query: how can a proton turn into a neutron

pos: Beta decay atoms obtain a more stable ratio of protons to neutrons. The probability of a nuclide decaying due to beta and other forms of decay is determined by its nuclear binding energy. The binding energies of all existing nuclides form what is called the nuclear band or valley of stability. For either electron or positron emission to be energetically possible, the energy release (see below) or Q value must be positive. Beta decay is a consequence of the weak force, which is characterized by relatively lengthy decay times. Nucleons are composed of up quarks and down quarks, and the weak force

pos: Beta decay a few cases of odd-proton, odd-neutron radionuclides, it may be energetically favorable for the radionuclide to decay to an even-proton, even-neutron isobar either by undergoing beta-positive or beta-negative decay. An often-cited example is the single isotope (29 protons, 35 neutrons), which illustrates three types of beta decay in competition. Copper-64 has a half-life of about 12.7 hours. This isotope has one unpaired proton and one unpaired neutron, so either the proton or the neutron can decay. This particular nuclide (though not all nuclides in this situation) is almost equally likely to decay through proton decay by positron emission (18%) or

pos: Neutron contain an excess of neutrons is also possible, but is hindered because positrons are repelled by the positive nucleus, and quickly annihilate when they encounter electrons. Three types of beta decay in competition are illustrated by the single isotope copper-64 (29 protons, 35 neutrons), which has a half-life of about 12.7 hours. This isotope has one unpaired proton and one unpaired neutron, so either the proton or the neutron can decay. This particular nuclide is almost equally likely to undergo proton decay (by positron emission, 18% or by electron capture, 43%) or neutron decay (by electron emission, 39%). The mass

pos: Beta decay in the nucleus, transforming it into a neutron, and an electron neutrino is released. The two types of beta decay are known as "beta minus" and "beta plus". In beta minus (β) decay, a neutron is converted to a proton, and the process creates an electron and an electron antineutrino; while in beta plus (β) decay, a proton is converted to a neutron and the process creates a positron and an electron neutrino. β decay is also known as positron emission. Beta decay conserves a quantum number known as the lepton number, or the number of electrons and their associated

pos: Decay chain to achieve stability, most usually as alpha decay. The other common decay method for isotopes with a high neutron to proton ratio (n/p) is beta decay, in which the nuclide changes elemental identity while keeping the same weight and lowering its n/p ratio. For some isotopes with a relatively low n/p ratio, there is an inverse beta decay, by which a proton is transformed into a neutron, thus moving towards a stable isotope; however, since fission almost always produces products which are neutron heavy, positron emission is relatively rare compared to electron emission. There are many relatively short beta decay

pos: Beta decay Beta decay In nuclear physics, beta decay ("β"-decay) is a type of radioactive decay in which a beta ray (fast energetic electron or positron) and a neutrino are emitted from an atomic nucleus. For example, beta decay of a neutron transforms it into a proton by the emission of an electron, or conversely a proton is converted into a neutron by the emission of a positron (positron emission), thus changing the nuclide type. Neither the beta particle nor its associated neutrino exist within the nucleus prior to beta decay, but are created in the decay process. By this process, unstable

pos: Positron emission Positron emission Positron emission or beta plus decay (β decay) is a subtype of radioactive decay called beta decay, in which a proton inside a radionuclide nucleus is converted into a neutron while releasing a positron and an electron neutrino ("ν"). Positron emission is mediated by the weak force. The positron is a type of beta particle (β), the other beta particle being the electron (β) emitted from the β decay of a nucleus. An example of positron emission (β decay) is shown with magnesium-23 decaying into sodium-23: Because positron emission decreases proton number relative to neutron number, positron decay

neg: Nucleon protons and neutrons (nucleons) can be stable or unstable depending on the nuclide, or nuclear species. Inside some nuclides, a neutron can turn into a proton (producing other particles) as described above; the reverse can happen inside other nuclides, where a proton turns into a neutron (producing other particles) through decay, or electron capture. And inside still other nuclides, both protons and neutrons are stable and do not change form. Both nucleons have corresponding antiparticles: the antiproton and the antineutron, which have the same mass and opposite charge as the proton and neutron respectively, and they interact in the same

neg: Ionizing radiation minutes, 42 seconds. Free neutrons decay by emission of an electron and an electron antineutrino to become a proton, a process known as beta decay: In the adjacent diagram, a neutron collides with a proton of the target material, and then becomes a fast recoil proton that ionizes in turn. At the end of its path, the neutron is captured by a nucleus in an (n,γ)-reaction that leads to the emission of a neutron capture photon. Such photons always have enough energy to qualify as ionizing radiation. Neutron radiation, alpha radiation, and extremely energetic gamma (> ~20 MeV) can cause

neg: Magnetic proton recoil neutron spectrometer plasma parameters can be determined, such as the ion temperature, the collective motion of the main plasma, the fuel ion densities and their velocity distributions. The thin-foil magnetic proton recoil neutron spectrometer MPRu at JET Magnetic proton recoil neutron spectrometer Magnetic Proton Recoil neutron spectrometer is a large high-resolution neutron spectrometer installed at JET. The Magnetic Proton Recoil (MPR) neutron spectrometer is a thin-foil spectrometer which was installed at JET in 1996 and upgraded (MPRu) 2001-2005. In the MPR the fusion neutrons are collimated into a neutron beam. The neutron beam is directed onto a thin plastic film (Polyethylene) where

neg: Neutron proton to a neutron (plus a positron and a neutrino) is energetically impossible, since a free neutron has a greater mass than a free proton. But a high-energy collision of a proton and an electron or neutrino can result in a neutron. While a free neutron has a half life of about 10.2 min, most neutrons within nuclei are stable. According to the nuclear shell model, the protons and neutrons of a nuclide are a quantum mechanical system organized into discrete energy levels with unique quantum numbers. For a neutron to decay, the resulting proton requires an available state at

neg: Beta decay a neutron However, decay cannot occur in an isolated proton because it requires energy due to the mass of the neutron being greater than the mass of the proton. decay can only happen inside nuclei when the daughter nucleus has a greater binding energy (and therefore a lower total energy) than the mother nucleus. The difference between these energies goes into the reaction of converting a proton into a neutron, a positron and a neutrino and into the kinetic energy of these particles. This process is opposite to negative beta decay, in that the weak interaction converts a proton into

neg: Neutron allowed quantum state is available for the proton resulting from the decay. One example of this decay is carbon-14 (6 protons, 8 neutrons) that decays to nitrogen-14 (7 protons, 7 neutrons) with a half-life of about 5,730 years. Inside a nucleus, a proton can transform into a neutron via inverse beta decay, if an energetically allowed quantum state is available for the neutron. This transformation occurs by emission of a positron and an electron neutrino: The transformation of a proton to a neutron inside of a nucleus is also possible through electron capture: Positron capture by neutrons in nuclei that

