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STAR Experiment
The STAR detector (for Solenoidal Tracker at RHIC) is one of the four experiments at the Relativistic Heavy Ion Collider (RHIC) in Brookhaven National Laboratory, United States. The primary scientific objective of STAR is to study the formation and characteristics of the quark–gluon plasma (QGP), a state of matter believed to exist at sufficiently high energy densities. Detecting and understanding the QGP allows physicists to understand better the Universe in the seconds after the Big Bang, when the presently-observed symmetries (and asymmetries) of the Universe were established. Unlike other physics experiments where a theoretical prediction can be tested directly by a single measurement, STAR must make use of a variety of simultaneous studies in order to draw strong conclusions about the QGP. This is due both to the complexity of the system formed in the high-energy nuclear collision and the unexplored landscape of the physics studied. STAR therefore consists of several types ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
STAR Detector At Relativistic Heavy Ion Collider
A star is an astronomical object comprising a luminous spheroid of plasma (physics), plasma held together by its gravity. The List of nearest stars and brown dwarfs, nearest star to Earth is the Sun. Many other stars are visible to the naked eye at night sky, night, but their immense distances from Earth make them appear as fixed stars, fixed points of light. The most prominent stars have been categorised into constellations and asterism (astronomy), asterisms, and many of the brightest stars have proper names. Astronomers have assembled star catalogues that identify the known stars and provide standardized stellar designations. The observable universe contains an estimated to stars. Only about 4,000 of these stars are visible to the naked eye, all within the Milky Way galaxy. A star's life star formation, begins with the gravitational collapse of a gaseous nebula of material composed primarily of hydrogen, along with helium and trace amounts of heavier elements. Its stellar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Viscosity
The viscosity of a fluid is a measure of its resistance to deformation at a given rate. For liquids, it corresponds to the informal concept of "thickness": for example, syrup has a higher viscosity than water. Viscosity quantifies the internal frictional force between adjacent layers of fluid that are in relative motion. For instance, when a viscous fluid is forced through a tube, it flows more quickly near the tube's axis than near its walls. Experiments show that some stress (such as a pressure difference between the two ends of the tube) is needed to sustain the flow. This is because a force is required to overcome the friction between the layers of the fluid which are in relative motion. For a tube with a constant rate of flow, the strength of the compensating force is proportional to the fluid's viscosity. In general, viscosity depends on a fluid's state, such as its temperature, pressure, and rate of deformation. However, the dependence on some of these properties is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vacuum Birefringence
A vacuum is a space devoid of matter. The word is derived from the Latin adjective ''vacuus'' for "vacant" or "void". An approximation to such vacuum is a region with a gaseous pressure much less than atmospheric pressure. Physicists often discuss ideal test results that would occur in a ''perfect'' vacuum, which they sometimes simply call "vacuum" or free space, and use the term partial vacuum to refer to an actual imperfect vacuum as one might have in a laboratory or in space. In engineering and applied physics on the other hand, vacuum refers to any space in which the pressure is considerably lower than atmospheric pressure. The Latin term ''in vacuo'' is used to describe an object that is surrounded by a vacuum. The ''quality'' of a partial vacuum refers to how closely it approaches a perfect vacuum. Other things equal, lower gas pressure means higher-quality vacuum. For example, a typical vacuum cleaner produces enough suction to reduce air pressure by around 20%. But high ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Breit–Wheeler Process
The Breit–Wheeler process or Breit–Wheeler pair production is a physical process in which a positron–electron pair is created from the collision of two photons. It is the simplest mechanism by which pure light can be potentially transformed into matter. The process can take the form γ γ′ → e+ e− where γ and γ′ are two light quanta (for example, gamma ray, gamma photons). The multiphoton Breit–Wheeler process, also referred to as nonlinear Breit–Wheeler or strong field Breit–Wheeler in the literature, is the extension of the pure photon–photon Breit–Wheeler process when a high-energy probe photon decays into pairs propagating through an electromagnetic field (for example, a laser pulse). In contrast with the previous process, this one can take the form of γ + n ω → e+ e−, where ω represents the coherent photons of the laser field. The inverse process, e+ e− → γ γ′, in which an electron and a positron collide and annihilate to generate a p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
John Harris (physicist)
John William Harris (born March 14, 1950) is an American experimental high energy nuclear physicist and D. Allan Bromley Professor of Physics at Yale University. His research interests are focused on understanding high energy density QCD and the quark–gluon plasma created in relativistic collisions of heavy ions. Dr. Harris collaborated on the original proposal to initiate a high energy heavy ion program at Cern in Geneva, Switzerland, has been actively involved in the CERN heavy ion program and was the founding spokesperson for the STAR collaboration at RHIC at Brookhaven National Laboratory in the U.S. Nuclear Physics career After obtaining a Bachelor of Science, with Distinction, from the University of Washington, John Harris started his career at the Stony Brook University (then known as State University of New York at Stony Brook), where he completed his Ph.D. in experimental nuclear physics in 1978. Lawrence Berkeley National Laboratory After his Ph.D. Dr. Harris went to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Olga Evdokimov
