Science Memes

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penetration tests (mander.xyz)

submitted 3 months ago by [email protected] to c/[email protected]

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[–] [email protected] 16 points 3 months ago (4 children)

idiot here. can someone explain to me how come neutrons can't penetrate concrete compared to lead.

[–] [email protected] 3 points 2 months ago* (last edited 2 months ago)

If you throw a ball at a brick wall it will bounce. If you throw a ball into a ball pit it will be slowed down and stop

[–] [email protected] 11 points 2 months ago

Neutrons need something that provides them with lots of chances to have interactions. Water is good too. What blocks neutrons may not block gamma and vise versa. To block neutrons and high energy particles like cosmic rays that actually have mass to them you need something like a crash barrier.

[–] [email protected] 4 points 3 months ago (2 children)

Same. Aren't neutrons capable of crossing the entire planet unless they directly colide with another particle?

[–] [email protected] 29 points 3 months ago

I reckon you're thinking of the neutrino which rarely interacts with matter.

[–] [email protected] 14 points 3 months ago* (last edited 3 months ago) (2 children)

I believe you're thinking of neutrinos. Neutrons love bonking into things, and they're really good at it. Too good; if the thing they're bonking is too big they'll just keep on bouncing, so you gotta bounce them off small stuff. Concrete has lots of small stuff bound up in it, so while there's better shields (borax and paraffin slurry is a classic one) there's few cheaper or easier to make shields than concrete.

[–] [email protected] 4 points 3 months ago

Neutrons are just so bonked up

[–] [email protected] 4 points 3 months ago

Oh oops. I did mix them up.

[–] [email protected] 19 points 3 months ago (1 children)

Another idiot here who found this answer interesting: https://www.quora.com/Why-is-concrete-the-best-shield-for-neutrons

[–] [email protected] 6 points 3 months ago

that's very interesting, thanks.