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CJPL
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 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 "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 40K, 226Ra, 232Th, and 238U. This in turn leads to low levels of radon ( 222Rn) in the atmosphere. The laboratory is in Liangshan in southern Sichuan, about southwest of Chengdu. ... [...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 In physics, an electronvolt (symbol eV), also written electron-volt and electron volt, is the measure of an amount of kinetic energy gained by a single electron accelerating through an electric potential difference of one volt in vacuum. When us ... in 2014. Refere ... [...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] |
Dark Matter
In astronomy, dark matter is an invisible and hypothetical form of matter that does not interact with light or other electromagnetic radiation. Dark matter is implied by gravity, gravitational effects that cannot be explained by general relativity unless more matter is present than can be observed. Such effects occur in the context of Galaxy formation and evolution, formation and evolution of galaxies, gravitational lensing, the observable universe's current structure, mass position in galactic collisions, the motion of galaxies within galaxy clusters, and cosmic microwave background Anisotropy, anisotropies. Dark matter is thought to serve as gravitational scaffolding for cosmic structures. After the Big Bang, dark matter clumped into blobs along narrow filaments with superclusters of galaxies forming a cosmic web at scales on which entire galaxies appear like tiny particles. In the standard Lambda-CDM model of cosmology, the mass–energy equivalence, mass–energy content o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Uranium-238
Uranium-238 ( 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 wit ... [...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 G ... [...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, 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 of dynamical ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Liquid Nitrogen
Liquid nitrogen (LN2) is nitrogen in a liquid state at cryogenics, low temperature. Liquid nitrogen has a boiling point of about . It is produced industrially by fractional distillation of liquid air. It is a colorless, mobile liquid whose viscosity is about one-tenth that of acetone (i.e. roughly one-thirtieth that of water at room temperature). Liquid nitrogen 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 attraction. This is the cause of nitrogen's unusually 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. Thi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radon Gas
Radon is a chemical element; it has Symbol (chemistry), symbol Rn and atomic number 86. It is a radioactive decay, radioactive noble gas and is colorless and odorless. Of the three naturally occurring radon Isotope, isotopes, only radon-222, Rn has a sufficiently long half-life (3.825 days) for it to be released from the soil and rock where it is generated. Radon isotopes are the immediate decay products of radium isotopes. The instability of Rn, its most stable isotope, makes radon one of the rarest elements. Radon will be present on Earth for several billion more years despite its short half-life, because it is constantly being produced as a step in the decay chains of uranium-238, U and thorium-232, Th, both of which are abundant radioactive nuclides with half-lives of at least several billion years. The decay of radon produces many other short-lived nuclides, known as "radon daughters", ending at stable isotopes of lead. Radon-222, Rn occurs in significant quantities as a step i ... [...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 or county served. It includes civil airports and certified general airports, but excludes general airports filed und ... References {{authority control Airports in Sichuan Xichang ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chengdu
Chengdu; Sichuanese dialects, Sichuanese pronunciation: , Standard Chinese pronunciation: ; Chinese postal romanization, previously Romanization of Chinese, romanized as Chengtu. is the capital city of the Chinese province of Sichuan. With a population of 20,937,757 at the 2020 Chinese census, 2020 census, it is the fourth most populous city in China, and it is the only city with a population of over 20 million apart from Direct-administered municipality, direct-administered municipalities. It is traditionally the hub of Western China. Chengdu is 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 Dujiangyan, an ancient irrigation system, is designated as a World Heritage Site. The Jin River (Sichuan), Jin River flows through the city. Chengdu's culture reflects that of its province, Sichuan; in 2011, it was recognized by UNESCO as a city of ga ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Liangshan Yi Autonomous Prefecture
Liangshan Yi Autonomous Prefecture (Nuosu language, Northern Yi: /nɛ˨˩ʂa˧/) is an autonomous prefecture occupying much of the southern extremity of Sichuan province, People's Republic of China. Its seat is Xichang. Liangshan covers an area of and has over 4.8 million inhabitants as of 2020. It has the largest population of Yi people, ethnic Yi (or Nosu) among China's prefectures. Liangshan 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. Governance Liangshan Prefecture Public Security Bureau The Liangshan Prefecture Public Security Bureau () is the primary law enforcement agency of Liangshan. It contains an economic crime investigation unit, a patrol unit, a narcotics unit an immigration unit, a cyber-crime unit, a traffic police unit, a SWAT unit a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
