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Relativistic Particle
In particle physics, a relativistic particle is an elementary particle with kinetic energy greater than or equal to its rest-mass energy given by Einstein's relation, E=m_0c^2, or specifically, of which the velocity is comparable to the speed of light c. This is achieved by photons to the extent that effects described by special relativity are able to describe those of such particles themselves. Several approaches exist as a means of describing the motion of single and multiple relativistic particles, with a prominent example being postulations through the Dirac equation of single particle motion. Since the energy-momentum relation of an particle can be written as: where E is the energy, p is the momentum, and m_0 is the rest mass, when the rest mass tends to be zero, e.g. for a photon, or the momentum tends to be large, e.g. for a large-speed proton, this relation will collapses into a linear dispersion, i.e. This is different from the parabolic energy-momentum relation fo ... [...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] |
Relativistic Plasma
Relativistic plasmas in physics are plasmas for which relativistic corrections to a particle's mass and velocity are important. Such corrections typically become important when a significant number of electrons reach speeds greater than 0.86 c (Lorentz factor \gamma=2). Such plasmas may be created either by heating a gas to very high temperatures or by the impact of a high-energy particle beam. A relativistic plasma with a thermal distribution function has temperatures greater than around 260 keV, or 3.0 GK (5.5 billion degrees Fahrenheit), where approximately 10% of the electrons have \gamma > 2. Since these temperatures are so high, most relativistic plasmas are small and brief, and are often the result of a relativistic beam impacting some target. (More mundanely, "relativistic plasma" might denote a normal, cold plasma moving at a significant fraction of the speed of light relative to the observer.) Relativistic plasmas may result when two particle beams collide at speed ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Relativistic Beaming
In physics, relativistic beaming (also known as Doppler beaming, Doppler boosting, or the headlight effect) is the process by which relativistic effects modify the apparent luminosity of emitting matter that is moving at speeds close to the speed of light. In an astronomical context, relativistic beaming commonly occurs in two oppositely-directed relativistic jets of plasma that originate from a central compact object that is accreting matter. Accreting compact objects and relativistic jets are invoked to explain x-ray binaries, gamma-ray bursts, and, on a much larger scale, (AGN) active galactic nuclei (of which quasars are a particular variety). Beaming affects the apparent brightness of a moving object. Consider a cloud of gas moving relative to the observer and emitting electromagnetic radiation. If the gas is moving towards the observer, it will be brighter than if it were at rest, but if the gas is moving away, it will appear fainter. The magnitude of the effect ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Relativistic Jet
An astrophysical jet is an astronomical phenomenon where outflows of ionised matter are emitted as extended beams along the axis of rotation. When this greatly accelerated matter in the beam approaches the speed of light, astrophysical jets become relativistic jets as they show effects from special relativity. The formation and powering of astrophysical jets are highly complex phenomena that are associated with many types of high-energy astronomical sources. They likely arise from dynamic interactions within accretion disks, whose active processes are commonly connected with compact central objects such as black holes, neutron stars or pulsars. One explanation is that tangled magnetic fields are organised to aim two diametrically opposing beams away from the central source by angles only several degrees wide Jets may also be influenced by a general relativity effect known as frame-dragging. Most of the largest and most active jets are created by supermassive black holes (SMBH) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Relativistic Plasma
Relativistic plasmas in physics are plasmas for which relativistic corrections to a particle's mass and velocity are important. Such corrections typically become important when a significant number of electrons reach speeds greater than 0.86 c (Lorentz factor \gamma=2). Such plasmas may be created either by heating a gas to very high temperatures or by the impact of a high-energy particle beam. A relativistic plasma with a thermal distribution function has temperatures greater than around 260 keV, or 3.0 GK (5.5 billion degrees Fahrenheit), where approximately 10% of the electrons have \gamma > 2. Since these temperatures are so high, most relativistic plasmas are small and brief, and are often the result of a relativistic beam impacting some target. (More mundanely, "relativistic plasma" might denote a normal, cold plasma moving at a significant fraction of the speed of light relative to the observer.) Relativistic plasmas may result when two particle beams collide at speed ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Relativistic Mass
The word "mass" has two meanings in special relativity: ''invariant mass'' (also called rest mass) is an invariant quantity which is the same for all observers in all reference frames, while the relativistic mass is dependent on the velocity of the observer. According to the concept of mass–energy equivalence, invariant mass is equivalent to '' rest energy'', while relativistic mass is equivalent to '' relativistic energy'' (also called total energy). The term "relativistic mass" tends not to be used in particle and nuclear physics and is often avoided by writers on special relativity, in favor of referring to the body's relativistic energy. In contrast, "invariant mass" is usually preferred over rest energy. The measurable inertia of a body in a given frame of reference is determined by its relativistic mass, not merely its invariant mass. For example, photons have zero rest mass but contribute to the inertia (and weight in a gravitational field) of any system containing th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Relativistic Wave Equations
