Why prompt neutron gets less share of energy (fission)

In summary, the formula Em=Ef(M)/(m+M) only applies to decays to two particles. In fission reactions, the nucleus splits into two (or rarely three) parts, which then emit neutrons. The decay energies in these processes are a few MeV, which is the energy of the prompt neutrons. It is unclear if all neutrons are emitted simultaneously, as the definition of when the fission process is complete is ambiguous due to the nature of particles at the nuclear level.
  • #1
Magnetic Boy
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why neutron get so little energy in fission reaction as compare to fission fragments?
according to formula
Em=Ef(M)/(m+M)
m=mass of small fragment
M= mass of relatively big fragment
Ef=fission energy
by the same logic neutron should get highest share due to their lower mass. i am missing something please point out. thanks
 
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  • #2
That formula only works for decays to two particles. Fission splits the nucleus in two (rarely three) parts, those parts then emit neutrons. The decay energies of those processes are a few MeV - the energy of the prompt neutrons (to a good approximation).
 
  • #3
mfb said:
That formula only works for decays to two particles. Fission splits the nucleus in two (rarely three) parts, those parts then emit neutrons. The decay energies of those processes are a few MeV - the energy of the prompt neutrons (to a good approximation).
are neutrons emit with fission simulatneously?
 
  • #4
Some are clearly emitted later, for some the question becomes ambiguous - how long do you consider neutrons part of a nucleus, and when exactly is the fission process done? You don't have classical objects moving around.
 

1. Why does prompt neutron receive less energy in fission compared to delayed neutron?

The distribution of energy in fission is determined by the type of nuclei undergoing the process. In most cases, the nuclei involved in fission have a higher chance of producing delayed neutrons, which means that the prompt neutrons receive less energy. This is due to the energy being shared among all the particles produced during the fission process.

2. How does the energy distribution between prompt and delayed neutron affect the stability of the fission process?

The energy distribution between prompt and delayed neutron has a significant impact on the stability of the fission process. If prompt neutrons receive too much energy, it can lead to an uncontrollable chain reaction, which is dangerous. On the other hand, if delayed neutrons receive more energy, it can slow down the fission process, making it less efficient.

3. Is there a way to control the energy distribution between prompt and delayed neutron in fission?

Yes, the energy distribution between prompt and delayed neutron can be controlled by adjusting the conditions of the fission process. For example, the type of nuclei used, the amount of fuel, and the presence of moderators can all affect the energy distribution between prompt and delayed neutron.

4. Why is it important to have a balance between prompt and delayed neutron energy in fission?

A balance between prompt and delayed neutron energy is essential for the stability and efficiency of the fission process. If there is too much energy given to prompt neutrons, it can lead to an uncontrolled chain reaction, which can be dangerous. On the other hand, if delayed neutrons receive too much energy, it can slow down the fission process, making it less efficient.

5. Can the energy distribution between prompt and delayed neutron be altered artificially?

Yes, the energy distribution between prompt and delayed neutron can be altered artificially by using different types of nuclear fuels, such as enriched uranium or plutonium, or by using moderators or control rods to regulate the fission process. However, this requires careful planning and control to maintain a safe and efficient fission reaction.

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