Developing a value for ∑f depends on the atomic density, which depends on the form, e.g., elemental, alloy or ceramic. What form is one considering? The value of ν depends on neutron energy, and in a thermal spectrum, it will depend on U-235.Kirk Truax said:
Yeah, but that's for fast neutrons. Fast neutrons from fission have a peak distribution around 1 MeV and the energy distribution falls off rapidly up to 10 MeV. With d+t fusion, one gets up to 14.1 MeV neutrons. To go higher, one pretty much needs 20+ MeV protons and spallation reactions.jim hardy said:
Astronuc said:
Hey guys,Astronuc said:
Neutron fission cross section is a measure of the likelihood that a neutron will cause a nucleus to fission, or split into two or more smaller nuclei. It is an important quantity in nuclear physics and is used to calculate the rate of nuclear reactions.
Neutron fission cross section is typically measured using a particle accelerator or a reactor. In these experiments, a beam of neutrons is directed at a target nucleus, and the number of fission events is recorded. The ratio of fission events to the total number of neutrons in the beam gives the fission cross section.
The neutron fission cross section of a nucleus depends on several factors, including the energy of the neutron, the size and shape of the nucleus, and the presence of other particles, such as protons or neutrons, in the nucleus.
Neutron fission cross section is important for understanding and predicting nuclear reactions, such as those that occur in nuclear power plants and nuclear weapons. It also plays a role in the study of nuclear structure and the production of nuclear isotopes.
Neutron fission cross section is a crucial factor in determining whether a nuclear chain reaction can occur. If the fission cross section is above a certain threshold, then a chain reaction can be sustained. This is why nuclear reactors require a critical mass of fuel to maintain a chain reaction.