Radiation physics
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Radiation physics






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  • Radiation is the energy that is given off by the radioactive atom. Eg. Carbon 14, Uranium 238, etc <br /> How does radiation work. To understand this you need to understand fundamental forces. <br />
  • This appear is a nucleus. The red ones are going to be the protons and the blue ones are going to be the neutrons. If we look at the periodic table, we can see neon have same number of proton and neutro, similar way calcium also have same no. of neutrons and protons. Sn (tin) have 50 P and 70 N. so here number of proton is less compare to the number of neutrons. Uranium have 92P and 146N. Why is that??? The reason is nucleus is held together by a strong nuclear force. All these nucleons are held together by this force which hold the nucleus together. Nucleus loves to shed apart. The reason is it has positive charges, when number of it is small there will be a strong nuclear forces to hold it together. In U, it has 146N to hold the 92P. <br />
  • Why they emit radiation spontaneously?? It is because the unstable atomic radius wants to give some energy in order to shift to more stabel configuration. <br />
  • Radiation is classified into two groups. Non ionizing and ionizing radiation. Matter can be ionized directly and indirectly. Direct ionizing particles are charged particles. They include electrons, protons, alpha particles and heavy ions. (A charged microscopic particle that forms when an ion attaches to a dust mote or similar object). Neutral particles ionize matter indirectly. Neutral particles include photons ( x-rays and Y-rays) and neutrons. <br /> Both of these types of radiation can be harmful, but these both types of radiation are used in treatment of cancer. <br /> The branch of medicine that uses radiation is called radiotherapy. <br />
  • 1. They do not have enough energy to completely remove an electron from an atom or molecule. <br />
  • Unstable atoms emits radiation. The types of ionization radiation include alhpa radiation, beta radiation, gamma rays, x rays and neutrons <br />
  • Alpha radiation is the emission of alpha particles during radioactive decay. Radioactive decay is a process of decomposition of a radioactive substance. During alpha decay alpha particles are emitted. Alpha particles consists of two protons and two neutrons bound together into a particles identical to helium nucleus. So alpha decay is simply the emission of helium atom. <br /> e.g. …… the uranium-238 nucleus emits the helium nucleus (that is the alpha particle) and as a result the parent nucleus become thorium-234. Here mass number of parent nucleus (U) has been reduced by 4 and atomic number is reduced by 2. this is one of the characteristic of alpha decay for any nucleus in which it occur. <br />
  • After emitting the alpha particles the atoms continue to a chain of radioactive decay. During this process atom will be transformed to other isotopes until the atom become non radioactive isotope. (radon, polonium, lead, bismuth) (this is just to show it has chain reaction) <br />
  • Alpha radiation is the least penetrating. It can be stopped (or absorbed) by a sheet of paper. when alpha particles are emitted outside our bodies, virtually all of their ionizing radiation is harmlessly absorbed by the nonliving outer layer of our skin. This means that alpha radiation doesn’t have much effect on our health unless radioactive isotopes get inside our bodies and emit radiation internally . <br />
  • Because they lose all of their energy in a small volume. Alpha particles are effective only for a short distance because they use up their energy when they hit other atoms. <br />
  • How it damage DNA (explain) <br />