neg: Oppenheimer–Phillips process energy. In such instances, the transmuted nucleus is left in an energy state as if it had fused with a neutron of negative kinetic energy. There is an upper bound of how much energy the proton can be ejected with, set by the ground state of the daughter nucleus. Oppenheimer–Phillips process The Oppenheimer–Phillips process or strip reaction is a type of deuteron-induced nuclear reaction. In this process the neutron half of an energetic deuteron (a stable isotope of hydrogen with one proton and one neutron) fuses with a target nucleus, transmuting the target to a heavier isotope while ejecting a

neg: Quark and top quarks) can change into any down-type quark (down, strange, and bottom quarks) and vice versa. This flavor transformation mechanism causes the radioactive process of beta decay, in which a neutron () "splits" into a proton (), an electron () and an electron antineutrino () (see picture). This occurs when one of the down quarks in the neutron () decays into an up quark by emitting a virtual boson, transforming the neutron into a proton (). The boson then decays into an electron and an electron antineutrino. Both beta decay and the inverse process of "inverse beta decay" are

neg: Magnetic proton recoil neutron spectrometer Magnetic proton recoil neutron spectrometer Magnetic Proton Recoil neutron spectrometer is a large high-resolution neutron spectrometer installed at JET. The Magnetic Proton Recoil (MPR) neutron spectrometer is a thin-foil spectrometer which was installed at JET in 1996 and upgraded (MPRu) 2001-2005. In the MPR the fusion neutrons are collimated into a neutron beam. The neutron beam is directed onto a thin plastic film (Polyethylene) where the neutrons scatter elastically on the protons of the foil. The recoil protons emitted in the forward direction enter a magnetic part of the spectrometer where they are momentum analyzed and focused onto the focal

neg: Valley of stability on the neutron-rich side, and the proton drip line on the proton-rich side. The nucleon drip lines are at the extremes of the neutron-proton ratio. At neutron–proton ratios beyond the drip lines, no nuclei can exist. The location of the neutron drip line is not well known for most of the Segrè chart, whereas the proton and alpha drip lines have been measured for a wide range of elements. Drip lines are defined for protons, neutrons, and alpha particles, and these all play important roles in nuclear physics. The difference in binding energy between neighboring nuclides increases as the sides

neg: Nuclear drip line nuclei that are longer lived and undergo proton or neutron emission are in the class of beta-delayed decays, where first the isospin of one nucleon is reversed (proton to neutron or vice versa) via beta decay, and then if the particle separation energy is non-positive, the daughter nucleus will undergo particle decay. Most naturally occurring γ-sources are technically β-delayed γ-decay, so this concept should be familiar; some gamma-sources are α-delayed but these are generally categorized with other alpha-sources. We can see how the drip lines originate by considering the energy levels in a nucleus. The energy of a nucleon in

neg: Nucleon models, such as the nuclear shell model. These models can successfully explain nuclide properties, as for example, whether or not a particular nuclide undergoes radioactive decay. The proton and neutron are both baryons and both fermions. The proton carries a positive net charge and the neutron carries a zero net charge; the proton's mass is only about 0.13% less than the neutron's. Thus, they can be viewed as two states of the same nucleon, and together form an isospin doublet (). In isospin space, neutrons can be transformed into protons via SU(2) symmetries, and vice versa. These nucleons are acted

neg: Proton–proton chain reaction the Coulomb barrier. After the development of quantum mechanics, it was discovered that tunneling of the wavefunctions of the protons through the repulsive barrier allows for fusion at a lower temperature than the classical prediction. Even so, it was unclear how proton–proton fusion might proceed, because the most obvious product, helium-2 (diproton), is unstable and almost instantly dissociates back into two protons. In 1939, Hans Bethe proposed that one of the protons could decay by beta emission into a neutron via the weak interaction during the brief moment of fusion, making deuterium a vital product in the chain. This idea

neg: Neutron radiation Neutron radiation Neutron radiation is a form of ionizing radiation that presents as free neutrons. Typical phenomena are nuclear fission or nuclear fusion causing the release of free neutrons, which then react with nuclei of other atoms to form new isotopes—which, in turn, may trigger further neutron radiation. Free neutrons are unstable, decaying into a proton, an electron, plus an anti-electron-neutrino with a mean lifetime of 887 seconds (about 14 minutes, 47 seconds). Neutrons may be emitted from nuclear fusion or nuclear fission, or from other nuclear reactions such as radioactive decay or particle interactions with cosmic rays or within

neg: Discovery of the neutron that of the proton. Rutherford determined that such a zero-charge particle would be difficult to detect by available techniques. By 1921 Rutherford had named the uncharged particle the "neutron", while about that same time the word "proton" was adopted for the hydrogen nucleus. Neutron was apparently constructed from the Latin root for "neutral" and the Greek ending "-on" (by imitation of "electron" and "proton"). References to the word "neutron" in connection with the atom can be found in the literature as early as 1899, however. Rutherford and Chadwick immediately began an experimental program to search for the neutron at the

neg: Neutron of a neutron cannot be directly determined by mass spectrometry due to lack of electric charge. However, since the masses of a proton and of a deuteron can be measured with a mass spectrometer, the mass of a neutron can be deduced by subtracting proton mass from deuteron mass, with the difference being the mass of the neutron plus the binding energy of deuterium (expressed as a positive emitted energy). The latter can be directly measured by measuring the energy (formula_1) of the single gamma photon emitted when neutrons are captured by protons (this is exothermic and happens with zero-energy

neg: Beta particle particles, but more ionising than gamma rays. The higher the ionising effect, the greater the damage to living tissue. An unstable atomic nucleus with an excess of neutrons may undergo β decay, where a neutron is converted into a proton, an electron, and an electron antineutrino (the antiparticle of the neutrino): This process is mediated by the weak interaction. The neutron turns into a proton through the emission of a virtual W boson. At the quark level, W emission turns a down quark into an up quark, turning a neutron (one up quark and two down quarks) into a proton

neg: Nuclide into a nucleus. As the number of protons increases, so does the ratio of neutrons to protons necessary to ensure a stable nucleus (see graph at right). For example, although the [[proton–neutron ratio|neutron–proton ratio]] of is 1:2, the neutron–proton ratio of is greater than 3:2. A number of lighter elements have stable nuclides with the ratio 1:1 (). The nuclide (calcium-40) is observationally the heaviest stable nuclide with the same number of neutrons and protons; (theoretically, the heaviest stable one is sulfur-32). All stable nuclides heavier than calcium-40 contain more neutrons than protons. The proton–neutron ratio is not the only

