Influence on Neutron spectrum due to energy loss of beam

In summary, the conversation discusses the impact of energy loss due to proton-target collisions on the neutron energy spectrum in a (p,n) reaction with 6Li or 7Li. The use of Bethe-Bloch equation is suggested to calculate the energy loss, but it is unclear if this will have any influence on the neutron energy spectrum since neutrons are not charged. The conversation also touches on the concept of nuclear reactions and the consequences of less energetic protons on the expected neutron energy. The importance of considering conservation of energy in nuclear reactions is emphasized and the use of a textbook is suggested for further understanding.
  • #1
andy95220
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Suppose some protons are impacted on a Lithium target to produce neutrons with energies close to the proton energy. If one considers Energy-loss due to proton-target collision (ionization of the target atoms), will this kind of energy loss influence neutron energy spectrum?

I am asked by my professor to calculate the energy loss of a proton beam with kinetic energy of 100MeV in a 28mm thick lithium target. I used Bethe-Bloch Eq to get the energy loss of the proton beam is about 3 MeV. But I have no idea whether this will have any influence on the spectrum of neutron.

I asked my professor today. He said we only need to consider Bethe-Bloch Eq to get the answer...Does anyone have any suggestion?
 
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  • #2
What determines the energy of a neutron produced from a (p,n) reaction with 6Li or 7Li?

Should there be a difference in neutron energy from a (p,n) reaction with a 97 MeV proton vs a 100 MeV proton?

Also, think of what the Bethe-Bloch equation represents. Are there other energy loss/transfer mechanisms?
 
  • #3
Astronuc said:
What determines the energy of a neutron produced from a (p,n) reaction with 6Li or 7Li?

Should there be a difference in neutron energy from a (p,n) reaction with a 97 MeV proton vs a 100 MeV proton?

Also, think of what the Bethe-Bloch equation represents. Are there other energy loss/transfer mechanisms?
I guess there is no influence on the neutron energy spectrum since the neutron is not charged...is this reasonable?
 
  • #4
andy95220 said:
I guess there is no influence on the neutron energy spectrum since the neutron is not charged...is this reasonable?
What neutron energy would one expect from a (p,n) reaction with 6Li and 7Li?
 
  • #5
Astronuc said:
What neutron energy would one expect from a (p,n) reaction with 6Li and 7Li?

One should expect the neutrons to have same energy of the protons. I don’t know much about nuclear reactions. Could you please explain more?
 
  • #6
andy95220 said:
One should expect the neutrons to have same energy of the protons. I don’t know much about nuclear reactions. Could you please explain more?
So, it appears that one has not done nuclear reactions yet. Therefore the emphasis on the question in the original power is the effect of slowing down protons and the consequence of the expected neutron energy. Getting back to that, what would one expect as the consequence of less energetic protons?

With respect to nuclear reactions, one has to consider the difference in masses of the incident particle (proton in this case) and target nucleus, and the masses of the resulting nucleus and neutron. One needs to determine the change in mass by taking the difference of the masses before the reaction and those after. If the change in mass is positive, the reaction is exoergic, i.e., there is excess energy available to the products. If the mass difference is negative, the reaction is endoergic, and there will need to be some energy input (e.g., kinetic energy) to make the reaction happen.
http://230nsc1.phy-astr.gsu.edu/hbase/Nuclear/nucrea.html
 
  • #7
Astronuc said:
So, it appears that one has not done nuclear reactions yet. Therefore the emphasis on the question in the original power is the effect of slowing down protons and the consequence of the expected neutron energy. Getting back to that, what would one expect as the consequence of less energetic protons?

With respect to nuclear reactions, one has to consider the difference in masses of the incident particle (proton in this case) and target nucleus, and the masses of the resulting nucleus and neutron. One needs to determine the change in mass by taking the difference of the masses before the reaction and those after. If the change in mass is positive, the reaction is exoergic, i.e., there is excess energy available to the products. If the mass difference is negative, the reaction is endoergic, and there will need to be some energy input (e.g., kinetic energy) to make the reaction happen.
http://230nsc1.phy-astr.gsu.edu/hbase/Nuclear/nucrea.html

Thank you for your comments! Yes you are right! But I don’t know what’s the consequences of less energetic protons, could you please give me more hints?
 
  • #8
andy95220 said:
But I don’t know what’s the consequences of less energetic protons, could you please give me more hints?
What does one know about conservation of energy in nuclear reactions?

What textbook is one using?
 
  • #9
You are almost there. You know the neutron energy from a 100 MeV proton (assuming you followed the previous hints). What will the neutron energy from a 97 MeV proton be compared to the previous case?
 

FAQ: Influence on Neutron spectrum due to energy loss of beam

Q: How does energy loss of a beam affect the neutron spectrum?

A: The energy loss of a beam can impact the neutron spectrum in various ways. When a beam loses energy, it can cause a shift in the neutron energy distribution, also known as the neutron spectrum. This can result in changes in the number and energy of neutrons, as well as the shape of the spectrum.

Q: What factors influence the neutron spectrum due to energy loss of a beam?

A: The neutron spectrum can be affected by several factors, such as the type and energy of the beam, the material it is passing through, and the distance it has traveled. Other factors that can influence the neutron spectrum include the scattering and absorption properties of the material, as well as any shielding or filtering used.

Q: How is the neutron spectrum measured and analyzed?

A: The neutron spectrum can be measured using various techniques, including neutron spectrometry and activation analysis. These methods involve detecting and measuring the energy and number of neutrons emitted from a material after being bombarded by the beam. The collected data is then analyzed using mathematical models and simulations to determine the characteristics of the neutron spectrum.

Q: What applications rely on understanding the influence of energy loss on neutron spectrum?

A: Understanding the influence of energy loss on neutron spectrum is crucial in many fields, including nuclear engineering, medical physics, and materials science. It is especially important in radiation therapy and nuclear power generation, where precise control and characterization of the neutron spectrum are necessary for safe and effective operations.

Q: How can the influence of energy loss on neutron spectrum be minimized or controlled?

A: There are various methods to minimize or control the influence of energy loss on neutron spectrum, such as using different materials or adjusting the energy and intensity of the beam. Shielding and filtering techniques can also be employed to modify the neutron spectrum. Additionally, precise measurements and simulations can help optimize the neutron spectrum for specific applications.

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