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Dead Time
For detection systems that record discrete events, such as particle and nuclear detectors, the dead time is the time after each event during which the system is not able to record another event. An everyday life example of this is what happens when someone takes a photo using a flash – another picture cannot be taken immediately afterward because the flash needs a few seconds to recharge. In addition to lowering the detection efficiency, dead times can have other effects, such as creating possible exploits in quantum cryptography. Overview The total dead time of a detection system is usually due to the contributions of the intrinsic dead time of the detector (for example the ion drift time in a gaseous ionization detector), of the analog front end (for example the shaping time of a spectroscopy amplifier) and of the data acquisition (the conversion time of the analog-to-digital converters and the readout and storage times). The intrinsic dead time of a detector is often due to i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Particle Physics
Particle physics or high-energy physics is the study of Elementary particle, fundamental particles and fundamental interaction, forces that constitute matter and radiation. The field also studies combinations of elementary particles up to the scale of protons and neutrons, while the study of combinations of protons and neutrons is called nuclear physics. The fundamental particles in the universe are classified in the Standard Model as fermions (matter particles) and bosons (force-carrying particles). There are three Generation (particle physics), generations of fermions, although ordinary matter is made only from the first fermion generation. The first generation consists of Up quark, up and down quarks which form protons and neutrons, and electrons and electron neutrinos. The three fundamental interactions known to be mediated by bosons are electromagnetism, the weak interaction, and the strong interaction. Quark, Quarks cannot exist on their own but form hadrons. Hadrons that ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Exponential Distribution
In probability theory and statistics, the exponential distribution or negative exponential distribution is the probability distribution of the distance between events in a Poisson point process, i.e., a process in which events occur continuously and independently at a constant average rate; the distance parameter could be any meaningful mono-dimensional measure of the process, such as time between production errors, or length along a roll of fabric in the weaving manufacturing process. It is a particular case of the gamma distribution. It is the continuous analogue of the geometric distribution, and it has the key property of being memoryless. In addition to being used for the analysis of Poisson point processes it is found in various other contexts. The exponential distribution is not the same as the class of exponential families of distributions. This is a large class of probability distributions that includes the exponential distribution as one of its members, but also includ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Positron Emission Tomography
Positron emission tomography (PET) is a functional imaging technique that uses radioactive substances known as radiotracers to visualize and measure changes in metabolic processes, and in other physiological activities including blood flow, regional chemical composition, and absorption. Different tracers are used for various imaging purposes, depending on the target process within the body, such as: * Fluorodeoxyglucose ( 18F">sup>18FDG or FDG) is commonly used to detect cancer; * 18Fodium fluoride">sup>18Fodium fluoride (Na18F) is widely used for detecting bone formation; * Oxygen-15 (15O) is sometimes used to measure blood flow. PET is a common imaging technique, a medical scintillography technique used in nuclear medicine. A radiopharmaceutical—a radioisotope attached to a drug—is injected into the body as a tracer. When the radiopharmaceutical undergoes beta plus decay, a positron is emitted, and when the positron interacts with an ordinary electron, the tw ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Photomultiplier
A photomultiplier is a device that converts incident photons into an electrical signal. Kinds of photomultiplier include: * Photomultiplier tube, a vacuum tube converting incident photons into an electric signal. Photomultiplier tubes (PMTs for short) are members of the class of vacuum tubes, and more specifically vacuum phototubes, which are extremely sensitive detectors of light in the ultraviolet, visible, and near-infrared ranges of the electromagnetic spectrum. ** Magnetic photomultiplier, developed by the Soviets in the 1930s. ** Electrostatic photomultiplier, a kind of photomultiplier tube demonstrated by Jan Rajchman of RCA Laboratories in Princeton, NJ in the late 1930s which became the standard for all future commercial photomultipliers. The first mass-produced photomultiplier, the Type 931, was of this design and is still commercially produced today. * Silicon photomultiplier, a solid-state device converting incident photons into an electric signal. Silicon photomul ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Allan Variance
The Allan variance (AVAR), also known as two-sample variance, is a measure of frequency stability in clocks, oscillators and amplifiers. It is named after David W. Allan and expressed mathematically as \sigma_y^2(\tau). The Allan deviation (ADEV), also known as sigma-tau, is the square root of the Allan variance, \sigma_y(\tau). The ''M-sample variance'' is a measure of frequency stability using ''M'' samples, time ''T'' between measurements and observation time \tau. ''M''-sample variance is expressed as :\sigma_y^2(M, T, \tau). The Allan variance is intended to estimate stability due to noise processes and not that of systematic errors or imperfections such as frequency drift or temperature effects. The Allan variance and Allan deviation describe frequency stability. See also the section #Interpretation of value, Interpretation of value below. There are also different adaptations or alterations of Allan variance, notably the modified Allan variance MAVAR or MVAR, the total ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Data Acquisition
