Friday, September 21, 2012

Nuclear Physics

Nuclear physics is the  study of the atomic nucleus. Nuclear physics deals mainly with the neutrons and protons makeup the nucleus and their interactions. The atomic nucleus is a relatively small dense positively charged mass at the center of an atom. It consists of positively charged protons and neutrally charged neutrons. These particles are bound together within the nucleus by residual strong nuclear force between protons and neutrons.

 The atomic nucleus is the densest part of the atom and it determines the element of each atom. The element is determined by the number of protons in the nucleus called the atomic number and its unique to each element. Meanwile the number of neutrons vary in what are called isotopes.

 Isotopes are the varieties of atoms within the same element distinguished by the number of neutrons in the nucleus and each isotope has its own set of unique properties. The particle number is number of protons and neutrons in the nucleus. The atomic weight is the mass of the isotope in atomic mass units. Another property of isotopes is its half-life is the amount time required for half of a radiometric isotope to decay. Further more a stable isotope has an infinite half-life.

The Strong Nuclear Force is the fundamental force of nature responsible for binding together the atomic nucleus. Gluons are the appropriately named particle that transmits the strong force, Gluons go back and forth between the quarks binding them togetherinto Proton and Neutron and other particles.  

The gluons binding up and down quarks into protons and neutrons also hold can decay to form a pion. This pion helps transmit a residual part of the strong force between the protons and neutrons in what is called the residual strong force or just the nuclear force.

 The Weak Nuclear Force is the fundamental force of nature that causes for several types of particle decay, It is specifically responsible for the beta decay of atomic nuclei. Negative Bata decay occurs when a neutron is turned into a proton emitting an electron an electron anti-neutrino in the process. 
Nuclear decay is event where an unstable atomic nucleus loses energy by the process of emitting an ionizing particle causing a net loss in the mass to the nucleus. 

There are two main forms nuclear decay ones found in nature, Alpha decay and Negative Beta decay.  In alpha decay the nucleus ejects a helium atomic nucleus called an alpha particle reducing the atomic number of atom by 2 changing the element. When negative Beta decay occurs a neutron emits a negatively charged electron called a beta particle and an electron anti-neutrino turning it into a proton and increasing the atomic number of the nucleus by one.

Collections of radioactive nuclei have a characteristic decay rate usually designated by the isotope's half-life. That is the time it takes half of the amount of the isotope to decay. The half-life is independent of the amount of the isotope present because the more atoms of the isotope there are the more nuclei that will decay in a given unit of time.

 Nuclear decay is often used in determining the age of a sample however there are assumptions involved in the process. It is especially assumed that the half-life of an  isotope is constant. Accelerated Nuclear Decay is the process by which nuclear decay proceeds at a faster than normal rate. Now small amounts of accelerated nuclear decay have been observed in Beta-decay under some circumstances, while accelerated alpha decay has never been directly observed evidence for it exists in the retention of radiogenic helium by zircon crystals. The main arguments against the hypothesis that the retention of radiogenic helium by zircon crystals shows substantial accelerated alpha decay is heat and the lack of an observed cause of accelerated alpha decay. However there are theoretical answers to both. The real reason for resistance to the hypothesis that the retention of radiogenic helium by zircon crystals shows substantial accelerated alpha decay is the fact that it would drastically reduce radiometric ages. However none of these arguments change the fact that measured helium diffusion rates in zircon crystals are a perfect match to a model showing accelerated alpha decay about six thousand years ago.


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