Differential cross-section and scattering.

[hhhmortal]

Homework Statement

A beam of 0.38 MeV neutrons is incident on a 113Cd foil of thickness 1mm. The absorption
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cross-section for 0.38 MeV neutrons is 5 barns. What is the fraction of neutrons absorbed by the foil?

The Attempt at a Solution

I'm not sure whether I should treat this as scattering in a thick or thin foil and how the energy of the incoming particles is related to the total scattering of particles.


Thanks.

 

[Rajini]

Hi, try this link. should be helpful.
http://hyperphysics.phy-astr.gsu.edu/hbase/nuclear/crosec2.html#c1

 

[hhhmortal]

Hi, try this link. should be helpful.
http://hyperphysics.phy-astr.gsu.edu/hbase/nuclear/crosec2.html#c1

Hi! I tried using the formulae given in that webpage. Problem is I don't know where the kinetic energy of the neutron (0.38 MeV) comes in into that equation. Anyhow I still get the wrong answer..

 

[Rajini]

Hi! I tried using the formulae given in that webpage. Problem is I don't know where the kinetic energy of the neutron (0.38 MeV) comes in into that equation. Anyhow I still get the wrong answer..

Just post your calculation. People will help you.

 

[hhhmortal]

For scattering in a thin foil:

R = F σ n A dx

We have to find R/F and then to get fraction of neutrons absorbed by foil (1 - R/F)

We know what σ, n and dx are, but not A. I don't know why they give me the energy value of the neutrons...?

 

[Rajini]

Please write what is n, A , etc..because many people use their own convention so better to write the key. Is A the mass number of target. ?
Did you miss anything in your question?
Okay i just made a simple calculation using the formula found in that website..
is your solution, i.e the fraction of neutron beam scattered is 0.023? (1-0.23)=0.977.
In fact i am sorry i also don't know why they have given the energy of beam.

 

[hhhmortal]

Please write what is n, A , etc..because many people use their own convention so better to write the key. Is A the mass number of target. ?
Did you miss anything in your question?
Okay i just made a simple calculation using the formula found in that website..
is your solution, i.e the fraction of neutron beam scattered is 0.023? (1-0.23)=0.977.
In fact i am sorry i also don't know why they have given the energy of beam.

Sorry forgot about that.

F = flux incident on target. (particles per m² per sec)

A = Total area of foil

n = number density of target atoms
σ = scattering cross section
dx = thickness of foil

Im having the exact same problem, I still can't figure it out.


Thanks.