| Nuclear physics |
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| Radioactive decay Nuclear fission Nuclear fusion |
Nuclear physics is the branch of physics concerned with the nucleus of the atom. Radioactive decay is the process in which an unstable Atomic nucleus loses energy by emitting ionizing particles and Radiation. Nuclear fission is the splitting of the nucleus of an atom into parts (lighter nuclei) often producing Free neutrons and other smaller nuclei which may In Physics and Nuclear chemistry, nuclear fusion is the process by which multiple- like charged atomic nuclei join together to form a heavier nucleus Physics (Greek Physis - φύσις in everyday terms is the Science of Matter and its motion. The nucleus of an Atom is the very dense region consisting of Nucleons ( Protons and Neutrons, at the center of an atom History See also Atomic theory, Atomism The concept that matter is composed of discrete units and cannot be divided into arbitrarily tiny It has three main aspects: probing the fundamental particles (protons and neutrons) and their interactions, classifying and interpreting the properties of nuclei, and providing technological advances. In Particle physics, an elementary particle or fundamental particle is a particle not known to have substructure that is it is not known to be made The proton ( Greek πρῶτον / proton "first" is a Subatomic particle with an Electric charge of one positive This article is a discussion of neutrons in general For the specific case of a neutron found outside the nucleus see Free neutron.
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Forces
Nuclei are bound together by the strong force. In particle physics the strong interaction, or strong force, or color force, holds Quarks and Gluons together to form Protons and The strong force acts over a very short range and causes an attraction between nucleons (protons and neutrons). The proton ( Greek πρῶτον / proton "first" is a Subatomic particle with an Electric charge of one positive This article is a discussion of neutrons in general For the specific case of a neutron found outside the nucleus see Free neutron. The strong nuclear force is so named because it is significantly larger in magnitude than the other fundamental forces (electroweak, electromagnetic and gravitational). In Particle physics, the electroweak interaction is the unified description of two of the four Fundamental interactions of nature Electromagnetism and the In Physics, the electromagnetic force is the force that the Electromagnetic field exerts on electrically charged particles Gravitation is a natural Phenomenon by which objects with Mass attract one another The strong force is highly attractive at only very small distances which, combined with repulsion between protons due to the electromagnetic force, allows the nucleus to be stable. The strong force felt between nucleons arises due to the exchange of gluons. In Physics a nucleon is a collective name for two Baryons the Neutron and the Proton. Gluons ( Glue and the suffix -on) are Elementary particles that cause Quarks to interact and are indirectly responsible for the The study of the strong force is dealt with by quantum chromodynamics (QCD). Quantum chromodynamics (abbreviated as QCD is a theory of the Strong interaction ( color force a Fundamental force describing the interactions of the
Nuclear models
Nucleons in the nucleus move about in a potential energy well which they themselves create arising from their interaction, and movement, with respect to each other. Nucleons can interact with each other via 2-body, 3-body or multiple-body forces. The fact that many nucleons interact with each other in a complicated way makes the nuclear many-body problem difficult to solve. The many-body problem may be defined as the study of the effects of interaction between bodies on the behaviour of a many-body system i
There broadly exist two types of nuclear models which attempt to predict and understand characteristics of nuclei. These are microscopic and macroscopic nuclear models. Microscopic nuclear models approximate the potential which the nucleons create in the nucleus. Individual interactions are combined as linear sums of potentials. Almost all models use a central potential plus a spin orbit potential. In Quantum mechanics, spin is a fundamental property of atomic nuclei, Hadrons and Elementary particles For particles with non-zero spin The difference between models is then defined by the 3-body potential used, and/or the shape of the central potential. The form of this potential is then inserted into the Schrödinger equation. Solution of the Schrödinger equation then yields the nuclear wavefunction, spin, parity and excitation energy of individual levels. In Physics, especially Quantum mechanics, the Schrödinger equation is an equation that describes how the Quantum state of a Physical system A wave function or wavefunction is a mathematical tool used in Quantum mechanics to describe any physical system In Physics, a parity transformation (also called parity inversion) is the flip in the sign of one Spatial Coordinate. Excitation is an elevation in energy level above an arbitrary baseline energy state The form of the potential used to determine these nuclear properties indicates the type of microscopic model. The shell model and deformed shell model (Nilsson model) are two examples of microscopic nuclear models. In Nuclear physics, the nuclear shell model is a model of the Atomic nucleus which uses the Pauli principle to describe the structure
Macroscopic nuclear models attempt to describe such attributes as the nuclear size, shape and surface diffuseness. Rather than calculating individual levels, macroscopic models predict nuclear radii, degree of deformation and diffuseness parameter. A simple approximation for the nuclear radius is that it is proportional to the cube root of the nuclear mass.