neg: Nuclide are even-proton–even-neutron, where all numbers "Z", "N", and "A" are even. The odd-"A" stable nuclides are divided (roughly evenly) into odd-proton–even-neutron, and even-proton–odd-neutron nuclides. Odd-proton–odd-neutron nuclides (and nuclei) are the least common. [[Category:Isotopes]] [[Category:Nuclear physics]] Nuclide A nuclide (or nucleide, from nucleus, also known as nuclear species) is an atomic species characterized by the specific constitution of its nucleus, i.e., by its number of protons "Z", its number of neutrons "N", and its nuclear energy state. The word "nuclide" was proposed by Truman P. Kohman in 1947. Kohman originally suggested "nuclide" as referring to a "species of atom characterized by

neg: Geoneutrino with a proton, producing a positron and a neutron: Only antineutrinos with energies above the kinematic threshold of 1.804 MeV—the difference between rest mass energies of neutron plus positron and proton—can participate in this interaction. After depositing its kinetic energy, the positron promptly annihilates with an electron: With a delay of few tens to few hundred microseconds the neutron combines with a proton to form a deuteron: The two light flashes associated with the positron and the neutron are coincident in time and in space, which provides a powerful method to reject single-flash (non-antineutrino) background events in the liquid scintillator.

neg: Isotope The odd-"A" stable nuclides are divided (roughly evenly) into odd-proton-even-neutron, and even-proton-odd-neutron nuclides. Odd-proton-odd-neutron nuclei are the least common. The 148 even-proton, even-neutron (EE) nuclides comprise ~ 58% of all stable nuclides and all have spin 0 because of pairing. There are also 22 primordial long-lived even-even nuclides. As a result, each of the 41 even-numbered elements from 2 to 82 has at least one stable isotope, and most of these elements have "several" primordial isotopes. Half of these even-numbered elements have six or more stable isotopes. The extreme stability of helium-4 due to a double pairing of 2 protons

neg: Force virtual particle exchange, are absorbed at an adjacent vertex. The utility of Feynman diagrams is that other types of physical phenomena that are part of the general picture of fundamental interactions but are conceptually separate from forces can also be described using the same rules. For example, a Feynman diagram can describe in succinct detail how a neutron decays into an electron, proton, and neutrino, an interaction mediated by the same gauge boson that is responsible for the weak nuclear force. All of the known forces of the universe are classified into four fundamental interactions. The strong and the weak

neg: Neutron moderator (a proton) could result in the neutron losing virtually all of its energy in a single head-on collision. More generally, it is necessary to take into account both glancing and head-on collisions. The "mean logarithmic reduction of neutron energy per collision", formula_7, depends only on the atomic mass, formula_8, of the nucleus and is given by: formula_9. This can be reasonably approximated to the very simple form formula_10. From this one can deduce formula_11, the expected number of collisions of the neutron with nuclei of a given type that is required to reduce the kinetic energy of a neutron from

neg: Isotopes of hydrogen one tritium nucleus captures two neutrons from the other, becoming a nucleus with one proton and four neutrons. The remaining proton may be detected, and the existence of hydrogen-5 deduced. It decays through double neutron emission into hydrogen-3 (tritium) and has a half-life of at least 910 yoctoseconds (9.1 × 10 seconds). H decays either through triple neutron emission into hydrogen-3 (tritium) or quadruple neutron emission into hydrogen-2 (deuterium) and has a half-life of 290 yoctoseconds (2.9 × 10 seconds). H consists of a proton and six neutrons. It was first synthesised in 2003 by a group of Russian, Japanese

neg: Nucleon 0, respectively. Thus, the neutron has a charge of 0 (zero), and therefore is electrically neutral; indeed, the term "neutron" comes from the fact that a neutron is electrically neutral. The mass of the proton and neutron is quite similar: The proton is or , while the neutron is or . The neutron is roughly 0.13% heavier. The similarity in mass can be explained roughly by the slight difference in masses of up quarks and down quarks composing the nucleons. However, a detailed explanation remains an unsolved problem in particle physics. The spin of both protons and neutrons is ,

neg: Beta decay emit a positron and neutrino. If the proton and neutron are part of an atomic nucleus, the above described decay processes transmute one chemical element into another. For example: Beta decay does not change the number () of nucleons in the nucleus, but changes only its charge . Thus the set of all nuclides with the same can be introduced; these "isobaric" nuclides may turn into each other via beta decay. For a given there is one that is most stable. It is said to be beta stable, because it presents a local minima of the mass excess: if such

neg: Nucleon magnetic moment of a neutron is μ = . These parameters are also important in NMR/MRI. A neutron in free state is an unstable particle, with a half-life around ten minutes. It undergoes decay (a type of radioactive decay) by turning into a proton while emitting an electron and an electron antineutrino. (See the Neutron article for more discussion of neutron decay.) A proton by itself is thought to be stable, or at least its lifetime is too long to measure. This is an important discussion in particle physics, (see Proton decay). Inside a nucleus, on the other hand, combined

neg: Radiochemistry some form of radiation. The radiation emitted can be of several types including alpha, beta, gamma radiation, proton and neutron emission along with neutrino and antiparticle emission decay pathways. 1. α (alpha) radiation—the emission of an alpha particle (which contains 2 protons and 2 neutrons) from an atomic nucleus. When this occurs, the atom's atomic mass will decrease by 4 units and atomic number will decrease by 2. 2. β (beta) radiation—the transmutation of a neutron into an electron and a proton. After this happens, the electron is emitted from the nucleus into the electron cloud. 3. γ (gamma) radiation—the

neg: Photodisintegration carrying 2.22 MeV or more energy can photodisintegrate an atom of deuterium: James Chadwick and Maurice Goldhaber used this reaction to measure the proton-neutron mass difference. This experiment proves that a neutron is not a bound state of a proton and an electron, as had been proposed by Ernest Rutherford. A photon carrying 1.67 MeV or more energy can photodisintegrate an atom of beryllium-9 (100% of natural beryllium, its only stable isotope): Antimony-124 is assembled with beryllium to make laboratory neutron sources and startup neutron sources. Antimony-124 (half-life 60.20 days) emits β− and 1.690MeV gamma rays (also 0.602MeV and 9

neg: Deuterium is often negligible due to the weakness of the electromagnetic interaction relative to the strong nuclear interaction. The symmetry relating the proton and neutron is known as isospin and denoted "I" (or sometimes "T"). Isospin is an SU(2) symmetry, like ordinary spin, so is completely analogous to it. The proton and neutron form an isospin doublet, with a "down" state (↓) being a neutron, and an "up" state (↑) being a proton. A pair of nucleons can either be in an antisymmetric state of isospin called singlet, or in a symmetric state called triplet. In terms of the "down" state

neg: P-nuclei P-nuclei p-nuclei ("p" stands for proton-rich) are certain proton-rich, naturally occurring isotopes of some elements between selenium and mercury inclusive which cannot be produced in either the s- or the r-process. The classical, ground-breaking works of Burbidge, Burbidge, Fowler and Hoyle (1957) and of A. G. W. Cameron (1957) showed how the majority of naturally occurring nuclides beyond the element iron can be made in two kinds of neutron capture processes, the s- and the r-process. Some proton-rich nuclides found in nature are not reached in these processes and therefore at least one additional process is required to synthesize them.

