FACTOID # 10: The total number of state executions in 2005 was 60: 19 in Texas and 41 elsewhere. The racial split was 19 Black and 41 White.

 Home Encyclopedia Statistics States A-Z Flags Maps FAQ About

 WHAT'S NEW RELATED ARTICLES People who viewed "Neutron" also viewed:

SEARCH ALL

Search encyclopedia, statistics and forums:

(* = Graphable)

Encyclopedia > Neutron
Neutron
Classification
 Subatomic particle Fermion Hadron Baryon Nucleon Neutron
Properties [1][2]
 Mass: 1.674 927 29(28) × 10−27 kg 939.565 560(81) MeV/c² 1.008665 amu Radius: about 0.8 × 10−15 m Electric charge: 0 C Spin: ½ Magnetic dipole moment: −1.91304273(45) μN Quark composition: 2 Down, 1 Up

In physics, the neutron is a subatomic particle with no net electric charge and a mass of 939.573 MeV/c² (1.6749 × 10−27 kg, slightly more than a proton). Its spin is ½. Its antiparticle is called the antineutron. The neutron, along with the proton, is a nucleon. Neutron, the subatomic particle, may also refer to: Neutron (comics), a Marvel Comics character. ... A free neutron is a neutron that exists outside of an atomic nucleus. ... A subatomic particle is a particle smaller than an atom: it may be elementary or composite. ... In particle physics, fermions are particles with half-integer spin. ... In particle physics, a hadron is a subatomic particle which experiences the strong nuclear force. ... In particle physics, the baryons are a family of subatomic particles including the proton and the neutron (collectively called nucleons), as well as a number of unstable, heavier particles (called hyperons). ... In physics a nucleon is a collective name for two baryons: the neutron and the proton. ... An electronvolt (symbol: eV) is the amount of energy gained by a single unbound electron when it falls through an electrostatic potential difference of one volt. ... A line showing the speed of light on a scale model of Earth and the Moon The speed of light in a vacuum is an important physical constant denoted by the letter c for constant or the Latin word celeritas meaning swiftness. It is the speed of all electromagnetic radiation... The unified atomic mass unit (u), or Dalton (Da), is a small unit of mass used to express atomic and molecular masses. ... The coulomb (symbol: C) is the SI unit of electric charge. ... These are the 6 quarks and their most likely decay modes. ... Image File history File links Quark_structure_neutron. ... Physics (Greek: (phÃºsis), nature and (phusikÃ©), knowledge of nature) is the science concerned with the fundamental laws of the universe and their precise formulation in a mathematical framework. ... A subatomic particle is a particle smaller than an atom: it may be elementary or composite. ... Electric charge is a fundamental conserved property of some subatomic particles, which determines their electromagnetic interaction. ... Unsolved problems in physics: What causes anything to have mass? The U.S. National Prototype Kilogram, which currently serves as the primary standard for measuring mass in the U.S. Mass is the property of a physical object that quantifies the amount of matter and energy it is equivalent to. ... An electronvolt (symbol: eV) is the amount of energy gained by a single unbound electron when it falls through an electrostatic potential difference of one volt. ... A line showing the speed of light on a scale model of Earth and the Moon The speed of light in a vacuum is an important physical constant denoted by the letter c for constant or the Latin word celeritas meaning swiftness. It is the speed of all electromagnetic radiation... // Properties [1][2] In physics, the proton (Greek proton = first) is a subatomic particle with an electric charge of one positive fundamental unit (1. ... In physics, spin refers to the angular momentum intrinsic to a body, as opposed to orbital angular momentum, which is the motion of its center of mass about an external point. ... Corresponding to most kinds of particle, there is an associated antiparticle with the same mass and opposite charges. ... The antineutron is the antiparticle of the neutron. ... In physics a nucleon is a collective name for two baryons: the neutron and the proton. ...

