What neutron energy regime is dominant with neutron capture?

In summary, the most dominant energy regime for neutron capture is thermal neutrons, with energies around 0.025 eV. While there may be some resonances at higher energies, the majority of neutrons are captured at thermal energies due to higher absorption cross sections.
  • #1
says
594
12
When a target is irradiated with neutrons there a number of different nuclear reactions that can occur. In neutron capture, which neutron energy regime is most dominant? I can't seem to find any specific literature about neutron capture and neutron energy, but most of the general stuff I've read leads me to believe the most dominant would be thermal neutrons.

Fast: >0.5 MeV.
Intermediate: 1 keV to 500 keV.
Resonance: 1 eV 1000 eV.
Epithermal: 0.025 eV 0.2 eV.
Thermal: ~0.025 eV.
 
Physics news on Phys.org
  • #2
Typically you have some resonances with high absorption cross sections for specific energies, and apart from that the cross sections increase with decreasing energy, so most neutrons are captured as thermal neutrons.
 

1. What is neutron capture and why is it important in nuclear reactions?

Neutron capture is a nuclear reaction in which a neutron is absorbed by an atomic nucleus, resulting in the formation of a new, heavier nucleus and often the release of energy. It is important in nuclear reactions because it can lead to the creation of new elements and isotopes, and is a key process in nuclear power production and nuclear weapon development.

2. What is the dominant neutron energy regime in neutron capture?

The dominant neutron energy regime in neutron capture is dependent on the type of target material being used. In general, for elements with low atomic numbers (up to about Z = 20), the dominant regime is thermal energy (energies of less than 1 eV). For heavier elements, the dominant regime is fast energy (energies of tens to hundreds of keV).

3. How does the neutron energy regime affect the outcome of a neutron capture reaction?

The neutron energy regime has a significant impact on the outcome of a neutron capture reaction. In thermal energy regimes, the probability of neutron capture is higher, resulting in a higher rate of reaction and higher production of heavy isotopes. In fast energy regimes, the probability of neutron capture is lower, but the energy of the captured neutron can lead to the creation of highly energetic and unstable nuclei, which can undergo further reactions.

4. What techniques are used to study neutron capture reactions in different energy regimes?

Various experimental techniques are used to study neutron capture reactions in different energy regimes. This includes using neutron sources with different energy spectra, such as thermal or fast neutron sources, and using detectors to measure the energy and type of particles emitted during the reaction. Theoretical modeling and simulations are also used to understand the behavior of neutron capture in different energy regimes.

5. How do neutron capture reactions contribute to our understanding of nuclear physics and astrophysics?

Neutron capture reactions play a crucial role in our understanding of nuclear physics and astrophysics. They help us to study the properties and behavior of nuclei, including their stability, and to test nuclear models. In astrophysics, neutron capture reactions are essential for the formation of heavy elements in stars and the universe, and for understanding the processes involved in stellar evolution and nucleosynthesis.

Similar threads

I Nucleus energy levels, neutron energy
    • High Energy, Nuclear, Particle Physics
Replies
15
Views
2K
I 7Li(p,e+e−)8Be direct proton-capture reaction X17
    • High Energy, Nuclear, Particle Physics
Replies
7
Views
1K
I Fission of 238U with high energy neutrons & other questions
    • High Energy, Nuclear, Particle Physics
Replies
12
Views
2K
Why do different nuclei need different neutron speed for neutron capture?
    • High Energy, Nuclear, Particle Physics
Replies
5
Views
5K
What are the rate equations for neutron capture on unstable nuclei B?
    • Advanced Physics Homework Help
Replies
1
Views
937
Neutron Capture Cross Section Dependence on Target Material Temperature
    • High Energy, Nuclear, Particle Physics
Replies
6
Views
6K
Why beryllium for neutron multiplication
    • High Energy, Nuclear, Particle Physics
Replies
6
Views
6K
Nuclear Chain Reaction Conditions
    • Nuclear Engineering
Replies
6
Views
2K
I Gamma absorption at increasing energy levels
    • High Energy, Nuclear, Particle Physics
Replies
5
Views
1K
I Gamma radiation, photon energies and wavelength question
    • High Energy, Nuclear, Particle Physics
Replies
4
Views
1K

Hot Threads

Recent Insights

Back
Top