# Neutron Shielding

Tags:
1. Feb 1, 2016

Suppose a shield that is infinite in the y and z directions and of thickness 1 meter in the x direction is constructed of alternating layers of materials A and B. Will this shield attenuate a beam of neutrons with more or less or the same attenuation that it would if it were constructed of the same amount of the two materials, but mixed homogeneously? Prove your choice.

Relevant equation: I(x) = I0exp(-N*σ*x)
where I is intensity, N is the number density, and σ is the cross section.

I believe that it would be better to alternate the two pure materials. My thought process is that this way the beam ensures going through regions of just A and B. This way, if material A is better at attenuating the beam, it will ensure interactions with A. I'm hoping someone can validate my thought process or possibly give an alternate reasoning. Thank you in advance!

2. Feb 1, 2016

### Staff: Mentor

You will always have interactions with A.
Instead of arguing with words, you can use the formula to get the result.

3. Feb 1, 2016

What exactly do you mean just use the formula?

4. Feb 2, 2016

### Staff: Mentor

That.

You can imagine alternating slices of A and B that get thinner and thinner and take the limit for 0 thickness.