laboratory (LSM) in the Fréjus Road Tunnel. The experiment has (as of 2018) had 3 detectors, NEMO-1, NEMO-2, NEMO-3 (and a demonstrator module of SuperNEMO-detector) and is planning (as of 2018) to construct a new detector SuperNEMO. The NEMO-1 and NEMO-2 prototype detectors were used until 1997. Latest experiment NEMO-3 was under design and construction from 1994 onwards, took data from January 2003 to January 2011 and the final data analysis was published in 2018. The NEMO-2 and NEMO-3 detectors produced measurements for double neutrino decays and limits for neutrinoless double-beta decay for a nu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neutrino Mediterranean Observatory
The Cubic Kilometre Neutrino Telescope, or KM3NeT, is a European research infrastructure located at the bottom of the Mediterranean Sea. It hosts water Cherenkov radiation, Cherenkov neutrino astronomy, neutrino telescopes designed to detect and study neutrinos from distant astrophysical sources as well as from our own atmosphere, contributing significantly to both astrophysics and particle physics knowledge. Arrays of thousands of optical sensor modules detect the faint Cherenkov light in the deep sea from charged particles originating from interactions of neutrinos in water or rock in the vicinity of the detector. The position and direction of the optical modules and the time of arrival of the light on the photomultipliers inside are recorded with high precision. Properties of the particles, like their trajectory and energy, are reconstructed from these measurements. The KM3NeT project foresees the construction of several of these detectors in the depths of the Mediterranean Sea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cadmium-116
Naturally occurring cadmium (48Cd) is composed of 8 isotopes. For two of them, natural radioactivity was observed, and three others are predicted to be radioactive but their decays have not been observed, due to extremely long half-lives. The two natural radioactive isotopes are 113Cd (beta decay, half-life is 8.04 × 1015 years) and 116Cd (two-neutrino double beta decay, half-life is 2.8 × 1019 years). The other three are 106Cd, 108Cd (double electron capture), and 114Cd (double beta decay); only lower limits on their half-life times have been set. Three isotopes—110Cd, 111Cd, and 112Cd—are theoretically stable. Among the isotopes absent in natural cadmium, the most long-lived are 109Cd with a half-life of 462.6 days, and 115Cd with a half-life of 53.46 hours. All of the remaining radioactive isotopes have half-lives that are less than 2.5 hours and the majority of these have half-lives that are less than 5 minutes. This element also has 12 known meta states, with the most st ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zirconium(IV) Silicate
Zirconium silicate, also zirconium orthosilicate, ZrSiO4, is a chemical compound, a silicate of zirconium. It occurs in nature as zircon, a silicate mineral. Powdered zirconium silicate is also known as zircon flour. Zirconium silicate is usually colorless, but impurities induce various colorations. It is insoluble in water, acids, alkali and aqua regia. Hardness is 7.5 on the Mohs scale. Structure and bonding Zircon consists of 8-coordinated Zr4+ centers linked to tetrahedral orthosilicate SiO44- sites. The oxygen atoms are all triply bridging, each with the environment OZr2Si. Given its highly crosslinked structure, the material is hard, and hence prized as gemstone and abrasive. Zr(IV) is a d0 ion. Consequently the material is colorless and diamagnetic. Production Zirconium silicate occurs in nature as mineral zircon. Concentrated sources of zircon are rare. It is mined from sand deposits and separated by gravity. Some sands contain a few percent of zircon. It can als ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Majoron
In particle physics, majorons (named after Ettore Majorana) are a hypothetical type of Goldstone boson that are conjectured to mediate the neutrino mass violation of lepton number or ''B'' − ''L'' in certain high energy collisions such as : + → + + Where two electrons collide to form two W bosons and the majoron J. The U(1)B−L symmetry is assumed to be global so that the majoron is not "eaten up" by the gauge boson and spontaneously broken. Majorons were originally formulated in four dimensions by Yuichi Chikashige, Rabindra Mohapatra and Roberto Peccei to understand neutrino masses by the seesaw mechanism and are being searched for in the neutrino-less double beta decay process. The name majoron was suggested by Graciela Gelmini as a derivative of the last name Majorana with the suffix -on typical of particle names like electron, proton, neutron, etc. There are theoretical extensions of this idea into supersymmetric the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Q Value (nuclear Science)
In nuclear physics and chemistry, the value for a nuclear reaction is the amount of energy absorbed or released during the reaction. The value relates to the enthalpy of a chemical reaction or the energy of radioactive decay products. It can be determined from the masses of reactants and products: : Q = (m_\text - m_\text) \times \text, where m_\text and m_\text are the sums of the reactant and product masses in atomic mass units. values affect reaction rates. In general, the larger the positive value for the reaction, the faster the reaction proceeds, and the more likely the reaction is to "favor" the products. Definition The conservation of energy, between the initial and final energy of a nuclear process (E_\text = E_\text), enables the general definition of based on the mass–energy equivalence. For any radioactive particle decay, the kinetic energy difference will be given by : Q = K_\text - K_\text = (m_\text - m_\text) \, c^2, where denotes the kinetic energy o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Positron
The positron or antielectron is the particle with an electric charge of +1''elementary charge, e'', a Spin (physics), spin of 1/2 (the same as the electron), and the same Electron rest mass, mass as an electron. It is the antiparticle (antimatter counterpart) of the electron. When a positron collides with an electron, annihilation occurs. If this collision occurs at low energies, it results in the production of two or more photons. Positrons can be created by positron emission radioactive decay (through weak interactions), or by pair production from a sufficiently energetic photon which is interacting with an atom in a material. History Theory In 1928, Paul Dirac published a paper proposing that electrons can have both a positive and negative charge. This paper introduced the Dirac equation, a unification of quantum mechanics, special relativity, and the then-new concept of electron Spin (physics), spin to explain the Zeeman effect. The paper did not explicitly predict a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electron