This implies that all nuclei are spherical and their radius is directly proportional to the cube root of their volume (volume of a sphere = 4 / 3πR3). Nuclei can also exist in a deformed shape and thus a degree of deformation ,β2, can be included to take this into account. The fact that the nucleus may not be entirely incompressible is also considered by the diffuseness parameter δ. In Thermodynamics and Fluid mechanics, compressibility is a measure of the relative volume change of a Fluid or Solid as a response An example of a macroscopic model is the droplet model of Myers and Schmidt.
Some quite successful attempts have been made to combine the microscopic and macroscopic models together. These so called mic-mac models begin with a nuclear potential, solve the Schrödinger equation and proceed to predict macroscopic nuclear parameters.
Protons and neutrons
Protons and neutrons are fermions, with different values of the isospin quantum number, so two protons and two neutrons can share the same space wave function. In Particle physics, fermions are particles which obey Fermi-Dirac statistics; they are named after Enrico Fermi. In Physics, and specifically Particle physics, isospin ( isotopic spin, isobaric spin) is a Quantum number related to the Quantum numbers describe values of conserved numbers in the dynamics of the Quantum system. A wave function or wavefunction is a mathematical tool used in Quantum mechanics to describe any physical system In the rare case of a hypernucleus, a third baryon called a hyperon, with a different value of the strangeness quantum number can also share the wave function. A hypernucleus is a nucleus which contains at least one Hyperon in addition to Nucleons The first was discovered by Marian Danysz and Jerzy Baryons are the family of Subatomic particles with a Baryon number of 1 In Particle physics, a hyperon is any Baryon containing a Strange quark, but no Charm quarks or Bottom quarks Properties
Nuclear activity
Alpha decay
Beta decay
Gamma decay
Here, a nucleus decays from an excited state into a lower state by emitting a gamma ray. Alpha decay is a type of radioactive decay in which an Atomic nucleus emits an Alpha particle (two protons and two neutrons bound together into a particle In Nuclear physics, beta decay is a type of Radioactive decay in which a Beta particle (an Electron or a Positron) is emitted Gamma rays (denoted as &gamma) are a form of Electromagnetic radiation or light emission of frequencies produced by sub-atomic particle interactions Gamma rays (denoted as &gamma) are a form of Electromagnetic radiation or light emission of frequencies produced by sub-atomic particle interactions
Fission
Fusion
History
The history of nuclear physics began with the discovery of the nucleus by Rutherford in 1911. Nuclear fission is the splitting of the nucleus of an atom into parts (lighter nuclei) often producing Free neutrons and other smaller nuclei which may In Physics and Nuclear chemistry, nuclear fusion is the process by which multiple- like charged atomic nuclei join together to form a heavier nucleus Ernest Rutherford 1st Baron Rutherford of Nelson, OM, PC, FRS (30 August 1871 – 19 October 1937 was a New Zealand Physicist While the work on radioactivity by Becquerel, Pierre and Marie Cure predates this, an explanation of radioactivity would have to wait for the discovery that the nucleus itself was composed of smaller constituents, the nucleons. In Physics a nucleon is a collective name for two Baryons the Neutron and the Proton. Attempts to split the atom led to the discovery of nuclear fission.
See also
References
External links
- Boiling Water Reactor Plant, BWR Simulator Program
- Annotated bibliography on nuclear physics from the Alsos Digital Library for Nuclear Issues
Dictionary
nuclear physics
-noun
- The branch of physics that studies the nucleus of the atom, its internal structure and components.
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