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Neutron Generator
Neutron generators are neutron source devices which contain compact linear particle accelerators and that produce neutrons by fusing isotopes of hydrogen together. The nuclear fusion, fusion reactions take place in these devices by accelerating either deuterium, tritium, or a mixture of these two isotopes into a metal hydride target which also contains deuterium, tritium or a mixture of these isotopes. Fusion of deuterium atoms (D + D) results in the formation of a helium-3 ion and a neutron with a kinetic energy of approximately 2.5 MeV. Fusion of a deuterium and a tritium atom (D + T) results in the formation of a helium-4 ion and a neutron with a kinetic energy of approximately 14.1 MeV. Neutron generators have applications in medicine, security, and materials analysis. The basic concept was first developed by Ernest Rutherford's team in the Cavendish Laboratory in the early 1930s. Using a linear accelerator driven by a Cockcroft–Walton generator, Mark Oliphant l ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Experiment Using An Electronic Neutron Generator
An experiment is a procedure carried out to support or refute a hypothesis, or determine the efficacy or likelihood of something previously untried. Experiments provide insight into Causality, cause-and-effect by demonstrating what outcome occurs when a particular factor is manipulated. Experiments vary greatly in goal and scale but always rely on repeatable procedure and logical analysis of the results. There also exist natural experiment, natural experimental studies. A child may carry out basic experiments to understand how things fall to the ground, while teams of scientists may take years of systematic investigation to advance their understanding of a phenomenon. Experiments and other types of hands-on activities are very important to student learning in the science classroom. Experiments can raise test scores and help a student become more engaged and interested in the material they are learning, especially when used over time. Experiments can vary from personal and i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fusion Power
Fusion power is a proposed form of power generation that would generate electricity by using heat from nuclear fusion reactions. In a fusion process, two lighter atomic nuclei combine to form a heavier nucleus, while releasing energy. Devices designed to harness this energy are known as fusion reactors. Research into fusion reactors began in the 1940s, but as of 2025, no device has reached net power. Fusion processes require fuel, in a state of plasma, and a confined environment with sufficient temperature, pressure, and confinement time. The combination of these parameters that results in a power-producing system is known as the Lawson criterion. In stellar cores the most common fuel is the lightest isotope of hydrogen (Protium (isotope), protium), and gravity provides the conditions needed for fusion energy production. Proposed fusion reactors would use the heavy hydrogen isotopes of deuterium and tritium for DT fusion, for which the Lawson criterion is the easiest to achieve ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kilometer
The kilometre ( SI symbol: km; or ), spelt kilometer in American and Philippine English, is a unit of length in the International System of Units (SI), equal to one thousand metres (kilo- being the SI prefix for ). It is the preferred measurement unit to express distances between geographical places on land in most of the world; notable exceptions are the United States and the United Kingdom where the statute mile is used. Pronunciation There are two common pronunciations for the word. # # The first pronunciation follows a pattern in English whereby SI units are pronounced with the stress on the first syllable (as in kilogram, kilojoule and kilohertz) and the pronunciation of the actual base unit does not change irrespective of the prefix (as in centimetre, millimetre, nanometre and so on). It is generally preferred by the British Broadcasting Corporation (BBC), the Canadian Broadcasting Corporation (CBC), and the Australian Broadcasting Corporation (ABC). Man ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neutron Flux
The neutron flux is a scalar quantity used in nuclear physics and nuclear reactor physics. It is the total distance travelled by all free neutrons per unit time and volume. Equivalently, it can be defined as the number of neutrons travelling through a small sphere of radius R in a time interval, divided by a maximal cross section of the sphere (the great disk area, \pi R^2) and by the duration of the time interval. The dimension of neutron flux is \mathsf^\mathsf^ and the usual unit is cm−2s−1 (reciprocal square centimetre times reciprocal second). The neutron fluence is defined as the neutron flux integrated over a certain time period. So its dimension is \mathsf^ and its usual unit is cm−2 (reciprocal square centimetre). An older term used instead of cm−2 was "n.v.t." (neutrons, velocity, time). Natural neutron flux Neutron flux in asymptotic giant branch stars and in supernovae is responsible for most of the natural nucleosynthesis producing elements heavier th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Field Emission
Field electron emission, also known as field-induced electron emission, field emission (FE) and electron field emission, is the emission of electrons from a material placed in an electrostatic field. The most common context is field emission from a solid surface into a vacuum. However, field emission can take place from solid or liquid surfaces, into a vacuum, a fluid (e.g. air), or any non-conducting or weakly conducting dielectric. The field-induced promotion of electrons from the valence to conduction band of semiconductors (the Zener effect) can also be regarded as a form of field emission. Field emission in pure metals occurs in high electric fields: the gradients are typically higher than 1 gigavolt per metre and strongly dependent upon the work function. While electron sources based on field emission have a number of applications, field emission is most commonly an undesirable primary source of vacuum breakdown and electrical discharge phenomena, which engineers work to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Einzel Lens