The electron (, or in nuclear reactions) is a subatomic particle with a negative one elementary charge, elementary electric charge. It is a fundamental particle that comprises the ordinary matter that makes up the universe, along with up quark, up and down quark, down quarks. Electrons are extremely lightweight particles that orbit the positively charged atomic nucleus, nucleus of atoms. Their negative charge is balanced by the positive charge of protons in the nucleus, giving atoms their overall electric charge#Charge neutrality, neutral charge. Ordinary matter is composed of atoms, each consisting of a positively charged nucleus surrounded by a number of orbiting electrons equal to the number of protons. The configuration and energy levels of these orbiting electrons determine the chemical properties of an atom. Electrons are bound to the nucleus to different degrees. The outermost or valence electron, valence electrons are the least tightly bound and are responsible for th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Copper
Copper is a chemical element; it has symbol Cu (from Latin ) and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pinkish-orange color. Copper is used as a conductor of heat and electricity, as a building material, and as a constituent of various metal alloys, such as sterling silver used in jewelry, cupronickel used to make marine hardware and coins, and constantan used in strain gauges and thermocouples for temperature measurement. Copper is one of the few metals that can occur in nature in a directly usable, unalloyed metallic form. This means that copper is a native metal. This led to very early human use in several regions, from . Thousands of years later, it was the first metal to be smelted from sulfide ores, ; the first metal to be cast into a shape in a mold, ; and the first metal to be purposely alloyed with another metal, tin, to create bronze, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tellurium
Tellurium is a chemical element; it has symbol Te and atomic number 52. It is a brittle, mildly toxic, rare, silver-white metalloid. Tellurium is chemically related to selenium and sulfur, all three of which are chalcogens. It is occasionally found in its native form as elemental crystals. Tellurium is far more common in the Universe as a whole than on Earth. Its extreme rarity in the Earth's crust, comparable to that of platinum, is due partly to its formation of a volatile hydride that caused tellurium to be lost to space as a gas during the hot nebular formation of Earth. Tellurium-bearing compounds were first discovered in 1782 in a gold mine in Kleinschlatten, Transylvania (now Zlatna, Romania) by Austrian mineralogist Franz-Joseph Müller von Reichenstein, although it was Martin Heinrich Klaproth who named the new element in 1798 after the Latin 'earth'. Gold telluride minerals are the most notable natural gold compounds. However, they are not a commercially signif ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Calcium-48
Calcium-48 is a scarce isotope of calcium containing 20 protons and 28 neutrons. It makes up 0.187% of natural calcium by mole fraction. Although it is unusually neutron-rich for such a light nucleus, its beta decay is extremely hindered, and so the only radioactive decay pathway that it has been observed to undergo is the extremely rare double beta decay (2β). Its half-life is about 6.4×10 years, so for all practical purposes it can be treated as stable. One cause of this unusual stability is that 20 and 28 are both magic numbers, making Ca a "doubly magic" nucleus. Since Ca is both practically stable and neutron-rich, it is a valuable starting material for the production of new nuclei in particle accelerators, both by fragmentation and by fusion reactions with other nuclei, for example in the discoveries of the five heaviest known elements, from flerovium to oganesson (atomic numbers 114 through 118). Heavier nuclei generally require a greater fraction of neutrons for maximu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zirconium-96
Naturally occurring zirconium (40Zr) is composed of four stable isotopes (of which one may in the future be found radioactive), and one very long-lived radioisotope (96Zr), a primordial nuclide that decays via double beta decay with an observed half-life of 2.34 × 1019 years; it can also undergo single beta decay, which is not yet observed, but the theoretically predicted value of t1/2 is 2.4 × 1020 years. The second most stable radioisotope is 93Zr, which has a half-life of 1.61 million years. Thirty other radioisotopes have been observed. All have half-lives less than a day except for 95Zr (64.02 days), 88Zr (83.4 days), and 89Zr (78.41 hours). The primary decay mode is electron capture for isotopes lighter than 92Zr, and the primary mode for heavier isotopes is beta decay. List of isotopes , -id=Zirconium-77 , 77Zr , style="text-align:right" , 40 , style="text-align:right" , 37 , 76.96608(43)# , 100# μs , , , 3/2−# , , , -id=Zirconium-78 , 78Zr , ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neodymium-150
Naturally occurring neodymium (60Nd) is composed of five stable isotopes, 142Nd, 143Nd, 145Nd, 146Nd and 148Nd, with 142Nd being the most abundant (27.2% natural abundance), and two long-lived radioisotopes, 144Nd and 150Nd. In all, 35 radioisotopes of neodymium have been characterized up to now, with the most stable being naturally occurring isotopes 144Nd (alpha decay, a half-life (t1/2) of years) and 150Nd (double beta decay, t1/2 of years), and for practical purposes they can be considered to be stable as well. All of the remaining radioactive isotopes have half-lives that are less than 11 days, and the majority of these have half-lives that are less than 70 seconds; the most stable artificial isotope is 147Nd with a half-life of 10.98 days. This element also has 15 known meta states with the most stable being 139mNd (t1/2 5.5 hours), 135mNd (t1/2 5.5 minutes) and 133m1Nd (t1/2 ~70 seconds). The primary decay modes for isotopes lighter than the most abundant stable isotope ( ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
