Low energy neutrons are more likely to cause U235 fission because they have a higher probability of interacting with the nucleus of the U235 atom. This is because the energy of the neutron is directly related to its velocity, and at low energies, the neutron moves slower and has a higher chance of being captured by the U235 nucleus.
The size of the U235 nucleus plays a crucial role in its likelihood of fission. U235 has a larger nucleus compared to other fissile materials, which means it has a higher probability of capturing a low energy neutron. This increases the chances of inducing fission in the U235 nucleus.
Yes, high energy neutrons can also cause U235 fission. However, the probability of fission decreases as the energy of the neutron increases. This is because at higher energies, the neutron moves faster and has a lower chance of being captured by the U235 nucleus. Therefore, lower energy neutrons are more efficient at inducing fission in U235.
The fission cross section of U235 is the measure of the probability of fission occurring when a neutron interacts with the nucleus. This cross section increases with lower energy neutrons and reaches a peak at thermal (low) energies. As the neutron energy increases, the fission cross section decreases, showing that low energy neutrons are more likely to cause fission in U235.
Apart from neutron energy, the likelihood of U235 fission can also be influenced by the concentration of U235 in the nuclear material, the density of the material, and the presence of other nuclei that can absorb neutrons. Additionally, the shape and size of the material can also affect the probability of fission as it can alter the likelihood of neutron capture by the U235 nucleus.