Data acquisition is the process of sampling signals that measure real-world physical conditions and converting the resulting samples into digital numeric values that can be manipulated by a computer. Data acquisition systems, abbreviated by the acronyms ''DAS,'' ''DAQ,'' or ''DAU,'' typically convert analog waveforms into digital values for processing. The components of data acquisition systems include: * Sensors, to convert physical parameters to electrical signals. * Signal conditioning circuitry, to convert sensor signals into a form that can be converted to digital values. * Analog-to-digital converters, to convert conditioned sensor signals to digital values. Data acquisition applications are usually controlled by software programs developed using various general purpose programming languages such as Assembly, BASIC, C, C++, C#, Fortran, Java, LabVIEW, Lisp, Pascal, etc. Stand-alone data acquisition systems are often called data loggers. There are also ope ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radiation Monitoring
Radiation monitoring involves the measurement of radiation dose or radionuclide contamination for reasons related to the assessment or control of exposure to radiation or radioactive substances, and the interpretation of the results. Environmental monitoring Environmental monitoring is the measurement of external dose rates due to sources in the environment or of radionuclide concentrations in environmental media. Source monitoring Source monitoring is a specific term used in ionising radiation monitoring, and according to the IAEA, is the measurement of activity in radioactive material being released to the environment or of external dose rates due to sources within a facility or activity. In this context a source is anything that may cause radiation exposure — such as by emitting ionising radiation, or releasing radioactive substances. The phrase "standard source" is also used as a de facto term in the more specific context of being a calibration standard source in ionising ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geiger–Müller Tube
The Geiger–Müller tube or G–M tube is the sensing element of the Geiger counter instrument used for the detection of ionizing radiation. It is named after Hans Geiger, who invented the principle in 1908, and Walther Müller, who collaborated with Geiger in developing the technique further in 1928 to produce a practical tube that could detect a number of different radiation types. It is a gaseous ionization detector and uses the Townsend avalanche phenomenon to produce an easily detectable electronic pulse from as little as a single ionizing event due to a radiation particle. It is used for the detection of gamma radiation, X-rays, and alpha and beta particles. It can also be adapted to detect neutrons. The tube operates in the "Geiger" region of ion pair generation. This is shown on the accompanying plot for gaseous detectors showing ion current against applied voltage. While it is a robust and inexpensive detector, the G–M is unable to measure high radiation rates effi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Poisson Process
In probability theory, statistics and related fields, a Poisson point process (also known as: Poisson random measure, Poisson random point field and Poisson point field) is a type of mathematical object that consists of Point (geometry), points randomly located on a Space (mathematics), mathematical space with the essential feature that the points occur independently of one another. The process's name derives from the fact that the number of points in any given finite region follows a Poisson distribution. The process and the distribution are named after French mathematician Siméon Denis Poisson. The process itself was discovered independently and repeatedly in several settings, including experiments on radioactive decay, telephone call arrivals and actuarial science. This point process is used as a mathematical model for seemingly random processes in numerous disciplines including astronomy,G. J. Babu and E. D. Feigelson. Spatial point processes in astronomy. ''Journal of st ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nuclear Physics
Nuclear physics is the field of physics that studies atomic nuclei and their constituents and interactions, in addition to the study of other forms of nuclear matter. Nuclear physics should not be confused with atomic physics, which studies the atom as a whole, including its electrons. Discoveries in nuclear physics have led to applications in many fields such as nuclear power, nuclear weapons, nuclear medicine and magnetic resonance imaging, industrial and agricultural isotopes, ion implantation in materials engineering, and radiocarbon dating in geology and archaeology. Such applications are studied in the field of nuclear engineering. Particle physics evolved out of nuclear physics and the two fields are typically taught in close association. Nuclear astrophysics, the application of nuclear physics to astrophysics, is crucial in explaining the inner workings of stars and the origin of the chemical elements. History The history of nuclear physics as a discipline ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Live Time
Live may refer to: Arts, entertainment, and media Films * ''Live!'' (2007 film), 2007 American film * ''Live'' (2014 film), a 2014 Japanese film * ''Live'' (2023 film), a Malayalam-language film *'' Live: Phát Trực Tiếp'', a Vietnamese-language film * ''Live'' (Apocalyptica DVD) Music *Live (band), American alternative rock band * List of albums titled ''Live'' Extended plays * ''Live EP'' (Anal Cunt album) * ''Live EP'' (Breaking Benjamin EP) * ''Live'' (Roxus EP) * ''Live'' (The Smithereens EP) *''CeCe Peniston (EP Live)'' *''Ozzy Osbourne Live E.P.'', 1980 *''Live EP (Live at Fashion Rocks)'', by David Bowie * ''Live EP'' (The Jam EP) Songs * "Live" (Russian song) * "Live" (Superfly song) * "Live" (The Merry-Go-Round song) *"Live", by B'z from ''Highway X'', 2022 Radio *BBC Radio 5 Live *CILV-FM, branded LiVE 88.5, a radio station in Ottawa, Canada Television * ''Live'' (South Korean TV series), a 2018 South Korean television series *''Live'' (Danish TV series) *Live! ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
