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In short, neutron capture is a nuclear reaction wherein an atomic nucleus captures one (or perhaps more) neutrons. The nucleus is then one nucleon heavier (or perhaps more, if more neutrons are absorbed). The new nucleus may be subject to further transformations, depending on what was formed in the capture process.
Many different atomic nuclei can capture a neutron under the right conditions. We often think of uranium or plutonium (nuclear fuels) as atoms that undergo neutron capture. It is, after all, neutron capture that destabilizes the nucleus and can cause nuclear fission. This is the process that we set up when we build a nuclear reactor or a nuclear weapon.
We can expose any number of different materials to the neutron flux in operating nuclear reactor. Atoms in the material will undergo neutron capture, depending on the conditions in the ractor, and (primarily) what the material is. In the case of cobalt, we will lower a measured amount of the metal in a suitable form into the reactor via a port. After a desired amount of time, the slug of cobalt, which was cobalt-59, is withdrawn. We now have a slug that has a fair percentage of cobalt-60 in it, and cobalt-60 is radioactive. The isotope emits gamma rays, and the slug is put in a casket of shielding material and can be transported for industrial use. (It might be used to X-ray welds in piping at a remote location, or sterilize band aids or other medical items at the end of a manufacturing process.)
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What causes a splitting nucleus?
The capture of a neutron can split a nucleus - but only for certain isotopes like U-235 and Pu-239. Two naturally occurring isotopes undergo spontaneous fission, meaning the nucleus splits without neutron capture. These are 235U and 238U. A few other isotopes undergo spontaneous fission, but these are produced by an earlier neutron capture. Spontaneous fission is the result of quantum tunnelling, which is rather difficult to explain. There are related links below.
How can the rate of reaction be slowed down in a nuclear fission reactor?
By inserting the control rods which absorb neutrons using boron, cadmium, or other material with a large neutron capture crosssection. If the reactor should begin to run out of control the SCRAM system will suddenly insert large amounts of neutron absorbing material, instantly stopping the neutron chain reaction.
What particle is captured by other nuclei in a nuclear chain reaction triggering additional fission events?
The neutron is the particle that undergoes those capture events resulting in fission.
What is positron capture?
The decay of an unstable atom by absorbing a wandering positron into the nucleus, converting a neutron into a proton. One example is how a radioactive form of iodine, 131I, can use positron capture to become xenon, 131Xe. This is a stable, so the conversion is a big help.
What does neutron absorbtion accomplish in a nuclear reactor?
It is the absorption or capture of slow neutrons by the uranium nucleus that causes it to fission and release energy, so it is the essential factor that makes nuclear energy work
What the process by which an atom bombarded by a neutron becomes another isotope of the same element?
Neutron Capture.
What is a proton in the nucleus converted into what during electron capture?
During electron capture, an electron and proton combine and are converted to a neutron.
In a nuclear fission reaction a freely moving neutron?
In a nuclear fission reaction, a freely moving neutron undergoes neutron capture and initiates the nuclear fission of a fuel atom.
What Is geological electron capture?
Electron capture occurs when an electron from the innermost orbital of an atom is captured by a nucleus, which leads to the conversion of a proton into a neutron.
What causes a splitting nucleus?
The capture of a neutron can split a nucleus - but only for certain isotopes like U-235 and Pu-239. Two naturally occurring isotopes undergo spontaneous fission, meaning the nucleus splits without neutron capture. These are 235U and 238U. A few other isotopes undergo spontaneous fission, but these are produced by an earlier neutron capture. Spontaneous fission is the result of quantum tunnelling, which is rather difficult to explain. There are related links below.
Why U 235 is fissioned by thermal neutron while U 238 by a fast neutron?
It's to do with the capture cross-section of the nucleus. It just happens that the U-235 nucleus has a much larger cross-section for neutron capture when the neutrons are slow, and that the subsequent nucleus is unstable and splits into two parts. With U-238, it does not undergo fission at all, it just absorbs the fast neutron and transmutes to Pu-239. As to the fundamental reason for this, it is in the complex nuclear physics field of study
Do radioactive elements emit radiation all the time?
In order for an atom of an element that is not radioactive to become radioactive, the isotope has to change. This can happen as a result of neutron capture. Neutron capture can simply change the isotope of an atom, as when cobalt-59, which is not radioactive, captures a neutron to become cobalt-60, which is radioactive. Neutron capture can also result in immediate radioactive decay of the atom struck, even if it is not radioactive. For example helium-3 can capture a neutron to produce two atoms of hydrogen, one of hydrogen-3 and one of hydrogen-1.
Is the parent isotope always radioactive In a nuclear equation?
No, the parent in the nuclear equation is not always radioactive. For example, the following reaction shows a neutron capture by 23Na, which is not radioactive. 1123Na + 01n --> 1124Na where 01n is a neutron.
What does xenon 135 decay into?
Xenon-135 decay to caesium-135 by beta emission.
What heappens to an atom that experiences radioactive decay?
Electron capture is the absorption of an electron by an atomic nucleus if that nucleus is neutron poor. An electron is captured, usually from an inner electron shell of that atom, and it will convert a proton in the nucleus into a neutron. We know that a neutron is converted into a proton and an electron in neutron decay, so it might be looked at as something of an opposite nuclear reaction where a proton and an electron combine to form a neutron.
What are the control rods in nuclear reactors made of?
Control rods are made of high neutron capture materials (e.g, Boron, Cadmium, and Gadolinium)
Why are smaller nuclei such as carbon-14 often radioactive?
Objection - assumes facts not in evidence.Okay, 14C actually is radioactive, but the even lower mass 13C and 12C are not. So it has nothing to do with being "smaller".It's possible that by "smaller" you're referring to the neutron capture cross section: I doubt it, but it's possible. If so, then you should realize that what you're asking is basically "Why is something that's unlikely to capture a neutron (because it already has so many that it's actively trying to get rid of one) unlikely to capture a neutron (i.e. has a low neutron capture cross section)".