The nucleus of most atoms (all stable isotopes except the most common isotope of hydrogen, protium, which consists of a single proton only) consists of protons and neutrons. The number of neutrons determines the isotope of an element. (For example, the carbon-12 isotope has 6 protons and 6 neutrons, while the carbon-14 isotope has 6 protons and 8 neutrons.) Isotopes are atoms of the same element that have the same atomic number but different masses due to a different number of neutrons. A semi-accurate depiction of the helium atom. ... â€œAtomicâ€ redirects here. ... This article needs to be cleaned up to conform to a higher standard of quality. ... Isotopes are any of the several different forms of an element each having different atomic mass (mass number). ... This article is about the chemistry of hydrogen. ... Isotopes are any of the several different forms of an element each having different atomic mass (mass number). ... Carbon 12 is a stable isotope of the element carbon. ... Carbon-14 is the radioactive isotope of carbon discovered February 27, 1940, by Martin Kamen and Sam Ruben. ...

A neutron consists of two down quarks and one up quark, thus classifying it as a baryon. These are the 6 quarks and their most likely decay modes. ... These are the 6 quarks and their most likely decay modes. ... In particle physics, the baryons are a family of subatomic particles including the proton and the neutron (collectively called nucleons), as well as a number of unstable, heavier particles (called hyperons). ...

## Stability

The Feynmann diagram of the neutron beta decay process

Outside the nucleus, free neutrons are unstable and have a mean lifetime of 885.7±0.8 seconds (about 15 minutes), decaying by emitting an electron and antineutrino to become a proton:[1] Image File history File links No higher resolution available. ... Image File history File links No higher resolution available. ... In this Feynman diagram, an electron and positron annihilate producing a virtual photon that becomes a quark-antiquark pair. ... In nuclear physics, beta decay (sometimes called neutron decay) is a type of radioactive decay in which a beta particle (an electron or a positron) is emitted. ... A free neutron is a neutron that exists outside of an atomic nucleus. ... Given an assembly of elements, the number of which decreases ultimately to zero, the lifetime (also called the mean lifetime) is a certain number that characterizes the rate of reduction (decay) of the assembly. ... e- redirects here. ... Neutrinos are elementary particles. ...

$hbox{n}tohbox{p}+hbox{e}^-+overline{nu}_{mathrm{e}}$

This decay mode, known as beta decay, can also occur within certain unstable nuclei. Protons can also transform into neutrons through the process of electron capture, sometimes called inverse beta decay. Both beta decay and electron capture are types of radioactive decay. In nuclear physics, beta decay (sometimes called neutron decay) is a type of radioactive decay in which a beta particle (an electron or a positron) is emitted. ... Electron capture is a decay mode for isotopes that will occur when there are too many protons in the nucleus of an atom, and there isnt enough energy to emit a positron; however, it continues to be a viable decay mode for radioactive isotopes that can decay by positron... OK : Radioactive and Radioactivity redirect here. ...

Particles inside the nucleus are typically resonances between neutrons and protons, which transform into one another by the emission and absorption of pions. This article is about resonance in physics. ... In particle physics, pion (short for pi meson) is the collective name for three subatomic particles: Ï€0, Ï€+ and Ï€âˆ’. Pions are the lightest mesons and play an important role in explaining low-energy properties of the strong nuclear force. ...

## Interactions

The neutron interacts through all four fundamental interactions: the electromagnetic, weak nuclear, strong nuclear and gravitational interactions. A fundamental interaction is a mechanism by which particles interact with each other, and which cannot be explained by another more fundamental interaction. ... Electromagnetic interaction is a fundamental force of nature and is felt by charged leptons and quarks. ... The weak interaction (often called the weak force or sometimes the weak nuclear force) is one of the four fundamental interactions of nature. ... The strong interaction or strong force is today understood to represent the interactions between quarks and gluons as detailed by the theory of quantum chromodynamics (QCD). ... â€œGravityâ€ redirects here. ...

