About neutrons, theyve been bothering me

Hey guys, posted this in HW help, but its actually just a thought i had in chem class.
I was wondering if light or heavy elements would be better at stopping slow moving neutrons? And how come? By heavy and light, i mean mass.

Heres what i think. I thought a heavy element would have a better chance of stopping particles because they have a high probability of smacking the heavy elements' nucleus, but does this apply to neutrons flying through other heavy elements? Kinda like Rutherford's experiment eh?

Thanks guys. :wink:


Science Advisor
You have to more specific about "stopping". Neutrons can be absorbed or scattered when interacting with nuclei (there are also other possibilites, but I won't go into them). Absorption depends on the particular nucleus involved. For example boron is a very good absorber and is used to stop nuclear reactors when necessary. Scattering will gnerally slow neutrons down, although at some point the neutrons will be at the same temperature as the medium (that's why these are called thermal) and will continue at the same speed on average. Finally faster neutrons are slowed down fastest by light elements - that is why water (hydrogen) is the moderator for most reactors.

thanks man. So i guess my thought was slightly off, considering i didnt think about absorbtion or scattering. Thanks again man. Finally the crazy thought i had in class is quenched. In fact i think ill look up the other ways that a neutron could be stopped also, they seem interesting.

Thank you once again for providing me with insight. :wink:

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