neg: Discovery of the neutron model became viable. Soon, neutrons were used to naturally explain spin differences in many different nuclides in the same way. If the proton–neutron model for the nucleus resolved many issues, it highlighted the problem of explaining the origins of beta radiation. No existing theory could account for how electrons, or positrons, could emanate from the nucleus. In 1934, Enrico Fermi published his classic paper describing the process of beta decay, in which the neutron decays to a proton by "creating" an electron and a (as yet undiscovered) neutrino. The paper employed the analogy that photons, or electromagnetic radiation, were similarly

neg: Discovery of the neutron Heisenberg had no explanation for how lightweight electrons could be bound within the nucleus. Heisenberg introduced the first theory of nuclear exchange forces that bind the nucleons. He considered protons and neutrons to be different quantum states of the same particle, i.e., nucleons distinguished by the value of their nuclear isospin quantum numbers. The proton–neutron model explained the puzzle of dinitrogen. When N was proposed to consist of 3 pairs each of protons and neutrons, with an additional unpaired neutron and proton each contributing a spin of ħ in the same direction for a total spin of 1 ħ, the

neg: Spin magnetic moment The proton and neutron are composed of quarks, which have a non-zero charge and a spin of "ħ"/2, and this must be taken into account when calculating their g-factors. Even though the neutron has a charge , its quarks give it a magnetic moment. The proton and electron's spin magnetic moments can be calculated by setting and , respectively, where "e" is the elementary charge. The intrinsic electron magnetic dipole moment is approximately equal to the Bohr magneton "μ" because and the electron's spin is also "ħ"/2: Equation () is therefore normally written as Just like the "total spin angular

neg: Particle accelerator National Laboratory. Particle accelerators can also produce proton beams, which can produce proton-rich medical or research isotopes as opposed to the neutron-rich ones made in fission reactors; however, recent work has shown how to make Mo, usually made in reactors, by accelerating isotopes of hydrogen, although this method still requires a reactor to produce tritium. An example of this type of machine is LANSCE at Los Alamos. Besides being of fundamental interest, electrons accelerated in the magnetic field causes the high energy electrons to emit extremely bright and coherent beams of high energy photons via synchrotron radiation in the continuous

neg: Fermi's interaction usual formula_22 spin matrix). The operators that change a heavy particle from a proton into a neutron and vice versa are respectively represented by and formula_25 resp. formula_26 is an eigenfunction for a neutron resp. proton in the state formula_27. The Hamiltonian is composed of three parts: formula_28, representing the energy of the free heavy particles, formula_29, representing the energy of the free light particles, and a part giving the interaction formula_30. where formula_32 and formula_33 are the energy operators of the neutron and proton respectively, so that if formula_34, formula_35, and if formula_36, formula_37. where formula_39 is the energy

neg: Neutron–proton ratio which it is fissioned. For stable nuclei, the neutron-proton ratio is such that the bonding energy is at a local minimum or close to a minimum. From the liquid drop model, this bonding energy is approximated by empirical Bethe–Weizsäcker formula Given a value of formula_2 and ignoring the contributions of nucleon spin pairing (i.e. ignoring the formula_3 term), the binding energy is a quadratic expression in formula_4 that is minimized when the neutron-proton ratio is formula_5. Neutron–proton ratio The neutron–proton ratio (N/P ratio or nuclear ratio) of an atomic nucleus is the ratio of its number of neutrons to its

neg: Radioactive decay emitting nucleons, but highly excited nuclei can eject single nucleons, or in the case of cluster decay, specific light nuclei of other elements. Beta decay occurs in two ways: (i) beta-minus decay, when the nucleus emits an electron and an antineutrino in a process that changes a neutron to a proton, or (ii) beta-plus decay, when the nucleus emits a positron and a neutrino in a process that changes a proton to a neutron. Highly excited neutron-rich nuclei, formed as the product of other types of decay, occasionally lose energy by way of neutron emission, resulting in a change from

neg: Weak interaction picture, above), a down quark within the neutron emits a virtual boson and is thereby converted into an up quark, converting the neutron into a proton. Because of the energy involved in the process (i.e., the mass difference between the down quark and the up quark), the boson can only be converted into an electron and an electron-antineutrino. At the quark level, the process can be represented as: In neutral current interactions, a quark or a lepton (e.g., an electron or a muon) emits or absorbs a neutral Z boson. For example: Like the W boson, the Z boson also

neg: Neutron end of World War II. Under the Standard Model of particle physics, the only possible decay mode for the neutron that conserves baryon number is for one of the neutron's quarks to change flavour via the weak interaction. The decay of one of the neutron's down quarks into a lighter up quark can be achieved by the emission of a W boson. By this process, the Standard Model description of beta decay, the neutron decays into a proton (which contains one down and two up quarks), an electron, and an electron antineutrino. Since interacting protons have a mutual electromagnetic repulsion

neg: Isospin heavier quarks must be treated separately. Hadron nomenclature is based on isospin. Isospin was introduced as a concept in 1932, well before the 1960s development of the quark model. The man who introduced it, Werner Heisenberg, did so to explain symmetries of the then newly discovered neutron (symbol n): This behavior is not unlike the electron, where there are two possible states based on their spin. Other properties of the particle are conserved in this case. Heisenberg introduced the concept of another conserved quantity that would cause the proton to turn into a neutron and vice versa. In 1937, Eugene

neg: Nuclear drip line especially useful as limiting boundaries for explosive nucleosynthesis as well as other circumstances with extreme pressure or temperature conditions such as neutron stars. Explosive astrophysical environments often have very large fluxes of high energy nucleons that can be captured on seed nuclei. In these environments, radiative proton or neutron capture will occur much faster than beta decays, and as astrophysical environments with both large neutron fluxes and high energy protons are unknown at present, the reaction flow will proceed away from beta-stability towards or up to either the neutron or proton drip lines, respectively. However, once a nucleus reaches a

neg: Discovery of the neutron a free neutron would be able to decay into a proton, electron, and neutrino (beta decay). Soon after the discovery of the neutron, indirect evidence suggested the neutron had an unexpected non-zero value for its magnetic moment. Attempts to measure the neutron's magnetic moment originated with the discovery by Otto Stern in 1933 in Hamburg that the proton had an anomalously large magnetic moment. By 1934 groups led by Stern, now in Pittsburgh, and I. I. Rabi in New York had independently deduced that the magnetic moment of the neutron was negative and unexpectedly large by measuring the magnetic moments