Although the neutron has zero net charge, it may interact electromagnetically in two ways: first, the neutron has a magnetic moment of the same order as the proton; second, it is composed of electrically charged quarks. Thus, the electromagnetic interaction is primarily important to the neutron in deep inelastic scattering and in magnetic interactions. A bar magnet. ... // Properties [1][2] In physics, the proton (Greek proton = first) is a subatomic particle with an electric charge of one positive fundamental unit (1. ... These are the 6 quarks and their most likely decay modes. ... Deep Inelastic Scattering is the name given to a process used to probe the insides of hadrons (particularly the baryons, such as protons and neutrons), using electrons. ... Magnetic lines of force of a bar magnet shown by iron filings on paper In physics, magnetism is one of the phenomena by which materials exert an attractive or repulsive force on other materials. ...

The neutron experiences the weak interaction through beta decay into a proton, electron and electron antineutrino. It experiences the gravitational force as does any energetic body; however, gravity is so weak that it may be neglected in most particle physics experiments. In nuclear physics, beta decay (sometimes called neutron decay) is a type of radioactive decay in which a beta particle (an electron or a positron) is emitted. ... e- redirects here. ... Neutrinos are elementary particles. ... Thousands of particles explode from the collision point of two relativistic (100 GeV per ion) gold ions in the STAR detector of the Relativistic Heavy Ion Collider. ...

The most important force to neutrons is the strong interaction. This interaction is responsible for the binding of the neutron's three quarks (one up quark, two down quarks) into a single particle. The residual strong force is also responsible for the binding of nuclei: the nuclear force. The nuclear force plays the leading role when neutrons pass through matter. Unlike charged particles or photons, the neutron cannot lose energy by ionizing atoms. Rather, the neutron goes on its way unchecked until it makes a head-on collision with an atomic nucleus. For this reason, neutron radiation is extremely penetrating and dangerous. These are the 6 quarks and their most likely decay modes. ... The up quark is a first-generation quark with a charge of +(2/3)e. ... The down quark is a first-generation quark with a charge of -(1/3)e. ... This article is about the force sometimes called the strong nuclear force. For the weak nuclear force or weak interaction, see that article. ... A semi-accurate depiction of the helium atom. ... The nuclear force (or nucleon-nucleon interaction or residual strong force) is the force between two or more nucleons. ... Ionization is the physical process of converting an atom or molecule into an ion by changing the difference between the number of protons and electrons. ... Neutron radiation consists of free neutrons. ...

## Detection

Main article: neutron detection

The common means of detecting a charged particle by looking for a track of ionization (such as in a cloud chamber) does not work for neutrons directly. Neutrons that elastically scatter off atoms can create an ionization track that is detectable, but the experiments are not as simple to carry out; other means for detecting neutrons, consisting of allowing them to interact with atomic nuclei, are more commonly used. Neutron detection is the effective detection of neutrons entering a well-positioned laboratory detector. ... Electric charge is a fundamental conserved property of some subatomic particles, which determines their electromagnetic interaction. ... In particle physics, an elementary particle or fundamental particle is a particle not known to have substructure; that is, it is not made up of smaller particles. ... Discovery of the positron in 1932 by Carl D. Anderson in a cloud chamber The cloud chamber, also known as the Wilson chamber, is used for detecting particles of ionizing radiation. ...

A common method for detecting neutrons involves converting the energy released from such reactions into electrical signals. The nuclides 3He, 6Li, 10B, 233U, 235U, 237Np and 239Pu are useful for this purpose. A good discussion on neutron detection is found in chapter 14 of the book Radiation Detection and Measurement by Glenn F. Knoll (John Wiley & Sons, 1979).

