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Neutrino Ettore Majorana Observatory
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 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.http://www.rcnp.osaka-u.ac.jp/dbd18/Data/Prog/S0303_Patrick.pdf The NEMO-2 and NEMO-3 detectors produced measurements for double neutrino decays and lim ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neutrino Mediterranean Observatory
The Cubic Kilometre Neutrino Telescope, or KM3NeT, is a future European research infrastructure that will be located at the bottom of the Mediterranean Sea. It will host the next-generation neutrino telescope in the form of a water Cherenkov detector with an instrumented volume of several cubic kilometres distributed over three locations in the Mediterranean: KM3NeT-Fr (off Toulon, France), KM3NeT-It (off Portopalo di Capo Passero, Sicily, Italy) and KM3NeT-Gr (off Pylos, Peloponnese, Greece). The KM3NeT project continues work done under the ANTARES (telescope built off coast of France), NEMO (planned telescope off coast of Italy) and NESTOR (planned telescope off coast of Greece) neutrino telescope projects. KM3NeT will search for neutrinos from distant astrophysical sources like supernova remnants, gamma-ray bursts, supernovae or colliding stars and will be a powerful tool in the search for dark matter in the universe. Its prime objective is to detect neutrinos from sourc ... [...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. At least three isotopes—110Cd, 111Cd, and 112Cd—are absolutely stable (except, theoretically, to spontaneous fission). 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 ... [...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 al ... [...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 Y. Chikashige, R. N. Mohapatra and R. D. 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 theories and t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Q Value (nuclear Science)
In nuclear physics and chemistry, the value for a reaction is the amount of energy absorbed or released during the nuclear 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. 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. : Q = (\,m_\text - m_\text\,) \times \text where the masses are in atomic mass units. Also both \;m_\text\; and \;m_\text\; are the sums of the reactant and product masses respectively. Definition The conservation of energy, between the initial and final energy of a nuclear process \text E_\text = E_\text \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 = ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Positron
The positron or antielectron is the antiparticle or the antimatter counterpart of the electron. It has an electric charge of +1 '' e'', a spin of 1/2 (the same as the electron), and the same mass as an 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 to explain the Zeeman effect. The paper did not explicitly predict a new particle but did allow for electrons having either positive or negative ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electron
The electron ( or ) is a subatomic particle with a negative one elementary electric charge. Electrons belong to the first generation of the lepton particle family, and are generally thought to be elementary particles because they have no known components or substructure. The electron's mass is approximately 1/1836 that of the proton. Quantum mechanical properties of the electron include an intrinsic angular momentum ( spin) of a half-integer value, expressed in units of the reduced Planck constant, . Being fermions, no two electrons can occupy the same quantum state, in accordance with the Pauli exclusion principle. Like all elementary particles, electrons exhibit properties of both particles and waves: They can collide with other particles and can be diffracted like light. The wave properties of electrons are easier to observe with experiments than those of other particles like neutrons and protons because electrons have a lower mass and hence a longer de Broglie wavele ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Copper
Copper is a chemical element with the symbol Cu (from la, cuprum) 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 metallic form ( native metals). This led to very early human use in several regions, from circa 8000 BC. Thousands of years later, it was the first metal to be smelted from sulfide ores, circa 5000 BC; the first metal to be cast into a shape in a mold, c. 4000 BC; and the first metal to be purposely alloyed with another metal, tin, to create ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tellurium
Tellurium is a chemical element with the 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 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.Anderson, Don L.; "Chemical Composition of the Mantle" in ''Theory of the Earth'', pp. 147-175 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 ar ... [...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 process of double beta decay. Its half-life is about 6.4×1019 years, so for all practical purposes it can be treated as stable. One factor contributing to this unusual stability is that 20 and 28 are both magic numbers, making 48Ca a "doubly magic" nucleus. Since 48Ca 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 heaviest five elements on the periodic table, from flerovium to oganesson. Heavier nuclei generally require a greater fraction of neutron ... [...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 2.0×1019 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 1.53 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 , - , 78Zr , style="text-align:right" , 40 , style="text-align:right" , 38 , 77.95523(54)# , 50# ms 170 ns, , , 0+ , , , - , rowspan=2, 79Zr , rowspan=2 style="text-a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neodymium-150
Naturally occurring neodymium (60Nd) is composed of 5 stable isotopes, 142Nd, 143Nd, 145Nd, 146Nd and 148Nd, with 142Nd being the most abundant (27.2% natural abundance), and 2 long-lived radioisotopes, 144Nd and 150Nd. In all, 33 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 2.29×1015 years) and 150Nd (double beta decay, t1/2 of 7×1018 years). All of the remaining radioactive isotopes have half-lives that are less than 12 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 13 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 before the most abundant stable isotope, 142Nd, are electron capture and positron decay, and the primary mode after is b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