neg: Proton magnetic moment deuteron has the simplest example of a nuclear magnetic moment, with measured value 0.857 "µ". This value is within 3% of the sum of the moments of the proton and neutron, which gives 0.879 "µ". In this calculation, the spins of the nucleons are aligned, but their magnetic moments offset because of the neutron's negative magnetic moment. Within the quark model for hadrons, such as the neutron, the proton is composed of one down quark (charge -1/3 "e") and two up quarks (charge +2/3 "e"). The magnetic moment of the proton can be modeled as a sum of the magnetic

neg: Nuclear magnetic moment "pure" states, though it may be close to one or the other (as in deuterium). The values of "g" and "g" are known as the "g"-factors of the nucleons. The measured values of g for the neutron and the proton are according to their electric charge. Thus, in units of nuclear magneton, for the neutron and for the proton. The measured values of "g" for the neutron and the proton are twice their magnetic moment (either the neutron magnetic moment or the proton magnetic moment). In nuclear magneton units, for the neutron and for the proton. The gyromagnetic ratio, expressed

neg: James Chadwick was best described as a new nuclear particle, but its exact nature remained unclear. In his 1933 Bakerian Lecture, Chadwick estimated that a neutron had a mass of about . Since a proton and an electron had a combined mass of , this implied the neutron as a proton–electron composite had a binding energy of about , which sounded reasonable, although it was hard to understand how a particle with so little binding energy could be stable. Estimating such a small mass difference required challenging precise measurements, however, and several conflicting results were obtained in 1933–4. By bombarding boron with

neg: Delta baryon neutron) and a pion of appropriate charge. The relative probabilities of allowed final charge states are given by their respective isospin couplings. More rarely and more slowly, the can decay into a proton and a photon and the can decay into a neutron and a photon. PDG reports the resonance width (Γ). Here the conversion formula_1 is given instead. Delta baryon The Delta baryons (or Δ baryons, also called Delta resonances) are a family of subatomic particle made of three up or down quarks (u or d quarks). Four closely related Δ baryons exist: (constituent quarks: uuu), (uud), (udd), and

neg: Magnetic proton recoil neutron spectrometer plane. An array of plastic scintillators coupled to photomultiplier tubes (PMTs) register the spatial distribution of the protons. This proton distribution is then related to the neutron energy spectrum. The MPR has a semi-tangential line of sight through the plasma. The MPR has a 700 mm long cylindrical steel neutron collimator with a 10-cm2 bore. At a distance 170 mm behind the end of the collimator is placed a 10 cm2 polythene conversion foil, defining the active area of the spectrometer. The collimator-foil arrangement defines the spectrometers field-of-view into the plasma. The MPR determines the neutron spectrum from which important

neg: Oppenheimer–Phillips process preferentially at one end of the deuteron's density distribution, nominally, the "proton end". As the deuteron approaches the target nucleus, the positive charge is repelled by the electrostatic field until, assuming the incident energy is not sufficient for it to surmount the barrier, the "proton end" approaches to a minimum distance having climbed the Coulomb barrier as far as it can. If the "neutron end" is close enough for the strong nuclear force, which only operates over very short distances, to exceed the repulsive electrostatic force on the "proton end", fusion of a neutron with the target nucleus may begin.

neg: Mass nucleus of deuterium, to the mass of the proton in free space (which is greater by about 0.239% - this is due to the binding energy of deuterium.). Thus, for example, if the reference weight "m" is taken to be the mass of the neutron in free space, and the relative accelerations for the proton and neutron in deuterium are computed, then the above formula over-estimates the mass "m" (by 0.239%) for the proton in deuterium. At best, Mach's formula can only be used to obtain ratios of masses, that is, as "m" /"m" = |a| / |a|. An additional

neg: Deuterium the particles in the steep gradient of the nuclear force. In both cases, this causes the diproton and dineutron nucleus to be unstable. The proton and neutron making up deuterium can be dissociated through neutral current interactions with neutrinos. The cross section for this interaction is comparatively large, and deuterium was successfully used as a neutrino target in the Sudbury Neutrino Observatory experiment. Due to the similarity in mass and nuclear properties between the proton and neutron, they are sometimes considered as two symmetric types of the same object, a nucleon. While only the proton has an electric charge, this

neg: Neutron described above, can be denoted by the radioactive decay: where , , and denote the proton, electron and electron antineutrino, respectively. For the free neutron the decay energy for this process (based on the masses of the neutron, proton, and electron) is 0.782343 MeV. The maximal energy of the beta decay electron (in the process wherein the neutrino receives a vanishingly small amount of kinetic energy) has been measured at 0.782 ± 0.013 MeV. The latter number is not well-enough measured to determine the comparatively tiny rest mass of the neutrino (which must in theory be subtracted from the maximal

neg: Eightfold way (physics) interactions are looked at, but they are not truly exact symmetries of the universe because the three quarks have different masses and different electroweak interactions. This approximate symmetry is called "flavour symmetry", or more specifically "flavour SU(3) symmetry". Assume we have a certain particle—for example, a proton—in a quantum state formula_4. If we apply one of the flavour rotations "A" to our particle, it enters a new quantum state which we can call formula_5. Depending on "A", this new state might be a proton, or a neutron, or a superposition of a proton and a neutron, or various other possibilities.

neg: Proton the decay of a proton from oxygen-16. This experiment was designed to detect decay to any product, and established a lower limit to a proton lifetime of . However, protons are known to transform into neutrons through the process of electron capture (also called inverse beta decay). For free protons, this process does not occur spontaneously but only when energy is supplied. The equation is: The process is reversible; neutrons can convert back to protons through beta decay, a common form of radioactive decay. In fact, a free neutron decays this way, with a mean lifetime of about 15 minutes.

neg: Discovery of the neutron topic of discussion at the 7th Solvay Conference held in October 1933, attended by Heisenberg, Niels Bohr, Lise Meitner, Ernest Lawrence, Fermi, Chadwick, and others. As posed by Chadwick in his Bakerian Lecture in 1933, the primary question was the mass of the neutron relative to the proton. If the neutron's mass was less than the combined masses of a proton and an electron (), then the neutron could be a proton-electron composite because of the mass defect from the binding energy. If greater than the combined masses, then the neutron was elementary like the proton. The question was challenging

neg: Accelerator Neutrino Neutron Interaction Experiment is expected to be lower for "CC" interactions. This can be used to distinguish electron neutrino oscillation candidates from backgrounds such as neutral pion or photon production. Additionally, ANNIE will look for appearance of electron neutrinos in the beam-line. Proton decay is a prediction of many grand unification theories. ANNIE will characterize the neutron yield of events that generate signatures similar to those of proton decay in water Cherenkov detectors. The two channels of proton decay that are of interest to ANNIE, and most popular among GUTs are: The former is the preferred decay channel in minimal SU(5) and SO(10)

