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China Jinping Underground Laboratory
The China Jinping Underground Laboratory () is a deep underground laboratory in the Jinping Mountains of Sichuan, China. The cosmic ray rate in the laboratory is under 0.2 muons/m2/day, placing the lab at a depth of 6720 meter water equivalent, m.w.e. and making it the best-shielded underground laboratory in the world. The actual depth of the laboratory is , yet there is horizontal access so equipment may be brought in by truck. Although the marble through which the tunnels are dug is considered "Underground mining (hard rock), hard rock", at the great depth it presents greater geotechnical engineering challenges than the even harder igneous rocks in which other deep laboratories are constructed. The water pressure in the rock is also inconvenient. But marble has the advantage for radiation shielding of being low in radionuclides, such as Potassium-40, 40K, Radium-226, 226Ra, Thorium-232, 232Th, and Uranium-238, 238U. This in turn leads to low levels of radon (Radon-2 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dark Matter
Dark matter is a hypothetical form of matter thought to account for approximately 85% of the matter in the universe. Dark matter is called "dark" because it does not appear to interact with the electromagnetic field, which means it does not absorb, reflect, or emit electromagnetic radiation and is, therefore, difficult to detect. Various astrophysical observationsincluding gravitational effects which cannot be explained by currently accepted theories of gravity unless more matter is present than can be seenimply dark matter's presence. For this reason, most experts think that dark matter is abundant in the universe and has had a strong influence on its structure and evolution. The primary evidence for dark matter comes from calculations showing that many galaxies would behave quite differently if they did not contain a large amount of unseen matter. Some galaxies would not have formed at all and others would not move as they currently do. Other lines of evidence include observa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Uranium-238
Uranium-238 (238U or U-238) is the most common isotope of uranium found in nature, with a relative abundance of 99%. Unlike uranium-235, it is non-fissile, which means it cannot sustain a chain reaction in a thermal-neutron reactor. However, it is fissionable by fast neutrons, and is ''fertile'', meaning it can be transmuted to fissile plutonium-239. 238U cannot support a chain reaction because inelastic scattering reduces neutron energy below the range where fast fission of one or more next-generation nuclei is probable. Doppler broadening of 238U's neutron absorption resonances, increasing absorption as fuel temperature increases, is also an essential negative feedback mechanism for reactor control. Around 99.284% of natural uranium's mass is uranium-238, which has a half-life of 1.41 seconds (4.468 years, or 4.468 billion years). Due to its natural abundance and half-life relative to other radioactive elements, 238U produces ~40% of the radioactive heat produced within th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Laboratori Nazionali Del Gran Sasso
Laboratori Nazionali del Gran Sasso (LNGS) is the largest underground research center in the world. Situated below Gran Sasso mountain in Italy, it is well known for particle physics research by the INFN. In addition to a surface portion of the laboratory, there are extensive underground facilities beneath the mountain. The nearest towns are L'Aquila and Teramo. The facility is located about 120 km from Rome. The primary mission of the laboratory is to host experiments that require a low background environment in the fields of astroparticle physics and nuclear astrophysics and other disciplines that can profit of its characteristics and of its infrastructures. The LNGS is, like the three other European underground astroparticle laboratories (Laboratoire Souterrain de Modane, Laboratorio subterráneo de Canfranc, and Boulby Underground Laboratory), a member of the coordinating group ILIAS. Facilities The laboratory consists of a surface facility, located within the Gran ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stadium (geometry)
A stadium is a two-dimensional geometric shape constructed of a rectangle with semicircles at a pair of opposite sides. The same shape is known also as a pill shape, discorectangle, squectangle, obround, or sausage body. The shape is based on a stadium, a place used for athletics and horse racing tracks. A stadium may be constructed as the Minkowski sum of a disk and a line segment. Alternatively, it is the neighborhood of points within a given distance from a line segment. A stadium is a type of oval. However, unlike some other ovals such as the ellipses, it is not an algebraic curve because different parts of its boundary are defined by different equations. Formulas The perimeter of a stadium is calculated by the formula P = 2 (\pi r+a) where ''a'' is the length of the straight sides and ''r'' is the radius of the semicircles. With the same parameters, the area of the stadium is A = \pi r^2 + 2ra = r(\pi r + 2a). Bunimovich stadium When this shape is used in the study o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
PandaX
The Particle and Astrophysical Xenon Detector, or PandaX, is a dark matter detection experiment at China Jinping Underground Laboratory (CJPL) in Sichuan, China. The experiment occupies the deepest underground laboratory in the world, and is among the largest of its kind. Participants The experiment is run by an international team of about 40 scientists, led by researchers at China's Shanghai Jiao Tong University. The project began in 2009 with researchers from Shanghai Jiao Tong University, Shandong University, the Shanghai Institute of Applied Physics ( zh), and the Chinese Academy of Sciences. Researchers from the University of Maryland, Peking University, and the University of Michigan joined two years later. The PandaX team also includes members from the Ertan Hydropower Development Company. Scientists from University of Science and Technology of China, China Institute of Atomic Energy and Sun Yat-Sen University joined PandaX in 2015. Design and construction PandaX is a di ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Liquid Nitrogen