Olga Evdokimov is a Russian born professor of physics at the University of Illinois, Chicago (UIC). She is a High Energy Nuclear Physicist, who currently collaborates on two international experiments; the Solenoidal Tracker At RHIC (STAR) experiment at the Relativistic Heavy Ion Collider (RHIC), Brookhaven National Laboratory, Upton, New York and the Compact Muon Solenoid (CMS) experiment at the LHC (Large Hadron Collider), CERN, Geneva, Switzerland. Education Evdokimov obtained both her MS in theoretical physics in 1996 and her Ph.D. in Physical & Mathematical Sciences in 1999 from the Ivanovo State University, Ivanovo, Russia. She performed her Ph.D. research at Laboratory for High Energy Physics at Joint Institute for Nuclear Research, Dubna, Russia. Her thesis was titled "Alignment and Fast Algorithms of Data Treatment for 4π-geometry Detectors." Career Evdokimov worked first as a post-doctoral researcher at Purdue University. In 2005 she joined UIC as an Adjunct ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Helen Caines
Helen Louise Caines is a Professor of Physics at Yale University. She studies the quark–gluon plasma and is the co-spokesperson for the STAR experiment. Education Caines studied physics at the University of Birmingham and graduated in 1992. She earned her PhD at the University of Birmingham in 1996. Career and research In 1996 she joined Ohio State University. She was elected a junior representative of the STAR experiment in 1998. Caines was appointed to Yale University in 2004. She studies the quark–gluon plasma, working alongside John Harris. She uses heavy-ion experiments to study quantum chromodynamics in extreme conditions. She studies the quark–gluon plasma. Her measurements indicated the quark–gluon plasma is the most vortical fluid ever known. In 2005 she became a council member of the STAR experiment advisory board. She investigated soft physics. She was elected a fellow of the Institute of Physics in 2008. She was promoted to Associate Professor with tenu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chiral Magnetic Effect
Chiral magnetic effect (CME) is the generation of electric current along an external magnetic field induced by chirality imbalance. Fermions are said to be chiral if they keep a definite projection of spin quantum number on momentum. The CME is a macroscopic quantum phenomenon present in systems with charged chiral fermions, such as the quark–gluon plasma, or Dirac and Weyl semimetals. The CME is a consequence of chiral anomaly in quantum field theory; unlike conventional superconductivity or superfluidity, it does not require a spontaneous symmetry breaking. The chiral magnetic current is non-dissipative, because it is topologically protected: the imbalance between the densities of left-handed and right-handed chiral fermions is linked to the topology of fields in gauge theory by the Atiyah-Singer index theorem. The experimental observation of CME in a Dirac semimetal ZrTe5 was reported in 2014 by a group from Brookhaven National Laboratory and Stony Brook University. The mate ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Macroscopic Quantum Phenomena
Macroscopic quantum phenomena are processes showing quantum behavior at the macroscopic scale, rather than at the atomic scale where quantum effects are prevalent. The best-known examples of macroscopic quantum phenomena are superfluidity and superconductivity; other examples include the quantum Hall effect and topological order. Since 2000 there has been extensive experimental work on quantum gases, particularly Bose–Einstein condensates. Between 1996 and 2016 six Nobel Prizes were given for work related to macroscopic quantum phenomena. Macroscopic quantum phenomena can be observed in superfluid helium and in superconductors, but also in dilute quantum gases, dressed photons such as polaritons and in laser light. Although these media are very different, they are all similar in that they show macroscopic quantum behavior, and in this respect they all can be referred to as quantum fluids. Quantum phenomena are generally classified as macroscopic when the quantum states are oc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Elliptic Flow
Relativistic heavy-ion collisions produce very large numbers of subatomic particles in all directions. In such collisions, ''flow'' refers to how energy, momentum, and number of these particles varies with direction, and elliptic flow is a measure of how the flow is not uniform in all directions when viewed along the beam-line. Elliptic flow is strong evidence for the existence of quark–gluon plasma, and has been described as one of the most important observations measured at the Relativistic Heavy Ion Collider (RHIC). Elliptic flow describes the azimuthal momentum space anisotropy of particle emission from non-central heavy-ion collisions in the plane transverse to the beam direction, and is defined as the second harmonic coefficient of the azimuthal Fourier decomposition of the momentum distribution. Elliptic flow is a fundamental observable since it directly reflects the initial spatial anisotropy, of the nuclear overlap region in the transverse plane, directly translated in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Relativistic Heavy Ion Collider
The Relativistic Heavy Ion Collider (RHIC ) is the first and one of only two operating heavy-ion colliders, and the only spin-polarized proton collider ever built. Located at Brookhaven National Laboratory (BNL) in Upton, New York, and used by an international team of researchers, it is the only operating particle collider in the US. By using RHIC to collide ions traveling at relativistic speeds, physicists study the primordial form of matter that existed in the universe shortly after the Big Bang. By colliding spin-polarized protons, the spin structure of the proton is explored. RHIC is as of 2019 the second-highest-energy heavy-ion collider in the world. As of November 7, 2010, the Large Hadron Collider (LHC) has collided heavy ions of lead at higher energies than RHIC. The LHC operating time for ions (lead–lead and lead–proton collisions) is limited to about one month per year. In 2010, RHIC physicists published results of temperature measurements from earlier experime ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hadrons
In particle physics, a hadron (; grc, ἁδρός, hadrós; "stout, thick") is a composite subatomic particle made of two or more quarks held together by the strong interaction. They are analogous to molecules that are held together by the electric force. Most of the mass of ordinary matter comes from two hadrons: the proton and the neutron, while most of the mass of the protons and neutrons is in turn due to the binding energy of their constituent quarks, due to the strong force. Hadrons are categorized into two broad families: baryons, made of an odd number of quarks (usually three quarks) and mesons, made of an even number of quarks (usually two quarks: one quark and one antiquark). Protons and neutrons (which make the majority of the mass of an atom) are examples of baryons; pions are an example of a meson. "Exotic" hadrons, containing more than three valence quarks, have been discovered in recent years. A tetraquark state (an exotic meson), named the Z(4430), was discove ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