neg: Fermilab E-906/SeaQuest Fermilab E-906/SeaQuest Fermilab E-906/SeaQuest is a particle physics experiment which will use Drell–Yan process to measure the contributions of antiquarks to the structure of the proton or neutron and how this structure is modified when the proton or neutron is included within an atomic nucleus. The Fermilab E-906/SeaQuest experiment is part of a series of fixed target Drell–Yan experiments designed to measure the quark and antiquark structure of the nucleon and the modifications to that structure. With these measurements, SeaQuest will also be able to quantify the energy loss of a colored parton (quark) travelling through cold, strongly-interacting matter. SeaQuest

neg: Free neutron decay proton; the then decays into the electron and the antineutrino. The following equations denote the same process as the first equation above, but also include the short-lived and describe the process on both the nucleon and the quark level: For the free neutron, the decay energy for this process (based on the rest masses of the neutron, proton and electron) is 0.782343 MeV. That is the difference between the rest mass of the neutron and the sum of the rest masses of the products. That difference has to be carried away as kinetic energy. The maximal energy of the beta

neg: Discovery of the neutron simple mass balance where m refer to the deuteron, proton, or neutron mass, and "b.e." is the binding energy. The masses of the deuteron and proton were known; Chadwick and Goldhaber used values 2.0142 u and 1.0081 u, respectively. They found that the neutron's mass was slightly greater than the mass of the proton or , depending on the precise value used for the deuteron mass. The mass of the neutron was too large to be a proton-electron composite, and the neutron was therefore identified as an elementary particle. Ironically, in support of Fermi's theory, Chadwick and Goldhaber predicted that

neg: ISIS neutron source kW proton beam. The impacts cause neutrons to spall off the tungsten atoms, and the neutrons are channelled through guides, or beamlines, to around 20 instruments, each individually optimised for the study of different types of interactions between the neutron beam and matter. The target station and most of the instruments are set in a large hall. Neutrons are a dangerous form of radiation, so the target and beamlines are heavily shielded with concrete. ISIS Neutron and Muon Source produces muons by colliding a fraction of the proton beam with a graphite target, producing pions which decay rapidly into muons,

neg: Electron neutrino not larger than 0.01 proton mass. The continuous "β"-spectrum would then become understandable by the assumption that in "β" decay a neutron is emitted together with the electron, in such a way that the sum of the energies of neutron and electron is constant. But I don't feel secure enough to publish anything about this idea, so I first turn confidently to you, dear radioactives, with a question as to the situation concerning experimental proof of such a neutron, if it has something like about 10 times the penetrating capacity of a "γ" ray. I admit that my remedy may

neg: Nuclear pasta compression causes the spaghetti phase rods to fuse and form sheets of nuclear matter called the lasagna phase. Further compression of the lasagna phase yields the uniform nuclear matter of the outer core with intermittent holes of neutron (and possibly proton) liquid. Progressing deeper into the inner crust, those holes in the nuclear pasta change from being cylindrical, called by some the bucatini phase or antispaghetti phase, into scattered spherical holes, which can be called the Swiss cheese phase. The nuclei disappear at the crust–core interface, transitioning into the liquid core of the star. For a typical neutron star of

neg: Neutron ordinarily non-fissile materials, such as depleted uranium (uranium-238), and these materials have been used in the jackets of thermonuclear weapons. Fusion neutrons also can cause fission in substances that are unsuitable or difficult to make into primary fission bombs, such as reactor grade plutonium. This physical fact thus causes ordinary non-weapons grade materials to become of concern in certain nuclear proliferation discussions and treaties. Other fusion reactions produce much less energetic neutrons. D–D fusion produces a 2.45 MeV neutron and helium-3 half of the time, and produces tritium and a proton but no neutron the rest of the time. D–He

neg: Discovery of the neutron also measured how the new radiation impacted the atoms of various gases. He found that the new radiation consisted of not gamma rays, but uncharged particles with about the same mass as the proton. These particles were neutrons. Chadwick won the Nobel Prize in Physics for this discovery in 1935. The year 1932 was later referred to as the "annus mirabilis" for nuclear physics in the Cavendish Laboratory, with discoveries of the neutron, artificial nuclear disintegration by the Cockcroft–Walton particle accelerator, and the positron. Given the problems of the "proton–electron model", it was quickly accepted that the atomic nucleus is

neg: Hypernucleus been sought, as have doubly-strange nuclei containing Cascade baryons. Hypernuclei can be made by a nucleus capturing a Lambda or K meson and boiling off neutrons in a compound nuclear reaction, or, perhaps most easily, by the direct strangeness exchange reaction. A generalized mass formula developed for both the non-strange normal nuclei and strange hypernuclei can estimate masses of hypernuclei containing Lambda, Lambda-Lambda, Sigma, Cascade and Theta+ hyperon(s). The neutron and proton driplines for hypernuclei are predicted and existence of some exotic hypernuclei beyond the normal neutron and proton driplines are suggested. This generalized mass formula was named as "Samanta

neg: Neutron radiation prohibitive. Commercially, tanks of water or fuel oil, concrete, gravel, and BC are common shields that surround areas of large amounts of neutron flux, e.g., nuclear reactors. Boron-impregnated silica glass, standard borosilicate glass, high-boron steel, paraffin, and Plexiglas have niche uses. Because neutrons that strike the hydrogen nucleus (proton, or deuteron) impart energy to that nucleus, they in turn break from their chemical bonds and travel a short distance before stopping. Such hydrogen nuclei are high linear energy transfer particles, and are in turn stopped by ionization of the material they travel through. Consequently, in living tissue, neutrons have a

neg: Nuclear drip line the drip lines are typically on the order of nanoseconds or less. For alpha decay, the timescale can be much longer than for proton or neutron emission owing to the high Coulomb barrier seen by an alpha-cluster in a nucleus (the alpha particle must tunnel through the barrier). As a consequence, there are no naturally-occurring nuclei on Earth that undergo proton or neutron emission; however, such nuclei can be created, for example, in the laboratory with accelerators or naturally in stars. Such particle decays are not commonly known because particle decay is governed by the nuclear strong force, as well

neg: Weak interaction interactions. All mesons are unstable because of weak decay. In the process known as beta decay, a "down" quark in the neutron can change into an "up" quark by emitting a virtual boson which is then converted into an electron and an electron antineutrino. Another example is the electron capture, a common variant of radioactive decay, wherein a proton and an electron within an atom interact, and are changed to a neutron (an up quark is changed to a down quark) and an electron neutrino is emitted. Due to the large masses of the W bosons, particle transformations or decays