Liquid nitrogen—LN2—is nitrogen in a liquid state at low temperature. Liquid nitrogen has a boiling point of about . It is produced industrially by fractional distillation of liquid air. It is a colorless, low viscosity liquid that is widely used as a coolant. Physical properties The diatomic character of the N2 molecule is retained after liquefaction. The weak van der Waals interaction between the N2 molecules results in little interatomic interaction, manifested in its very low boiling point. The temperature of liquid nitrogen can readily be reduced to its freezing point by placing it in a vacuum chamber pumped by a vacuum pump. Liquid nitrogen's efficiency as a coolant is limited by the fact that it boils immediately on contact with a warmer object, enveloping the object in an insulating layer of nitrogen gas bubbles. This effect, known as the Leidenfrost effect, occurs when any liquid comes in contact with a surface which is significantly hotter than its boiling ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
China Dark Matter Experiment
The China Dark Matter Experiment (CDEX) is a search for dark matter WIMP particles at the China Jinping Underground Laboratory. CDEX was the first experiment to be hosted at CJPL, beginning construction of its shield in June 2010, the same month that laboratory construction was completed, and before CJPL's official opening on 12 December. CDEX has p-type point-contact germanium detector surrounded by NaI(Tl) crystals, similar to the CoGeNT experiment. The CDEX-0 prototype was used to develop the current CDEX-1 detector, which has a detector mass of roughly 1 kg. Future plans include scaling to CDEX-10 and CDEX-1T. CDEX-1 had first low mass results in 2013 and published limits on WIMP masses 6–20 GeV GEV may refer to: * ''G.E.V.'' (board game), a tabletop game by Steve Jackson Games * Ashe County Airport, in North Carolina, United States * Gällivare Lapland Airport, in Sweden * Generalized extreme value distribution * Gev Sella, Israeli-Sou ... in 2014. Refer ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radon Gas
Radon is a chemical element with the symbol Rn and atomic number 86. It is a radioactive, colourless, odourless, tasteless noble gas. It occurs naturally in minute quantities as an intermediate step in the normal radioactive decay chains through which thorium and uranium slowly decay into various short-lived radioactive elements and lead. Radon itself is the immediate decay product of radium. Its most stable isotope, 222Rn, has a half-life of only 3.8 days, making it one of the rarest elements. Since thorium and uranium are two of the most common radioactive elements on Earth, while also having three isotopes with half-lives on the order of several billion years, radon will be present on Earth long into the future despite its short half-life. The decay of radon produces many other short-lived nuclides, known as "radon daughters", ending at stable isotopes of lead. [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jinping-II Dam
The Jinping-II Dam (), also known as the Jinping-II Hydropower Station, is a gravity dam on the Jinping Bend of the Yalong River (Yalong Jiang) in Sichuan, China. Construction on the project began in 2007 and it was complete in 2014. Its hydroelectric power station has a 4,800 MW installed capacity. While Jinping-I relies on a conventional tall dam and large reservoir to supply water, Jinping-II uses a much smaller dam, located 7.5 km downstream of Jinping-I, to divert water into four 16.6 km long headrace tunnels. These tunnels connect to a downstream point on the same river at a much lower elevation, providing a head of water without flooding a large area of land. History Harnessing hydropower on the Jinping Bend of the Yalong River has been in planning for decades. The river makes a hairpin bend 150 km long around the Jinping Mountains, but the downstream part of the river on the opposite side of the mountain is separated by only 16 km. In that dista ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Xichang Qingshan Airport
Xichang Qingshan Airport () is an airport serving Xichang, the seat of Liangshan Yi Autonomous Prefecture in Sichuan Province, China. The airport started an expansion project in February 2010. Airlines and destinations See also *List of airports in the People's Republic of China This is a list of public airports in the People's Republic of China grouped by provincial level division and sorted by main city served. It includes airports that are being built or scheduled for construction, but excludes defunct airports and ... References {{authority control Airports in Sichuan ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chengdu
Chengdu (, ; Simplified Chinese characters, simplified Chinese: 成都; pinyin: ''Chéngdū''; Sichuanese dialects, Sichuanese pronunciation: , Standard Chinese pronunciation: ), Chinese postal romanization, alternatively Romanization of Chinese, romanized as Chengtu, is a Sub-provincial division, sub-provincial city which serves as the Capital city, capital of the Chinese province of Sichuan. With a population of 20,937,757 inhabitants during the 2020 Chinese census, it is the fourth most populous city in China, and it is the only city apart from the four Direct-administered municipalities of China, direct-administered municipalities with a population of over 20 million (the other three are Chongqing, Shanghai and Beijing). It is traditionally the hub in Southwest China. Chengdu is located in central Sichuan. The surrounding Chengdu Plain is known as the "Country of Heaven" () and the "Land of Abundance". Its prehistoric settlers included the Sanxingdui culture. The site of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Liangshan Yi Autonomous Prefecture
Liangshan (; Yi: ''Niep Sha'', pronounced ), officially the Liangshan Yi Autonomous Prefecture, is an autonomous prefecture occupying much of the southern extremity of Sichuan province, People's Republic of China; its seat is Xichang. Liangshan has an area of and over 4.5 million inhabitants (2010). It is also has the largest population of ethnic Yi nationally. Liangshan Yi contains a number of isolated villages high up on its cliffs, often known as " cliff villages". Xichang has the Xichang Qingshan Airport and the Xichang Satellite Launch Center. The prefecture also features a substantial network of railways for both passengers and freight. Terrain and climate The Anning River, which runs into the Jinsha River (Yangtze River headwaters), is the main river in the area. Owing to its low latitude and high elevation, Liangshan has a mild climate. Under the Köppen system, the prefecture belongs to the humid subtropical zone (Köppen ''Cwa''). Winters feature mild days and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
