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Alpha, Beta, Gamma Radioactive Decay Source Unknown
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| Radioactive decay is a process of discharging radioactive
particles. When talking about radiation, this article refers to ionizing
radiation. Different types of radioactive decay include alpha, beta, and
gamma decay. They are named after the particles emitted during this process.
During the decay the radioactive particles take the energy away from the
nucleus. Some radioactive decay changes the original nucleus of the atom
into either a different nucleus or a nucleus in a changed state. Types Of Radioactive Decay Alpha Decay Alpha particles, emitted during alpha decay, are made of two neutrons and two protons. Their structure is similar to a helium nucleus. Most alpha particles created by alpha decay do not have high penetration, compared to other particles. Even a sheet of paper can stop them. Alpha particles pose little threat externally because even air can stop them if the wall of air between the radioactive source and the object is wide enough. Skin also stops alpha particles from entering the body. They are very dangerous to living organisms when taken internally, however — much more so than beta or gamma ones. Alpha particles emitted from Polonium-210 are notorious for having been used in murdering a former officer of the Russian secret service, Alexander Litvinenko, in 2006. He was tricked to ingest Polonium-210 in his food during a lunch meeting. It was a widely publicized case, especially because Litvinenko was poisoned in the United Kingdom, where he received political asylum. Beta Decay Beta particles, created during beta decay, are positrons or electrons. They have higher penetration than alpha particles, but they cannot penetrate aluminum, as well as a range of other materials. Beta radiation can enter the body during direct exposure. It is used in radiotherapy. An interesting aspect of beta decay is that sometimes the particles that travel at high speed emit beautiful blue light, called Cherenkov radiation. An example of this was the glow of caesium-137 that attracted people during the Goiânia accident described below. It was because of this glow that at the time of the accident people thought that caesium-137 was a magical substance and displayed it in their houses. Gamma Decay Gamma rays created during gamma decay have very high level of penetration, much higher than the penetration capacity of alpha and beta particles. To protect against gamma radiation one needs to use a shield made from lead or another heavy material. The definition of gamma rays changed a number of times but now they are defined as rays that the nucleus emits, except for gamma rays emitted during astronomic events. They are distinguished from X-rays, which are created by the emission from electrons that are not inside the nucleus. Half-Life Each radioactive particle has a half-life, defined as a duration of time in which the total amount of the radioactive substance decreases by half. It represents time and is measured in seconds, minutes, hours, days, years, depending on the duration of the half- life. For example, the radioactive particles of iodine-131 and Caesium-137, that were some of the major substances that contaminated the surrounding area after the Chernobyl accident, have half-lives of 8 days and 30 years, respectfully. The total amount of time it takes for the radioactive material to decay will depend both on its half- life and on the amount of the material. |
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