## Uses

The neutron plays an important role in many nuclear reactions. For example, neutron capture often results in neutron activation, inducing radioactivity. In particular, knowledge of neutrons and their behavior has been important in the development of nuclear reactors and nuclear weapons. Neutron activation is the process by which neutron radiation induces radioactivity in materials. ... Radioactivity may mean: Look up radioactivity in Wiktionary, the free dictionary. ... Core of a small nuclear reactor used for research. ... The mushroom cloud of the atomic bombing of Nagasaki, Japan, 1945, rose some 18 kilometers (11 mi) above the hypocenter. ...

Cold, thermal and hot neutron radiation is commonly employed in neutron scattering facilities, where the radiation is used in a similar way one uses X-rays for the analysis of condensed matter. Neutrons are complementary to the latter in terms of atomic contrasts by different scattering cross sections; sensitivity to magnetism; energy range for inelastic neutron spectroscopy; and deep penetration into matter. The neutron temperature indicates a free neutrons energy, usually given in electron volts. ... Neutron radiation consists of free neutrons. ... The term Neutron Scattering encompasses all scientific techniques whereby neutrons are used as a scientific probe. ... In the NATO phonetic alphabet, X-ray represents the letter X. An X-ray picture (radiograph) taken by Röntgen An X-ray is a form of electromagnetic radiation with a wavelength approximately in the range of 5 pm to 10 nanometers (corresponding to frequencies in the range 30 PHz... It has been suggested that Solid state physics be merged into this article or section. ... In nuclear and particle physics, the concept of a cross section is used to express the likelihood of interaction between particles. ...

The development of "neutron lenses" based on total internal reflection within hollow glass capillary tubes or by reflection from dimpled aluminum plates has driven ongoing research into neutron microscopy and neutron/gamma ray tomography.

One use of neutron emitters is the detection of light nuclei, particularly the hydrogen found in water molecules. When a fast neutron collides with a light nucleus, it loses a large fraction of its energy. By measuring the rate at which slow neutrons return to the probe after reflecting off of hydrogen nuclei, a neutron probe may determine the water content in soil. Impact of a drop of water. ... A neutron probe is a device used to measure the quantity of water present in soil. ...

## Sources

Main article: neutron source

Due to the fact that free neutrons are unstable, they (neutron radiation) can be obtained only from nuclear disintegrations, nuclear reactions, and high-energy reactions (such as in cosmic radiation showers or accelerator collisions). Free neutron beams are obtained from neutron sources by neutron transport. For access to intense neutron sources, researchers must go to specialist facilities, such as the ISIS facility in the UK, which is currently the world's most intense pulsed neutron and muon source. A neutron source is a device, used in solid state physics (see neutron diffraction), particle physics and to start nuclear chain reactions, that emits neutrons. ... Neutron radiation consists of free neutrons. ... A neutron source is a device, used in solid state physics (see neutron diffraction), particle physics and to start nuclear chain reactions, that emits neutrons. ... Beams of free neutrons are obtained by extracting neutrons from neutron sources. ... ISIS experimental hall The ISIS facility is a scientific research institution, situated at the Rutherford Appleton Laboratory in Oxfordshire, UK. It contains a pulsed spallation neutron source, the most powerful in the world, which enables muon and neutron scattering science to probe the structure and properties of matter, from the... The muon (from the letter mu (Î¼)--used to represent it) is an elementary particle with negative electric charge and a spin of 1/2. ...

Neutrons' lack of total electric charge prevents engineers or experimentalists from being able to steer or accelerate them. Charged particles can be accelerated, decelerated, or deflected by electric or magnetic fields. However, these methods have almost no effect on neutrons (there is a small effect of a magnetic field on the free neutron because of its magnetic moment). Lightning strikes during a night-time thunderstorm. ... Current (I) flowing through a wire produces a magnetic field () around the wire. ... A bar magnet. ...