neg: Radiation hardening the gate region. It can occur even in EEPROM cells during write or erase, when the cells are subjected to a comparatively high voltage. Hard error, irreversible. While proton beams are widely used for SEE testing due to availability, at lower energies proton irradiation can often underestimate SEE susceptibility. Furthermore, proton beams expose devices to risk of total ionizing dose (TID) failure which can cloud proton testing results or result in pre-mature device failure. White neutron beams — ostensibly the most representative SEE test method — are usually derived from solid target-based sources, resulting in flux non-uniformity and small beam

neg: Accelerator Neutrino Neutron Interaction Experiment Thus both of these channels are also prone to "CC" atmospheric neutrino background. Proton decay background events predominately produce one or more neutron whereas proton decays are expected to produce a neutron only ~6% of the time Free final state neutrons are captured in the gadolinium-doped water of the detector. Even neutrons with energies ranging in the hundreds of MeV will quickly lose energy through collisions in water. Once these neutrons have been thermalized, they undergo radiative capture wherein they are incorporated into a nucleus to produce a more tightly bound state. The excess energy is given off as a

neg: Neutron number Neutron number The neutron number, symbol N, is the number of neutrons in a nuclide. Atomic number (proton number) plus neutron number equals mass number: Z+N=A. The difference between the neutron number and the atomic number is known as the neutron excess: D = N - Z = A - 2Z. Neutron number is rarely written explicitly in nuclide symbol notation, but appears as a subscript to the right of the element symbol. In order of increasing explicitness and decreasing frequency of usage: Nuclides that have the same neutron number but a different proton number are called isotones. This word

neg: Beta decay electron capture (43%) to , as it is through neutron decay by electron emission (39%) to . Most naturally occurring nuclides on earth are beta stable. Those that are not have half-lives ranging from under a second to periods of time significantly greater than the age of the universe. One common example of a long-lived isotope is the odd-proton odd-neutron nuclide , which undergoes all three types of beta decay (, and electron capture) with a half-life of . where Beta decay just changes neutron to proton or, in the case of positive beta decay (electron capture) proton to neutron

neg: Nucleon some extreme cases (cosmic rays, proton beams), they may be regarded as free protons. Neither the proton nor neutron is an elementary particle, meaning each is composed of smaller parts, namely three quarks each. A proton is composed of two up quarks and one down quark, while the neutron has one up quark and two down quarks. Quarks are held together by the strong force, or equivalently, by gluons, which mediate the strong force. An up quark has electric charge "e", and a down quark has charge "e", so the summed electric charges of proton and neutron are +"e" and

neg: Radioanalytical chemistry particle, a He nucleus. The mode of this decay causes the parent nucleus to decrease by two protons and two neutrons. This type of decay follows the relation: formula_1 Beta decay is characterized by the emission of a neutrino and a negatron which is equivalent to an electron. This process occurs when a nucleus has an excess of neutrons with respect to protons, as compared to the stable isobar. This type of transition converts a neutron into a proton; similarly, a positron is released when a proton is converted into a neutron. These decays follows the relation: formula_2 formula_3 Gamma

neg: Neutron a mass of 939,565,413.3 eV/c, or , or . The neutron has a mean square radius of about , or 0.8 fm, and it is a spin-½ fermion. The neutron has no measurable electric charge. With its positive electric charge, the proton is directly influenced by electric fields, whereas the neutron is unaffected by electric fields. The neutron has a magnetic moment, however, so the neutron is influenced by magnetic fields. The neutron's magnetic moment has a negative value, because its orientation is opposite to the neutron's spin. A free neutron is unstable, decaying to a proton, electron and antineutrino

neg: Beta particle (two up quarks and one down quark). The virtual W boson then decays into an electron and an antineutrino. β− decay commonly occurs among the neutron-rich fission byproducts produced in nuclear reactors. Free neutrons also decay via this process. Both of these processes contribute to the copious quantities of beta rays and electron antineutrinos produced by fission-reactor fuel rods. Unstable atomic nuclei with an excess of protons may undergo β decay, also called positron decay, where a proton is converted into a neutron, a positron, and an electron neutrino: Beta-plus decay can only happen inside nuclei when the absolute value

neg: Neutron from the beta decay of the neutron, when the momenta of the resulting proton and electron are measured. The total electric charge of the neutron is . This zero value has been tested experimentally, and the present experimental limit for the charge of the neutron is , or . This value is consistent with zero, given the experimental uncertainties (indicated in parentheses). By comparison, the charge of the proton is . Even though the neutron is a neutral particle, the magnetic moment of a neutron is not zero. The neutron is not affected by electric fields, but it is affected

neg: Deuterium the vibration of a chemical bond containing deuterium, versus light hydrogen. The two stable isotopes of hydrogen can also be distinguished by using mass spectrometry. The triplet deuteron nucleon is barely bound at E = , and none of the higher energy states are bound. The singlet deuteron is a virtual state, with a negative binding energy of . There is no such stable particle, but this virtual particle transiently exists during neutron-proton inelastic scattering, accounting for the unusually large neutron scattering cross-section of the proton. The nucleus of deuterium is called a deuteron. It has a mass of (equal

neg: Free neutron decay (the ionization energy of hydrogen), and therefore simply remains bound to it, as a neutral hydrogen atom (one of the "two bodies"). In this type of free neutron decay, in essence all of the neutron decay energy is carried off by the antineutrino (the other "body"). The transformation of a free proton to a neutron (plus a positron and a neutrino) is energetically impossible, since a free neutron has a greater mass than a free proton. While the neutron lifetime has been studied for decades, there currently exists a lack of consilience on its exact value, due to different results

neg: Ionizing radiation cross section. In inelastic scattering, neutrons are readily absorbed in a process called neutron capture and attributes to the neutron activation of the nucleus. Neutron interactions with most types of matter in this manner usually produce radioactive nuclei. The abundant oxygen-16 nucleus, for example, undergoes neutron activation, rapidly decays by a proton emission forming nitrogen-16, which decays to oxygen-16. The short-lived nitrogen-16 decay emits a powerful beta ray. This process can be written as: O (n,p) N (fast neutron capture possible with >11 MeV neutron) N → O + β (Decay t = 7.13 s) This high-energy β further interacts

neg: W and Z bosons neutron is converted into a proton while also emitting an electron (called a beta particle in this context) and an electron antineutrino: Again, the neutron is not an elementary particle but a composite of an up quark and two down quarks (udd). It is in fact one of the down quarks that interacts in beta decay, turning into an up quark to form a proton (uud). At the most fundamental level, then, the weak force changes the flavour of a single quark: which is immediately followed by decay of the itself: The Z boson is its own antiparticle. Thus, all

neg: Radiation hardening areas. White neutron beams also have some measure of uncertainty in their energy spectrum, often with high thermal neutron content. The disadvantages of both proton and spallation neutron sources can be avoided by using mono-energetic 14 MeV neutrons for SEE testing. A potential concern is that mono-energetic neutron-induced single event effects will not accurately represent the real-world effects of broad-spectrum atmospheric neutrons. However, recent studies have indicated that, to the contrary, mono-energetic neutrons—particularly 14 MeV neutrons—can be used to quite accurately understand SEE cross-sections in modern microelectronics. A particular study of interest, performed in 2010 by Normand and Dominik, powerfully

neg: Neutron with a mean lifetime of just under 15 minutes (). This radioactive decay, known as beta decay, is possible because the mass of the neutron is slightly greater than the proton. The free proton is stable. Neutrons or protons bound in a nucleus can be stable or unstable, however, depending on the nuclide. Beta decay, in which neutrons decay to protons, or vice versa, is governed by the weak force, and it requires the emission or absorption of electrons and neutrinos, or their antiparticles. Protons and neutrons behave almost identically under the influence of the nuclear force within the nucleus.

