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Estimating the nuclear radius through alpha scattering watch

1. so why is it exactly that estimating accurately the radius of the nucleus is not possible? Why is it that you only get a bigger estimate than what the radius actually is? I thought you cant estimate it accurately because because the alpha particle gets taken over by the strong force and absorbed by the nucleus (given that the a particle has enough energy to get that close to the nucleus) before reaching the actual nucleus it self?

I'm making some revision so I would like to know why that is.
2. (Original post by Zevo)
so why is it exactly that estimating accurately the radius of the nucleus is not possible? Why is it that you only get a bigger estimate than what the radius actually is? I thought you cant estimate it accurately because because the alpha particle gets taken over by the strong force and absorbed by the nucleus (given that the a particle has enough energy to get that close to the nucleus) before reaching the actual nucleus it self?

I'm making some revision so I would like to know why that is.

What do you mean by "accurately"? That is a very important word in measurements. What do you mean by "actually is"?
A nucleus isn't some sort of small tennis ball where you can put a ruler across it and measure its "actual" diameter. Its "edge" is not that determinate. I'm talking fuzziness.

The alpha particles used in the original experiment did not have enough energy to fuse with the gold nucleus. They were all deflected by greater or lesser amounts, so forget this idea of the strong force having a significant influence. The force in action is the coulomb repulsion. Rutherford's calculations assumed the inverse square law of repulsion.
If you have a narrow beam of alpha particles being fired at a small nucleus, the pattern of the deflected particles (the numbers deflected through various angles) gives an estimate of the size of the nucleus. The maths is complicated. Rutherford did the maths and predicted what would happen. From the measured deflections and applying his formula, it was possible to get an estimate of the upper limit of the size of the nucleus. As this size turned out to be about 10-15m compared with the size of the atom being 10-10m this is a highly significant result.

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