## Current developments

The existence of stable clusters of four neutrons, or tetraneutrons, has been hypothesised by a team led by Francisco-Miguel Marqués at the CNRS Laboratory for Nuclear Physics based on observations of the disintegration of beryllium-14 nuclei. This is particularly interesting, because current theory suggests that such clusters should not be stable, and therefore should not exist. A tetraneutron is a hypothesised stable cluster of four neutrons. ... This article needs to be wikified. ... General Name, Symbol, Number beryllium, Be, 4 Chemical series alkaline earth metals Group, Period, Block 2, 2, s Appearance white-gray metallic Atomic mass 9. ...

An experiment at the Institut Laue-Langevin (ILL) has attempted to measure an electric dipole, or separation of charges, within the neutron, and is consistent with an electric dipole moment of zero. These results are important in developing theories that go beyond the Standard Model. See FRONTIERS article, and the experiment's web page. Institut Laue-Langevin The Institut Laue-Langevin is an internationally-financed scientific facility, situated in Grenoble, France. ... This article is about the electromagnetic phenomenon. ... The Standard Model of Fundamental Particles and Interactions For the Standard Model in Cryptography, see Standard Model (cryptography). ...

## Anti-Neutron

Main article: antineutron

The antineutron is the antiparticle of the neutron. It was discovered by Bruce Cork in the year 1956, a year after the antiproton was discovered. The antineutron is the antiparticle of the neutron. ... Corresponding to most kinds of particle, there is an associated antiparticle with the same mass and opposite charges. ... Physicist who discovered the antineutron in 1956. ... Year 1956 (MCMLVI) was a leap year starting on Sunday of the Gregorian calendar. ... The antiproton (aka pbar) is the antiparticle of the proton. ...

CPT-symmetry puts strong constraints on the relative properties of particles and antiparticles and, therefore, is open to stringent tests. The fractional difference in the masses of the neutron and antineutron is (9±5)×10−5. Since the difference is only about 2 standard deviations away from zero, this does not give any convincing evidence of CPT-violation.[1] CPT symmetry is a fundamental symmetry of physical laws under transformations that involve the inversions of charge, parity and time simultaneously. ... For each kind of particle, there is an associated antiparticle with the same mass but opposite electromagnetic, weak, and strong charges, as well as spin. ...

## Protection

### Fields concerning neutrons

Thousands of particles explode from the collision point of two relativistic (100 GeV per ion) gold ions in the STAR detector of the Relativistic Heavy Ion Collider. ... In physics, the quark model is a classification scheme for hadrons in terms of their valence quarks, ie, the quarks (and antiquarks) which give rise to the quantum numbers of the hadrons. ... Chemistry - the study of atoms, made of nuclei (center particles) and electrons (outer particles), and the structures they form. ... Neutron detection is the effective detection of neutrons entering a well-positioned laboratory detector. ... The term Neutron Scattering encompasses all scientific techniques whereby neutrons are used as a scientific probe. ...

### Types of neutrons

In physics a nucleon is a collective name for two baryons: the neutron and the proton. ... A fast neutron is a free neutron with a kinetic energy level close to 1 MeV (10 TJ/kg, hence a speed of 14,000 km/s. ... A free neutron is a neutron that exists outside of an atomic nucleus. ... This article does not cite its references or sources. ... Neutron radiation consists of free neutrons. ... The sievert (symbol: Sv) is the SI derived unit of dose equivalent. ... The neutron temperature indicates a free neutrons energy, usually given in electron volts. ...

### Objects containing neutrons

A dineutron is a particle consisting of two neutrons that is considered to have a transitory existence in nuclear reactions produced by helions that result in the formation of a proton and a nucleus having the same atomic number as the target nucleus but a mass number two units greater. ... A tetraneutron is a hypothesised stable cluster of four neutrons. ... Neutronium is a term used in science fiction and popular literature to refer to an extremely dense phase of matter composed primarily of neutrons. ... A neutron star is one of the few possible endpoints of stellar evolution. ...

### Neutron sources

A neutron source is a device, used in solid state physics (see neutron diffraction), particle physics and to start nuclear chain reactions, that emits neutrons. ... Neutron generators are devices which contain compact linear accelerators and that produce neutrons by fusing isotopes of hydrogen together. ...