In physics, specifically relativistic quantum mechanics (RQM) and its applications to particle physics, relativistic wave equations predict the behavior of particles at high energies and velocities comparable to the speed of light. In the context of quantum field theory (QFT), the equations determine the dynamics of quantum fields. The solutions to the equations, universally denoted as or (Greek psi), are referred to as "wave functions" in the context of RQM, and " fields" in the context of QFT. The equations themselves are called "wave equations" or "field equations", because they have the mathematical form of a wave equation or are generated from a Lagrangian density and the field-theoretic Euler–Lagrange equations (see classical field theory for background). In the Schrödinger picture, the wave function or field is the solution to the Schrödinger equation, i\hbar\frac\psi = \hat \psi, one of the postulates of quantum mechanics. All relativistic wave equations ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Special Relativity
In physics, the special theory of relativity, or special relativity for short, is a scientific theory of the relationship between Spacetime, space and time. In Albert Einstein's 1905 paper, Annus Mirabilis papers#Special relativity, "On the Electrodynamics of Moving Bodies", the theory is presented as being based on just Postulates of special relativity, two postulates: # The laws of physics are Invariant (physics), invariant (identical) in all Inertial frame of reference, inertial frames of reference (that is, Frame of reference, frames of reference with no acceleration). This is known as the principle of relativity. # The speed of light in vacuum is the same for all observers, regardless of the motion of light source or observer. This is known as the principle of light constancy, or the principle of light speed invariance. The first postulate was first formulated by Galileo Galilei (see ''Galilean invariance''). Background Special relativity builds upon important physics ide ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ultrarelativistic Limit
In physics, a particle is called ultrarelativistic when its speed is very close to the speed of light . Notations commonly used are v \approx c or \beta \approx 1 or \gamma \gg 1 where \gamma is the Lorentz factor, \beta = v/c and c is the speed of light. The energy of an ultrarelativistic particle is almost completely due to its kinetic energy E_k = (\gamma - 1) m c^2. The total energy can also be approximated as E = \gamma m c^2 \approx pc where p = \gamma m v is the Lorentz invariant momentum. This can result from holding the mass fixed and increasing the kinetic energy to very large values or by holding the energy fixed and shrinking the mass to very small values which also imply a very large \gamma. Particles with a very small mass do not need much energy to travel at a speed close to c. The latter is used to derive orbits of massless particles such as the photon from those of massive particles (cf. Kepler problem in general relativity). Ultrarelativistic approximations ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transition Radiation Detector
A transition radiation detector (TRD) is a particle detector using the Lorentz factor (\gamma)-dependent threshold of transition radiation in a stratified material. It contains many layers of materials with different indices of refraction. At each interface between materials, the probability of transition radiation increases with the relativistic gamma factor. Thus, particles with large \gamma give off many photons, and small \gamma give off few. For a given energy, this allows a discrimination between a lighter particle (which has a high \gamma and therefore radiates) and a heavier particle (which has a low \gamma and radiates much less). The passage of the particle is observed through many thin layers of material put in air or gas. The radiated X-ray photon gives energy deposition by the photoelectric effect, and the signal is detected as ionization. Usually, materials with low atomic number Z are preferred (Li, Be) for the radiator, while for photons materials with high Z are u ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transition Radiation
Transition radiation (TR) is a form of electromagnetic radiation emitted when a charged particle passes through inhomogeneous media, such as a boundary between two different media. This is in contrast to Cherenkov radiation, which occurs when a charged particle passes through a homogeneous dielectric medium at a speed greater than the phase velocity of electromagnetic waves in that medium. History Transition radiation was demonstrated theoretically by Ginzburg and Frank in 1945. They showed the existence of transition radiation when a charged particle perpendicularly passed through a boundary between two different homogeneous media. The frequency of radiation emitted in the backwards direction relative to the particle was mainly in the range of visible light. The intensity of radiation was proportional to the logarithm of the Lorentz factor of the particle. After the first observation of the transition radiation in the optical region, many early studies indicated that the applicati ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dielectric Constant
The relative permittivity (in older texts, dielectric constant) is the permittivity of a material expressed as a ratio with the electric permittivity of a vacuum. A dielectric is an insulating material, and the dielectric constant of an insulator measures the ability of the insulator to store electric energy in an electrical field. Permittivity is a material's property that affects the Coulomb force between two point charges in the material. Relative permittivity is the factor by which the electric field between the charges is decreased relative to vacuum. Likewise, relative permittivity is the ratio of the capacitance of a capacitor using that material as a dielectric, compared with a similar capacitor that has vacuum as its dielectric. Relative permittivity is also commonly known as the dielectric constant, a term still used but deprecated by standards organizations in engineering as well as in chemistry. Definition Relative permittivity is typically denoted as (som ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
