Nuclear reactions positron emission

C22-0094. Two isotopes used in positron-emission imaging are C and O. On which side of the belt of stability are these nuclides located Write the nuclear reactions for their disintegrations. 

C22-0099. Complete the following nuclear reactions (a) positron emission from Si (b) electron capture by... 

X 109 years and decays by positron (+°P) emission. Write the equation for this nuclear reaction. 

At very high temperatures, above 3 or 4 billion k, silicon is consumed so quickly that positron emission and electron capture reactions which might modify the n/p ratio are largely short-circuited. The weak interaction does not have time to convert any appreciable fraction of protons into neutrons during the brief period of thermonuclear combustion. It follows that, starting with matter that is initially dominated by nuclei containing equal numbers of neutrons and protons, such as oxygen-16 and silicon-28, the final products must conserve Z = N, unless they move away from nuclear stability beyond calcium-40, the last stable a element. 

Another important characteristic is that ion beams can produce a variety of the secondary particles/photons such as secondary ions/atoms, electrons, positrons. X-rays, gamma rays, and so on, which enable us to use ion beams as analytical probes. Ion beam analyses are characterized by the respectively detected secondary species, such as secondary ion mass spectrometry (SIMS), sputtered neutral mass spectrometry (SNMS), electron spectroscopy, particle-induced X-ray emission (PIXE), nuclear reaction analyses (NRA), positron emission tomography (PET), and so on. 

Positrons can be produced by either nuclear decay or the transformation of rhe energy of a gamma ray into an electron-positron pair. In nuclei that are proton-rich, a mode of decay that permits a reduction in the number of protons with a small expenditure of energy is positron emission. The reaction taking place during decay is... 

The first of these equations shows that the result of the nuclear reaction in which aluminum is bombarded with or-partides is the emission of a neutron and the production of a radioactive isotope of phosphorus. The second equation shows the radioactive disintegrations of the latter to yield a stable silicon atom and a positron. Continuation of this line of investigation by several research groups confirmed that radioactive nuclides are formed m many nuclear reactions. 

The fifth type of radioactive emission, gamma radiation, does not result in a change in the properties of the atoms. As a result, they are usually omitted from nuclear equations. Gamma emissions often accompany other alpha or beta reactions—any decay that has an excess of energy that is released. For example, when a positron collides with an electron, two gamma rays are emitted, a phenomenon usually referred to as annihilation radiation. 

The positron has a short life and will quickly be annihilated in a reaction with an electron, producing y-photons of characteristic energy (0.51 MeV). In addition, the basic nuclear process itself is usually accompanied by the emission of gamma radiation. As in the case of negatron decay a complete energy balance reveals a discrepancy which can be accounted for if the emission of a further particle—the neutrino, v is postulated. Overall, positron emission can be summarized in a general equation... 

Cobalt-60 is used for radiation treatments of certain cancers. It decays by positron emission. Write a nuclear equation for the reaction. 

Nowadays, nuclear medicine has become an indispensible section of medical science, and the production of radionuclides and labelled compounds for application in nuclear medicine is an important branch of nuclear and radiochemistry. The development of radionuclide generators made short-lived radionuclides available at any time for medical application. New imaging devices, such as single photon emission tomography (SPET) and positron emission tomography (PET) made it possible to study local biochemical reactions and their kinetics in the living human body. 

Another medical procedure that uses nuclear reactions is called positron emission tomography (PET), which is shown in Figure 20. PET uses radioactive isotopes that have short half-lives. An unstable isotope that contains too many protons is injected into the person. 

Determine whether each of the following nuclear reactions involves alpha decay, beta decay, positron emission, or electron capture. 

Write a balanced nuclear equation for the reaction in which oxygen-15 undergoes positron emission. 

C-Labelled phosgene is a useful material in radiopharmaceutical and nuclear medical applications, since it combines the radiophysical properties of C with the extensive reaction chemistry of phosgene to permit the rapid synthesis of a wide range of biologically-active materials with radiochemical labels. Carbon-11 is a short-lived positron-emitting radionucleide, useful for in vivo measurements with positron emission tomography (PET) [519], Because of... 

On Stan s way to the hospital, he passes a nuclear power plant that generates electricity for the homes and businesses in his city by means of yet another kind of nuclear reaction. When Stan gets to the hospital, Fred shows him the equipment he is using in his research. It is a positron emission tomography (PET) machine that allows Fred to generate images showing which parts of... 

Oxygen-13 atoms undergo positron emission, so they can be used to generate PET scans. Write the nuclear equation for this reaction. 

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