### Processes involving neutrons

Beams of free neutrons are obtained by extracting neutrons from neutron sources. ... Neutron diffraction is a crystallography technique that uses neutrons to determine the atomic structure of a material. ... A neutron bomb is a type of tactical nuclear weapon developed specifically to release a relatively large portion of its energy as energetic neutron radiation. ...

 Particles in physics - composite particles v • d • e Hadrons: Baryons (list) | Mesons (list) Baryons: Nucleons | Hyperons | Exotic baryons | Pentaquarks Mesons: Pions | Kaons | Quarkonium | Exotic mesons Atomic nuclei | Atoms (Periodic table (vertical)) | Molecules Thousands of particles explode from the collision point of two relativistic (100 GeV per ion) gold ions in the STAR detector of the Relativistic Heavy Ion Collider. ... Elementary particles An elementary particle is a particle with no measurable internal structure, that is, it is not a composite of other particles. ... In particle physics, a hadron is a subatomic particle which experiences the strong nuclear force. ... In particle physics, the baryons are a family of subatomic particles including the proton and the neutron (collectively called nucleons), as well as a number of unstable, heavier particles (called hyperons). ... Baryon decuplet: Spin=3/2 Baryon octet: Spin=1/2 This is a list of baryons. ... Mesons of spin 1 form a nonet In particle physics, a meson is a strongly interacting boson, that is, it is a hadron with integral spin. ... A list of mesons. ... In physics a nucleon is a collective name for two baryons: the neutron and the proton. ... In particle physics, a hyperon is any subatomic particle which is a baryon (and hence a hadron and a fermion) with non-zero strangeness, but with zero charm and zero bottomness. ... Ordinary baryons are bound states of 3 quarks. ... A pentaquark is a subatomic particle consisting of a group of five quarks (compared to three quarks in normal baryons and two in mesons), or more specifically four quarks and one anti-quark. ... In particle physics, pion (short for pi meson) is the collective name for three subatomic particles: Ï€0, Ï€+ and Ï€âˆ’. Pions are the lightest mesons and play an important role in explaining low-energy properties of the strong nuclear force. ... In particle physics, Kaons (also called K-mesons and denoted K) are a group of four mesons distinguished by the fact that they carry a quantum number called strangeness. ... In high energy physics, a quarkonium (pl. ... Identities and classification of possible tetraquark mesons. ... A semi-accurate depiction of the helium atom. ... â€œAtomicâ€ redirects here. ... The alternative table is a standard periodic table rotated counterclockwise and then mirrored across the vertical axis, hence like in many writing systems, the lower groups are to the left and the number increases to the right. ... In science, a molecule is a group of atoms in a definite arrangement held together by chemical bonds. ...

## References

1. ^ a b c Particle Data Group's Review of Particle Physics 2006
2. ^ Povh, Rith, Scholz, Zetche, Particles and Nuclei, 1999, ISBN 3-540-43823-8

Results from FactBites:

 Neutron - Wikipedia, the free encyclopedia (1262 words) Although the neutron has zero net charge, it may interact electromagnetically in two ways: first, the neutron has a magnetic moment of the same order as the proton; second, it is composed of electrically charged quarks. Neutrons that elastically scatter off atoms can create an ionization track that is detectable, but the experiments are not as simple to carry out; other means for detecting neutrons, consisting of allowing them to interact with atomic nuclei, are more commonly used. One use of neutron emitters is the detection of light nuclei, particularly the hydrogen found in water molecules.
 Neutron - MSN Encarta (1492 words) Neutron, electrically neutral elementary particle that is part of the nucleus of the atom. The neutron is also affected by the weak nuclear force, an interaction among the building blocks of the neutron that causes the neutron to decay, or break apart. The neutrons are responsible for the remaining mass of the atom.
More results at FactBites »

Share your thoughts, questions and commentary here