|
Axion Dark Matter Experiment
The Axion Dark Matter Experiment (ADMX, also written as ''Axion Dark Matter eXperiment'' in the project's documentation) uses a resonant microwave cavity within a large superconducting magnet to search for cold dark matter axions in the local galactic dark matter halo. Unusual for a dark matter detector, it is not located deep underground. Sited at the Center for Experimental Nuclear Physics and Astrophysics (CENPA) at the University of Washington, ADMX is a large collaborative effort with researchers from universities and laboratories around the world. Background The axion is a hypothetical elementary particle originally postulated to solve the strong CP problem. The axion is also an extremely attractive dark matter candidate. The axion is the puzzle piece allowing these two mysteries to fit naturally into our understanding of the universe. Strong CP problem The axion was originally postulated to exist as part of the solution to the "strong CP problem". This problem arose fro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Microwave Cavity
A microwave cavity or ''radio frequency (RF) cavity'' is a special type of resonator, consisting of a closed (or largely closed) metal structure that confines electromagnetic fields in the microwave region of the spectrum. The structure is either hollow or filled with dielectric material. The microwaves bounce back and forth between the walls of the cavity. At the cavity's resonant frequencies they reinforce to form standing waves in the cavity. Therefore, the cavity functions similarly to an organ pipe or sound box in a musical instrument, oscillating preferentially at a series of frequencies, its resonant frequencies. Thus it can act as a bandpass filter, allowing microwaves of a particular frequency to pass while blocking microwaves at nearby frequencies. A microwave cavity acts similarly to a resonant circuit with extremely low loss at its frequency of operation, resulting in quality factors (Q factors) up to the order of 106, compared to 102 for circuits made with s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
University Of Florida
The University of Florida (Florida or UF) is a public land-grant research university in Gainesville, Florida. It is a senior member of the State University System of Florida, traces its origins to 1853, and has operated continuously on its Gainesville campus since September 1906. After the Florida state legislature's creation of performance standards in 2013, the Florida Board of Governors designated the University of Florida as a "preeminent university". For 2022, '' U.S. News & World Report'' ranked Florida as the fifth (tied) best public university and 28th (tied) best university in the United States. The University of Florida is the only member of the Association of American Universities in Florida and is classified among "R1: Doctoral Universities – Very high research activity". The university is accredited by the Southern Association of Colleges and Schools (SACS). It is the third largest Florida university by student population,Nathan Crabbe, UF is no longer la ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Noise Temperature
In electronics, noise temperature is one way of expressing the level of available noise power introduced by a component or source. (This is to be distinguished from Temperature Noise in Thermodynamics or Principal Interferrometric Analysis Over Cross-Type Interference Between different noise types) The power spectral density of the noise is expressed in terms of the temperature (in kelvins) that would produce that level of Johnson–Nyquist noise, thus: :\frac = k_\text T where: * P_\text is the noise power (in W, watts) * B is the total bandwidth (Hz, hertz) over which that noise power is measured * k_\text is the Boltzmann constant (, joules per kelvin) * T is the noise temperature (K, kelvin) Thus the noise temperature is proportional to the power spectral density of the noise, P_\text/ B. That is the power that would be absorbed from the component or source by a matched load. Noise temperature is generally a function of frequency, unlike that of an ideal resistor which ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dilution Refrigerator
A 3He/4He dilution refrigerator is a cryogenics, cryogenic device that provides continuous cooling to temperatures as low as 2 Kelvin, mK, with no moving parts in the low-temperature region. The cooling power is provided by the heat of mixing of the Helium-3 and Helium-4 isotopes. The dilution refrigerator was first proposed by Heinz London in the early 1950s, and was experimentally realized in 1964 in the Kamerlingh Onnes Laboratorium at Leiden University. The field of dilution refrigeration is reviewed by Zu et al. Theory of operation The refrigeration process uses a mixture of two isotopes of helium: helium-3 and helium-4. When cooled below approximately Orders of magnitude (temperature), 870 Kelvin, millikelvins, the mixture undergoes spontaneous phase separation to form a 3He-rich phase (the concentrated phase) and a 3He-poor phase (the dilute phase). As shown in the phase diagram, at very low temperatures the concentrated phase is essentially pure 3He, whil ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
HFET
A high-electron-mobility transistor (HEMT), also known as heterostructure FET (HFET) or modulation-doped FET (MODFET), is a field-effect transistor incorporating a junction between two materials with different band gaps (i.e. a heterojunction) as the channel instead of a doped region (as is generally the case for a MOSFET). A commonly used material combination is GaAs with AlGaAs, though there is wide variation, dependent on the application of the device. Devices incorporating more indium generally show better high-frequency performance, while in recent years, gallium nitride HEMTs have attracted attention due to their high-power performance. Like other FETs, HEMTs are used in integrated circuits as digital on-off switches. FETs can also be used as amplifiers for large amounts of current using a small voltage as a control signal. Both of these uses are made possible by the FET’s unique current–voltage characteristics. HEMT transistors are able to operate at higher frequen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ADMX Magnet Installation
The Axion Dark Matter Experiment (ADMX, also written as ''Axion Dark Matter eXperiment'' in the project's documentation) uses a resonant microwave cavity within a large superconducting magnet to search for cold dark matter axions in the local galactic dark matter halo. Unusual for a dark matter detector, it is not located deep underground. Sited at the Center for Experimental Nuclear Physics and Astrophysics (CENPA) at the University of Washington, ADMX is a large collaborative effort with researchers from universities and laboratories around the world. Background The axion is a hypothetical elementary particle originally postulated to solve the strong CP problem. The axion is also an extremely attractive dark matter candidate. The axion is the puzzle piece allowing these two mysteries to fit naturally into our understanding of the universe. Strong CP problem The axion was originally postulated to exist as part of the solution to the "strong CP problem". This problem arose from ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
