Artificially induced radioactivity

This misuse of the word radioactivity causes many people to incorrectly think of radioactivity as something one can get by being near radioactive materials. There is only one process which behaves anything like that, and it is called artificially induced radioactivity, a process mainly carried out in research laboratories. When some materials are bombarded with protons, neutrons, or other nuclear particles of appropriate energy, their nuclei may be transmuted, creating unstable isotopes which are radioactive. 

Nuclear Reactions and Artificially Induced Radioactivity—Radioactive nuclides can be synthesized by nuclear reactions in which target nuclei are bombarded with energetic particles such as a particles or neutrons. More than 1000 radioactive nuclides have been produced in this way. Many of them have important practical applications. 

Radioactivity, Induced—Radioactivity produced in a substance after bombardment with neutrons or other particles. The resulting activity is "natural radioactivity" if formed by nuclear reactions occurring in nature and "artificial radioactivity" if the reactions are caused by man. 

The number of protons is unique to the element but most elements can exist with two or more different numbers of neutrons in their nucleus, giving rise to different isotopes of the same element. Some isotopes are stable, but some (numerically the majority) have nuclei which change spontaneously - that is, they are radioactive. Following the discovery of naturally radioactive isotopes around 1900 (see Section 10.3) it was soon found that many elements could be artificially induced to become radioactive by irradiating with neutrons (activation analysis). This observation led to the development of a precise and sensitive method for chemical analysis. 

In 1934 the Hungarian physicist Leo Szilard filed a patent with the British Patent Office. It was based on an idea, nothing more - an idea about how to harness nuclear energy. The Joliot-Curies had shown that bombarding nuclei with particles can induce radioactive decay artificially. And the work of Bothe and Chadwick had demonstrated that some radioactive nuclei emit neutrons. So what would happen if neutrons induced nuclear decay that led to more neutrons The result might be a chain reaction a self-sustaining release of nuclear energy. 

Since not many natural radioactive elements are in existence analysis by radiochemical methods was rather limited until it became possible to "induce radioactivity artificially in some of the non-radioactive elements, as was first done in 1934 by I. Curie F.Joliot(Ref 1). This discovery greatly broadened the application of radiochemical analysis. The first application of artificial radio activation for the identification of constituents in a mixt was reported by Meinke (Ref 16) to have been done in 1936 by Hevesy 8t Levi (Ref 2). 

Sometimes the nucleus can be changed by bombarding it with another type of particle. This is referred to as induced radioactivity. In 1934, Irene Curie, the daughter of Pierre and Marie Curie, and her husband, Frederic Joliot, announced the first synthesis of an artificial radioactive isotope. They bombarded a thin piece of aluminum foil with ot-particles produced by the decay of polonium and found that the aluminum target became radioactive. Chemical analysis showed that the product of this reaction was an isotope of phosphorus. 

Scientists have learned how to make some isotopes undergo nuclear reactions. Artificial radioactivity is induced by bombardment of certain nuclei with subatomic particles (or atoms), which are produced either by other nuclear reactions or in machines called particle accelerators. For example, the first artificially induced nuclear reaction was produced by Ernest Rutherford (1871-1937) in 1919 ... 

Which of the following reactions represent natural radioactive decay, and which are artificially induced ... 

They could not chemically trace the infinitesimal accumulation of silicon. Joliot explained why in 1935, when he and his wife accepted the Nobel Prize in Chemistry for their discovery The yield of these transmutations is very small, and the weights of elements formed. .. are less than 10 [grams], representing at most a few million atoms —too few to find by chemical reaction alone. But they could trace the radioactivity of the phosphorus with a Geiger counter. If it did indeed signal the artificial transmutation of some of the aluminum to phosphorus, they should be able to separate the two different elements chemically. The radioactivity would go with the new phosphorus and leave the untransmuted aluminum behind. But they needed a definitive separation that could be carried out within three minutes, before the faint induced radioactivity faded below their Geiger counter s threshold. 

The radioactivity of nuclides produced in this marmer is known as artificial radioactivity or induced radioactivity. Artificial radionuclides behave like natural radioactive elements in two ways They disintegrate in a definite fashion and they have a specific half-life. The Joliot-Curies received the Nobel Prize in chemistry in 1935 for the discovery of artificial, or induced, radioactivity. 

Radioactivity. A natural or artificially induced process consisting of electromagnetic or particle radiation from an atomic nucleus. 

The chemical composition of slime as well as the secretion kinetics of unlabelled and radioactively labelled slimes during naturally occurring and artificially induced spherulation of Physarum polycephalum have been reported. ... 

Disco very 0/ phenomenon of induced or artificial radioactivity) 2)G.von Hevesy H.Levi, KglDanskeVidenskabSelskabMatfys Medd 14, 5(1936) 3)0.Hahn, "Applied... 

Frederick Joliot and Irene Curie discussed the "/-rays emitted in association with neutrons by berillium irradiated with a particles and reported to have observed under the same conditions also the emission of fast positrons. The origin of these particles was not yet clear at the time of the Solvay Conference. It was understood by the same authors a few months later when they discovered the artificial radioactivity induced by a-particle bombardment which normally takes place by emission of positrons. 

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