Radioactivity

          Several thousand years ago, a Greek philosopher named Democritus was enjoying the smell of some bread when he started to  Radioactivity think about how, if the bread was cut, he would have some smaller  pieces. Then, if he cut those, he would have even smaller pieces.

          And, as he kept cutting, the pieces would get smaller and smaller and smaller. So, Democritus wondered, how many times could he cut the bread? It occurred to him that he could not just keep cutting the bread forever; at some point, the bits of bread would be so small that they simply could not be cut any more. He thought that it made sense to think that there was a size limit—that he could only make pieces of bread that were so small, but no smaller. When he got to the smallest piece—the piece that could not be cut any further—Democritus called it uncuttable”; the Greek word for this is atom. Human understanding of atoms has changed a lot in the last fewthousand years.

           The actual world of atoms is far more interesting, and harder to  understand, than the ancient Greeks could comprehend. There is not just one type of atom— there are now over 115 known varieties. Atoms can join together into larger units known as  molecules. Bread, for example, is made of many kinds of atoms and molecules. Plus, atoms are,  in reality, “cuttable.” It is possible to split atoms into pieces, unleashing.

           Radioactivity is a property of atomic core decay spontaneously to the emission of alpha, beta, gamma. Some nuclei spontaneously emit particles or radiation inside them which exist or occur in processes that occur there. Therefore, such core are unstable, or radioactive.

            Following experiments established that the mass of the atom and all positive charge is concentrated in a small volume in the center of the atom, called the atomic nucleus area (consisting of protons and neutrons). Revolve around a number of core electrons compensates the positive charge nucleus.

            The phenomenon of radioactivity, although spontaneous, not going out of time: there is life, called average life of the nuclei of an element, then the remaining number of decayed nuclei is reduced.

             Antoine Henri Becqurel, French physicist, scholar, was born in 1852 in a family of famous physicists. Very much concerned about physical problems, especially the problem of fluorescence, Becquerel gave a very interesting discovery by Roentgen of radiation X, which led eventually to the discovery of radioactivity phenomenon. The importance of this finding is revealed by the words of the great scientist Albert Einstein and "The phenomenon of radioactivity is the most revolutionary force of technical progress, the discovery of fire by prehistoric man until today."

     Α-ray experiences bombing in 1934 led to a new discovery of primary importance. It is discovered artificial radioactivity by Frederic and Irene Joliot-Curie wife, son-and daughter of the discoverer of polonium and radium. In 1934 they were subjected to α-ray bombardment some aluminum foil. They noted that during the bombing, aluminum emitted neutrons. When the bombing stopped, aluminum foils and they stopped issuing further neutrons, aluminum foils but continued to emit radiation rays similar to β.

             After much research, Joliot-Curie  have clear what happens: the action of α rays, aluminum core issue in a core of radioactive phosphorus that is not likely.

Similarly, by transmuting the element magnesium and boron Joliot-Curie  have obtained a radioazot radiosiliciu respectively. Discovery about the possibility of creating artificial radioactive isotopes of various elements of the response also had a high natural radioactivity as the discovery 36 years ago. Putting this idea into practice,  physicist Ernico Fermi bombarded 60 different elements and 40 of them gave rise to artificial radioactive isotopes with half-lives caught between a few seconds and a few days.

              Most people know about the atom bombs that destroyed Hiroshima and Nagasaki at the end of World War II, and many know that the operation  that brought these bombs into existence was called the Manhattan Project. But few people know the full story that led to that massive endeavor: How uranium was discovered, how its properties were investigated, and how a fierce competition among several groups of scientists in different countries brought us a deeper understanding of uranium. Few people know that it is the atom of the element uranium that undergoes the unusual process of fission—by simply splitting in two when it is hit by a tiny subatomic particle.

               The nuclear fission reaction releases energy hidden in the depths of the nucleus. In an act of nuclear fission was calculated how much energy is released for Uranium-235:

• fission products: 166 MeV (82.5%)

• fission radiation: 6 MeV (2.95%)

• Radiation: 7 MeV (3.4%)

• neutrinos: 11 MeV (5.4%)

• Delayed radiation: 6 MeV (2.95%)

• Neutrons: 5 MeV (2.8%)

               Thus, 1 kg uranium-235 contains a number of 6.0 • 1023 / 0.235 cores and evolved fisionare  5 • 1026 MeV 1016 J. Energy equivalent to 1016 J of heat released by burning 300,000 tonnes of coal.

               The use of uranium in nuclear power is undoubtedly the main use of this item. Uranium, Uranium in Latin, is a chemical element, a metal, actinide series of the periodic elements having chimic U symbol and serial number 92. Uranium has the highest atomic weight of all natural elements. Uranium is approximately 70% denser than lead and is slightly radioactive. Its natural distribution is approximately a few parts per million in soil, rocks and water.

               Uranium exists in Earth's crust, up to a depth of 16 km, with an average abundance of 2 * 10-5% exceeding the abundance of metals such as mercury, silver, bismuth and cadmium. The waters of the ocean there is uranium in the form of soluble salts, with concentrations ranging from 0.4 * 10-7 and 23 * 10-7g/l. Is known that are three types of rocks that may contain uranium. The first two contain secondary and primary mineral component  third category contains uranium as an  impurity included in the crystalline base.

              The most common types of radiation are called alpha, beta, and gamma radiation, but there are several other varieties of radioactive decay.

          ALPHA RADIATION

               Composed of two protons and two neutrons, the alpha particle is a nucleus of the element helium. Because of its very large mass (more than 7000 times the mass of the beta particle) and its charge, it has a very short range. It is not suitable for radiation therapy since its range is less than a tenth of a millimeter inside the body. Its main radiation hazard comes when it is ingested into the body; it has great destructive power within its short range. In contact with fast-growing membranes and living cells, it is positioned for maximum damage.

          BETA RADIATION

                More than half of the natural radioactive nuclizii have beta activity. Beta radiation consists of electrons or positrons moving at high speeds that are called radiation.

       

GAMMA

     Are not particulate radiation like the alpha and beta, but a form of high-energy electromagnetic wave.

         These rays are not affected by electric or magnetic field. They are electromagnetic in nature and are subject to reflection phenomena of refraction, diffraction and interference.