SQUID
True squid are molluscs with an elongated soft body, large eyes, eight arms, and two tentacles in the superorder Decapodiformes, though many other molluscs within the broader Neocoleoidea are also called squid despite not strictly fitting these criteria. Like all other cephalopods, squid have a distinct head, bilateral symmetry, and a mantle. They are mainly soft-bodied, like octopuses, but have a small internal skeleton in the form of a rod-like gladius (cephalopod), gladius or pen, made of chitin. Squid diverged from other cephalopods during the Jurassic and occupy a similar role to teleost fish as open water predators of similar size and behaviour. They play an important role in the open water food web. The two long tentacles are used to grab prey and the eight arms to hold and control it. The beak then cuts the food into suitable size chunks for swallowing. Squid are rapid swimmers, moving by Aquatic locomotion#Jet propulsion, jet propulsion, and largely locate their ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Galactic Halo
A galactic halo is an extended, roughly spherical component of a galaxy which extends beyond the main, visible component. Several distinct components of galaxies comprise the halo: * the stellar halo * the galactic corona (hot gas, i.e. a plasma) * the dark matter halo The distinction between the halo and the main body of the galaxy is clearest in spiral galaxies, where the spherical shape of the halo contrasts with the flat disc. In an elliptical galaxy, there is no sharp transition between the other components of the galaxy and the halo. A halo can be studied by observing its effect on the passage of light from distant bright objects like quasars that are in line of sight beyond the galaxy in question. Components of the galactic halo Stellar halo The stellar halo is a nearly spherical population of field stars and globular clusters. It surrounds most disk galaxies as well as some elliptical galaxies of type cD. A low amount (about one percent) of a galaxy's stellar mas ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Milky Way
The Milky Way is the galaxy that includes our Solar System, with the name describing the galaxy's appearance from Earth: a hazy band of light seen in the night sky formed from stars that cannot be individually distinguished by the naked eye. The term ''Milky Way'' is a translation of the Latin ', from the Greek ('), meaning "milky circle". From Earth, the Milky Way appears as a band because its disk-shaped structure is viewed from within. Galileo Galilei first resolved the band of light into individual stars with his telescope in 1610. Until the early 1920s, most astronomers thought that the Milky Way contained all the stars in the Universe. Following the 1920 Great Debate between the astronomers Harlow Shapley and Heber Curtis, observations by Edwin Hubble showed that the Milky Way is just one of many galaxies. The Milky Way is a barred spiral galaxy with an estimated D25 isophotal diameter of , but only about 1,000 light years thick at the spiral arms (more at the bulg ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tesla (unit)
The tesla (symbol: T) is the unit of magnetic flux density (also called magnetic B-field strength) in the International System of Units (SI). One tesla is equal to one weber per square metre. The unit was announced during the General Conference on Weights and Measures in 1960 and is named in honour of Serbian-American electrical and mechanical engineer Nikola Tesla, upon the proposal of the Slovenian electrical engineer France Avčin. Definition A particle, carrying a charge of one coulomb (C), and moving perpendicularly through a magnetic field of one tesla, at a speed of one metre per second (m/s), experiences a force with magnitude one newton (N), according to the Lorentz force law. That is, : \text = \dfrac. As an SI derived unit, the tesla can also be expressed in terms of other units. For example, a magnetic flux of 1 weber (Wb) through a surface of one square meter is equal to a magnetic flux density of 1 tesla.''The International System of Units (SI), 8th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
BBC Two
BBC Two is a British free-to-air public broadcast television network owned and operated by the BBC. It covers a wide range of subject matter, with a remit "to broadcast programmes of depth and substance" in contrast to the more mainstream and popular BBC One. Like the BBC's other domestic TV and radio channels, it is funded by the television licence, and is therefore free of commercial advertising. It is a comparatively well-funded public-service network, regularly attaining a much higher audience share than most public-service networks worldwide. Originally styled BBC2, it was the third British television station to be launched (starting on 21 April 1964), and from 1 July 1967, Europe's first television channel to broadcast regularly in colour. It was envisaged as a home for less mainstream and more ambitious programming, and while this tendency has continued to date, most special-interest programmes of a kind previously broadcast on BBC Two, for example the BBC Proms, no ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Horizon (British TV Series)
''Horizon'' is an ongoing and long-running British documentary television series on BBC Two that covers science and philosophy. History The programme was first broadcast on 2 May 1964 with "The World of Buckminster Fuller" which explored the theories and structures of inventor Richard Buckminster Fuller and included the ''Horizon'' mission statement: "The aim of ''Horizon'' is to provide a platform from which some of the world's greatest scientists and philosophers can communicate their curiosity, observations and reflections, and infuse into our common knowledge their changing views of the universe". ''Horizon'' continues to be broadcast on BBC Two, and in 2009 added a series of films based on the rich ''Horizon'' archive called ''Horizon Guides'' on BBC Four. In December 2016, it was announced that ''Horizon'' will no longer be made exclusively by the BBC's in-house production division, BBC Studios, and the BBC invited independent production companies to pitch to make episodes ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
_p174_GAINESVILLE%2C_EAST_FLORIDA_SEMINARY.jpg "Click for more on -> University Of Florida")
.jpg "Click for more on -> SQUID")