An einzel lens (from – single lens), or unipotential lens, is a charged particle electrostatic lens that focuses without changing the energy of the beam. It consists of three or more sets of cylindrical or rectangular apertures or tubes in series along an axis. It is used in ion optics to focus ions in flight, which is accomplished through manipulation of the electric field in the path of the ions. The electrostatic potential in the lens is symmetric, so the ions will regain their initial energy on exiting the lens, although the velocity of the outer particles will be altered such that they converge on to the axis. This causes the outer particles to arrive at the focus intersection slightly later than the ones that travel along a straight path, as they have to travel an extra distance. Theory The equation for the change in radial velocity for a particle as it passes between any pair of cylinders in the lens is: \Delta v_r = \int \frac dz, with ''z'' axis passing through ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mean Free Path
In physics, mean free path is the average distance over which a moving particle (such as an atom, a molecule, or a photon) travels before substantially changing its direction or energy (or, in a specific context, other properties), typically as a result of one or more successive collisions with other particles. Scattering theory Imagine a beam of particles being shot through a target, and consider an infinitesimally thin slab of the target (see the figure). The atoms (or particles) that might stop a beam particle are shown in red. The magnitude of the mean free path depends on the characteristics of the system. Assuming that all the target particles are at rest but only the beam particle is moving, that gives an expression for the mean free path: :\ell = (\sigma n)^, where is the mean free path, is the number of target particles per unit volume, and is the effective cross-sectional area for collision. The area of the slab is , and its volume is . The typical number of s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Torr
The torr (symbol: Torr) is a Pressure#Units, unit of pressure based on an absolute scale, defined as exactly of a standard atmosphere (unit), atmosphere (101325 Pa). Thus one torr is exactly (≈ ). Historically, one torr was intended to be the same as one "millimetre of mercury", but subsequent redefinitions of the two units of measurement, units made the torr marginally lower (by less than 0.000015%). The torr is not part of the International System of Units (SI). Even so, it is often combined with the metric prefix milli to name one millitorr (mTorr), equal to 0.001 Torr. The unit was named after Evangelista Torricelli, an Italian physicist and mathematician who discovered the principle of the barometer in 1644. Nomenclature and common errors The unit name ''torr'' is written in letter case, lower case, while its symbol ("Torr") is always written with an uppercase initial; including in combinations with prefixes and other unit symbols, as in "mTorr" (millitorr) or " ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Momentum
In Newtonian mechanics, momentum (: momenta or momentums; more specifically linear momentum or translational momentum) is the product of the mass and velocity of an object. It is a vector quantity, possessing a magnitude and a direction. If is an object's mass and is its velocity (also a vector quantity), then the object's momentum (from Latin '' pellere'' "push, drive") is: \mathbf = m \mathbf. In the International System of Units (SI), the unit of measurement of momentum is the kilogram metre per second (kg⋅m/s), which is dimensionally equivalent to the newton-second. Newton's second law of motion states that the rate of change of a body's momentum is equal to the net force acting on it. Momentum depends on the frame of reference, but in any inertial frame of reference, it is a ''conserved'' quantity, meaning that if a closed system is not affected by external forces, its total momentum does not change. Momentum is also conserved in special relativity (with a mo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Laboratory Frame Of Reference
In theoretical physics, a local reference frame (local frame) refers to a coordinate system or frame of reference that is only expected to function over a small region or a restricted region of space or spacetime. The term is most often used in the context of the application of local inertial frames to small regions of a gravitational field. Although gravitational tidal forces will cause the background geometry to become noticeably non-Euclidean over larger regions, if we restrict ourselves to a sufficiently small region containing a cluster of objects falling together in an ''effectively'' uniform gravitational field, their physics can be described as the physics of that cluster in a space free from explicit background gravitational effects. Equivalence principle When constructing his general theory of relativity, Einstein made the following observation: a freely falling object in a gravitational field will not be able to detect the existence of the field by making local meas ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Center-of-momentum Frame
In physics, the center-of-momentum frame (COM frame) of a system, also known as zero-momentum frame, is the inertial frame in which the total momentum of the system vanishes. It is unique up to velocity, but not origin. The ''center of momentum'' of a system is not a location, but a collection of relative momenta/velocities: a reference frame. Thus "center of momentum" is a short for "center-of-momentum ".Dynamics and Relativity, J.R. Forshaw, A.G. Smith, Wiley, 2009, A special case of the center-of-momentum frame is the center-of-mass frame: an inertial frame in which the center of mass (which is a single point) remains at the origin. In all center-of-momentum frames, the center of mass is at rest, but it is not necessarily at the origin of the coordinate system. In special relativity, only when the system is isolated is the COM frame necessarily unique. Properties General The center of momentum frame is defined as the inertial frame in which the sum of the linear momen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Isotropy
In physics and geometry, isotropy () is uniformity in all orientations. Precise definitions depend on the subject area. Exceptions, or inequalities, are frequently indicated by the prefix ' or ', hence ''anisotropy''. ''Anisotropy'' is also used to describe situations where properties vary systematically, dependent on direction. Isotropic radiation has the same intensity regardless of the direction of measurement, and an isotropic field exerts the same action regardless of how the test particle is oriented. Mathematics Within mathematics, ''isotropy'' has a few different meanings: ; Isotropic manifolds: A manifold is isotropic if the geometry on the manifold is the same regardless of direction. A similar concept is homogeneity. ; Isotropic quadratic form: A quadratic form ''q'' is said to be isotropic if there is a non-zero vector ''v'' such that ; such a ''v'' is an isotropic vector or null vector. In complex geometry, a line through the origin in the direction of an is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