Radiation physics Radiation physics Presentation Transcript

  • RADIATION PHYSICS Presented by: Fathimath Shibana Msc. Biotechnology First semester 2012 University of Mysore Guided by: Dr. H.S. Aparna Associate professor DOS in Biotechnolog
  • Radiation : It is defined as the process by which energy is emitted from a source and propagated through the surrounding medium.
  • Radioactivity : It is the act of emitting radiation spontaneously from the unstable atoms.  Unstable atoms differ from stable atoms because they have an excess of energy or mass or both.  Unstable atoms are known as radioactive atoms. E.g. Carbon 14, Uranium 238
  • CLASSIFICATION OF RADIATION Radiation Non-ionizing Ionizing Directly ionizing (charged particles: electrons, protons, etc Indirectly ionizing (neutral particles: photons, neutrons.
  • NON-IONIZING RADIATION Non-ionizing radiation refers to any type of electromagnetic radiation that does not carry enough energy to ionize an atom or molecule. Near ultraviolet radiation infrared radiation, microwave, radio waves, etc 
  • IONIZING RADIATION      Ionizing radiation has sufficient energy to ionize an atom or molecule. Ionization is a process in which a charged portion of a molecule (usually electron) is given enough energy to break away from the atom. Ionization results in the formation of charged particles or ions; the molecule with net positive charge and the free electron with a net negative charge. All ionizing radiation is capable, directly and indirectly of removing electrons from most of the molecules. Ionizing radiation has enough energy to damage DNA in cells which in turn may lead to cancer.
  • Characteristics of alpha radiation:   Alpha radiation is not able to penetrate skin. Alpha emitting materials can be harmful to humans if the materials are inhaled, swallowed or absorbed through open wounds.
  • Alpha radiation travels a very short distance through air.  A variety of instruments have been designed to measure alpha radiation. Instruments can not detect alpha radiation even a thin layer of water, blood, dust, paper or other material, because alpha radiation is not penetrating 
  • USES OF ALPHA RADIATIONS Alpha particles are most commonly used in smoke alarms (smoke detectors). The alpha particles ionize air between a small gap. A small current is pass through the ionized air. Smoke particles from fire that enter the air gap reduces the current flow, sounding the alarm.  Alpha decay can produce safe power sources for radioisotope thermoelectric generators used for space probes and artificial heart pacemakers. 
  • BETA RADIATION  Beta radiation is a stream of electrons called beta particles. When a beta particle is ejected, a neutron in the nucleus is converted to a proton, so the mass number of nucleus is unchanged, but the atomic number increases by one unit.
  •  Beta radiation is more hazardous because it can also cause ionization of living cells. If the particles hits a molecule of DNA it can cause spontaneous mutation and cancer. Characteristics of beta radiation: Beta radiation may travel meters in air and is moderately penetrating.  It can penetrate human skin to “germinal layer” where new cells are produced. 
  • Beta emitting contaminants may be harmful if deposited internally  Most beta emitters can be detected with survey instruments. (e.g. CD-V-700). Some beta emitters, however produce very low energy, poorly penetrating radiation that may be difficult or impossible to detect. Examples of these are carbon-14, tritium, and sulfur-35. 
  •  Beta radiation cannot be detected with an ionization chamber such as a CD V-715.  Clothing and turnout gear provide some protection against most beta radiation. Turnout gear and dry clothing can keep beta emitters off of the skin.
  • USES OF BETA RADIATIONS Beta radiation are widely used in medicine. In branchy therapy, beta radioisotopes can be used to irradiate areas inside a patient to prevent the growth of certain tissues. Beta particles are also used in some forms of therapy to kill cancer cells.  Beta particles are used in quality control to test the thickness of an item, such as paper, coming through a system of rollers. 
  • Beta radiation is used in leak detection in the pipeline. This is achieved by adding small amount of beta radiation to the fluid. The area above the ground where high intensity of beta radiation is detected will pin point the leak sources in the pipeline.  Carbon-14 is used as tracers in chemical and biological research. The age of the ancient organic materials can also be found by measuring the amount of Carbon-14 that is left. 
  • GAMMA RADIATION Gamma radiation is electromagnetic radiation of high frequency and therefore high photons with a very short wavelength.  The emission of gamma radiation results from an energy change within the atomic nucleus.  Gamma radiation change neither the atomic number nor the atomic mass.  Alpha and beta emission are often accompanied by gamma emission, as an excited nucleus drops to a lower and more stable energy change. 
  • X-RAYS X-ray photons carry enough energy to ionize atoms and disrupt molecular bond.  This makes it a type of ionizing radiation and thereby harmful to living tissues.  X-ray machine sends individual x-ray particles through the body. The image is recorded on a computer or film. 
  • Characteristics of gamma radiation and x-rays: Gamma radiation and X-rays are electromagnetic radiation like visible light, radio waves, and ultraviolet light. These electromagnetic radiations differ only in the amount of energy they have. Gamma rays and X-rays are the most energetic of these.  X-rays are like gamma rays. They, too, are penetrating radiation. 
  •  Gamma radiation is able to travel many meters in air and many centimeters in human tissue. Radioactive materials that emit gamma radiation and Xrays constitute both an external and internal hazard to humans  Gamma radiation or X-rays frequently accompany the emission of alpha and beta radiation 
  • Gamma radiation is detected with survey instruments, including civil defense instruments. Low levels can be measured with a standard Geiger counter, such as the CD V-700. High levels can be measured with an ionization chamber, such as a CD V-715.  Instruments designed solely for alpha detection will not detect gamma radiation  Pocket chamber (pencil) dosimeters, film badges, thermo luminescent, and other types of dosimeters can be used to measure accumulated exposure to gamma radiation. 
  • USES OF GAMMA RADIATIONS  Even after it has been packaged, gamma rays can be used to kill bacteria, mould and insects in food. This process prolongs the shelf-life of the food, but sometimes changes the taste.  Gamma rays are also used to sterilise hospital equipment, especially plastic syringes that would be damaged if heated.
  • The most common tracer is called Technetium-99 and is very safe because it only emits gamma rays and doesn't cause much ionization. • Radioisotopes can be used for medical purposes, such as checking for a blocked kidney. To do this a small amount of Iodine-123 is injected into the patient, after 5 minutes 2 Geiger counters are placed over the kidneys. • Also radioisotopes are used in industry, to detect leaking pipes. To do this, a small amount is injected into the pipe. It is then detected with a GM counter above ground. 
  • Checking welds. If a gamma source is placed on one side of the welded metal, and a photographic film on the other side, weak points or air bubbles will show up on the film, like an X-ray.  Because Gamma rays can kill living cells, they are used to kill cancer cells without having to resort to difficult surgery. This is called "Radiotherapy", and works because cancer cells can't repair themselves when damaged by gamma rays, as healthy cells can 
  • USES OF X-RAYS  X-rays are used in medicine for medical analysis. Dentists use them to find complications, cavities and impacted teeth. Soft body tissue are transparent to the waves. Bones also block the rays.  X-rays are used in industry to inspect products made by various kinds of materials. X-ray machines are used in airports to check luggage etc.
  •  In Science x-rays are used to analyze the arrangement of atoms in many kinds of substances, particularly crystals. Archaeologists used X-rays to examine ancient objects covered by a crust of dirt.  X-rays are also used in consumer goods the manufactures treat certain kinds of plastic to check the quality of many mass produced products.
  • REFERENCES  http://www.darvill.clara.net/nucrad/uses.htm  http://www.youtube.com/watch?v=oFdR_yMKOCw&feature=related  http://www.ksre.ksu.edu/agsafe/p.aspx?tabid=47  http://www.bbc.co.uk/schools/gcsebitesize/science/ocr_gateway_pre_20 11/living_future/4_nuclear_radiation1.shtml  http://www.nuc.berkeley.edu/News/HTW/radiation-basics  http://en.wikipedia.org/wiki/Ionizing_radiation  http://johnjackson.hubpages.com/hub/The-Three-Types-of-Radiation  http://chemistry.about.com/od/chemistryfaqs/f/radioactivity.htm  http://en.wikipedia.org/wiki/X-ray  http://www.stmary.ws/highschool/physics/xray_1.htm