Monday, 21 September 2015

Introduction To Nuclear Physics



NUCLEAR PHYSICS
introduction to nuclear physics
nucleus, nuclear constituents, nuclear fusion and fission
Nuclear physics is a branch of physics dealing with the nucleus of an atom its constituent, the nuclear forces and the reactions involving the nucleus and its constituents.
A nucleus is cluster of protons and neutrons found in the center of an atom. It is positively charge and containing the mass of the whole atom. It has an approximate diameter of 10-14cm. it was first discovered by Lord Rutherford in his alpha scattering experiment.
Constituent of the nucleus
the nucleus of any atom basically contain the protons and the neutrons as the fundamental particles, though other particles may be born out of the nucleus but they do not exit independently. The nucleus is positively charge; in the nucleus protons is positively charge while the neutrons are electrically neutral with almost equal masses. Both protons and neutrons are referred to as nucleons .the sum of the nucleons gives the atomic mass of the atom while the number of the protons is the nuclear charge.
Nucleons And Their Respective Charge and Masses
Particle charge masses
electrons -1.6*10_19c 9.11*10-31
protons 1.6*10_19c 6.67*10-27
neutrons 0 6.67*10-27
Nuclear forces : The nucleus consist of protons which are positively charged and neutrons which are electrically neutral ; according to electrostatic law these protons are suppose to move apart or repel each other b force due to coulomb thereby collapsing the nucleus but in reality this does not happen. Why? Research shows that there must exist a force that is strong enough to overcome this Coulomb force and keep the nucleons together. This special force is the nuclear force.
Therefore a nuclear force is a force that keeps the nucleons in the nucleus of an atom together or in other is the force that overcomes the coulomb’s force (of repulsion) between the protons in the nucleus of an atom. This force is neither electrostatic, magnetic nor gravitational, the nature of nuclear force is yet known but serious research is still going.
This force is very large in magnitude and more than electrical or gravitational forces. This is why in normal reactions (i.e. chemical reaction) nucleons are not affected and this is why it need large amount of energy to break a nucleus.
Nuclear Reactions: A nuclear reaction is a reaction involving the nucleons of an atom or nuclide. Any reaction altering the number of protons or neutrons of an atom is termed as nuclear reaction. Nuclear reactions the protons is mostly accompanied with loss in mass, change in masses, changes in atom, release of energy, and some radiations.
Form of Nuclear of Nuclear Reactions: form refers s to how the nuclear reaction takes place. Basically there are six form of nuclear reactions; namely:
(1) Scattering: when the product and reactant are same. Example alpha scattering experiment by Lord Rutherford.
(2) Transmutations: when there is a change in the at the end of the reactions , either by neutron, 10n, proton 1 1H, alpha α, etc
(3) Photo Disintegration e.g. gamma
(4) artificial transmutation
(5) Radioactive Capture
(6) induced fission by fast or slow moving neutron.
Types of Nuclear Reaction
there are basically two types of reactions via; fission and fusion nuclear reactions.
Fission nuclear reaction occurs when a large nuclear called targeted nuclide is being shot by a small particle like neutron called a projectile. The large nuclide will disintegrate into two or more smaller nuclide with the release of energy and several neutrons. When the large nuclide is fast hited by the neutron it becomes unstable and we called it complex nuclide. This nuclide cannot remain in this unstable stage, it disintegrate in two or more nuclide with the release o energy.
Nuclear chain reaction occurs when there are available neutrons and the given nuclide reaches a certain critical mass. Critical mass is minimum amount of nuclide (e.g. uranium) required below which
23592 U + n = 236 92U* = 147 57La + 87 57Br + 2n
Fusion nuclear reaction: fusion reaction occur when two light nuclide come together and fuse together to form a single nuclide releasing enormous amount of energy and radiations. Fusion reaction requires activation energy to start. e.g.
13 6C + 42 H = 168 O + n +17.6MeV.
TERMS IN NUCLEAR PHYSICS
Nuclide: is any nuclear specie with a definite number of proton number and mass number.
Nuclei: is plural of nuclide.
Isotopes: are two or more nuclei of same atom with same proton number
see photo of solar water heater constructed by unimaid student

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