neg: Neutron to the protons with which it interacts in the nucleus. (However, the main attraction between neutrons and protons is via the nuclear force, which does not involve electric charge.) The simplified classical view of the neutron's charge distribution also "explains" the fact that the neutron magnetic dipole points in the opposite direction from its spin angular momentum vector (as compared to the proton). This gives the neutron, in effect, a magnetic moment which resembles a negatively charged particle. This can be reconciled classically with a neutral neutron composed of a charge distribution in which the negative sub-parts of the neutron

neg: Neutron Latin root for "neutralis" (neuter) and the Greek suffix "-on" (a suffix used in the names of subatomic particles, i.e. "electron" and "proton"). References to the word "neutron" in connection with the atom can be found in the literature as early as 1899, however. Throughout the 1920s, physicists assumed that the atomic nucleus was composed of protons and "nuclear electrons" but there were obvious problems. It was difficult to reconcile the proton–electron model for nuclei with the Heisenberg uncertainty relation of quantum mechanics. The Klein paradox, discovered by Oskar Klein in 1928, presented further quantum mechanical objections to the notion

neg: Sakata model the up, down, and strange quarks. The proton contains two up quarks and a down quark, the neutron contains one up quark and two down quarks, while the Lambda baryon contains one up quark, one down quark, and one strange quark. That is, each of these baryons is made of one up and one down quark, and an additional quark: up for the proton, down for the neutron, and strange for the Lambda baryon. Because of this correspondence to the up, down, and strange quarks, the Sakata model has the same SU(3) symmetry as the quark model, and can reproduce

neg: Delta baryon defined by having units of isospin, but with a spin quantum numbers including , , , ... . A complete listing of all properties of all these states can be found in Ref.. There also exist antiparticle Delta states with opposite charges, made up of the corresponding antiquarks. The Delta states are created when an energetic-enough probe such as a photon or pion impinges upon a proton or neutron, or possibly by the collision of an energetic-enough nucleon pair. All of the Δ baryons with mass near 1232 MeV quickly decay via the strong force into a nucleon (proton or

neg: Nuclear drip line Nuclear drip line The nuclear drip line is the boundary delimiting the zone beyond which atomic nuclei decay by the emission of a proton or neutron. An arbitrary combination of protons and neutrons does not necessarily yield a stable nucleus. One can think of moving up and/or to the right across the table of nuclides by adding one type of nucleon to a given nucleus. However, adding nucleons one at a time to a given nucleus will eventually lead to a newly formed nucleus that immediately decays by emitting a proton (or neutron). Colloquially speaking, the nucleon has 'leaked' or

neg: Karlsruhe Nuclide Chart Karlsruhe Nuclide Chart The Karlsruhe Nuclide Chart is a widespread table of nuclides in print. It is a two-dimensional graphical representation in the Segrè-arrangement with the neutron number "N" on the abscissa and the proton number "Z" on the ordinate. Each nuclide is represented at the intersection of its respective neutron and proton number by a small square box with the chemical symbol and the nucleon number "A". By columnar subdivision of such a field, in addition to ground states also nuclear isomers can be shown. The coloring of a field (segmented if necessary) shows in addition to the existing

neg: Neutron–proton ratio Neutron–proton ratio The neutron–proton ratio (N/P ratio or nuclear ratio) of an atomic nucleus is the ratio of its number of neutrons to its number of protons. Among stable nuclei and naturally occurring nuclei, this ratio generally increases with increasing atomic number. This is because electrical repulsive forces between protons scale with distance differently than strong nuclear force attractions. In particular, most pairs of protons in large nuclei are not far enough apart, such that electrical repulsion dominates over the strong nuclear force, and thus proton density in stable larger nuclei must be lower than in stable smaller nuclei where

neg: Cerium Ce can only be produced in the r-process. Another reason for the abundance of Ce is that it is a magic nucleus, having a closed neutron shell (it has 82 neutrons), and hence it has a very low cross-section towards further neutron capture. Although its proton number of 58 is not magic, it is granted additional stability, as its eight additional protons past the magic number 50 enter and complete the 1 g proton orbital. The abundances of the cerium isotopes may differ very slightly in natural sources, because Ce and Ce are the daughters of the long-lived primordial radionuclides

neg: Neutron stimulated emission computed tomography Neutron stimulated emission computed tomography Neutron stimulated emission computed tomography (NSECT) uses induced gamma emission through neutron inelastic scattering to generate images of the spatial distribution of elements in a sample. NSECT has been shown to be effective in detecting liver iron overload disorders and breast cancer. Due to its sensitivity in measuring elemental concentrations, NSECT is currently being developed for cancer staging, among other medical applications. A given atomic nucleus, defined by its proton and neutron numbers, is a quantized system with a set of characteristic higher energy levels that it can occupy as a nuclear isomer. When the

neg: Nuclear drip line can be created. In neutron stars, neutron heavy nuclei are found as relativistic electrons penetrate the nuclei and produce inverse beta decay, wherein the electron combines with a proton in the nucleus to make a neutron and an electron-neutrino: As more and more neutrons are created in nuclei the energy levels for neutrons get filled up to an energy level equal to the rest mass of a neutron. At this point any electron penetrating a nucleus will create a neutron, which will "drip" out of the nucleus. At this point we have: And from this point onwards the equation applies,

neg: Nuclear astrophysics through an unknown process in the Sun's core, hydrogen is transmuted into helium, liberating energy. Twenty years later, Bethe and von Weizsäcker independently derived the CN cycle, the first known nuclear reaction that accomplishes this transmutation. However, the Sun's primary energy source is now understood to be proton–proton chain reactions, occurring at much lower energies and much more slowly than catalytic hydrogen fusion. The interval between Eddington's proposal and derivation of the CN cycle can mainly be attributed to an incomplete understanding of nuclear structure. A proper understanding of nucleosynthetic processes only came when Chadwick discovered the neutron in 1932