Alpha ray scattering experiment

[ananthu]

I have some basic doubts in the alpha ray scattering experiment by Rutherford and his students way back in 1909.

1.In the formula for the distance of the closest approach, the term velocity of the alpha particle and the charge of the gold nucleus appears. How did they measure the velocity of the alpha particle?

2. How did they know that the charge on the gold nucleus was 79? In 1909 were they aware of the atomic number of gold? If yes, by what means?

3. The alpha particles with different velocities will come to stop at different distances in front of gold foil. Then how did they know the exact radius of the gold nucleus?

Though there are some attempts to answer these questions in certain textbooks they are too complex to understand.

 

[10me]

As this is my first post, not sure if I should have started a new thread, but I also want to know,

Also, I understand that this offers a model of the atom as we have today of a dense nucleus and a relatively high volume of nonmatter, and that further experiments and discoveries probably served to strengthen this model as opposed to Thompson's plum pudding model. Could someone please provide references of such strengthening so that I may better understand its applicability?

For example, from my common macro-level experience, I can imagine an alternative deduction from the experiment as a pool ball collision in billiards. The movement of the white ball (analogous to the alpha particle) after hitting another pool ball (analogous to the gold atom) is dependent on what kind of spin you hit the white ball with. Therefore, why couldn’t the decay of the radon be such that the scattering of the alpha particle is dependent upon the random (in being uncontrolled and immeasurable) spin in which it leaves from the radioactive source. Such a possibility seems to uphold Thompson's model as possible.
"Bob_for_short" posted at the end of another thread, that there is "a strong Z- and M_a dependence." Assuming this is true, then the Thompson model seems less attractive to me unless maybe some type of nuclear interaction occurs between the gold atom and the alpha particle relative to the nuclear spin of the gold atom, which also is a factor in the degree of scattering of the alpha particle. From my knowledge, this can be consistent with the fact that the degree of scattering has a strong dependence on Z- and M_a (which I assume to be the atomic number and atomic mass, right?) as that nuclear spin may in turn be effected by these variables.

I do recognize I am going out of my way to find an alternative explanation, and again I would be glad to go through references that would strengthen the divergence of the theory of matter as phenomenalized by this experiment's deductions.

References that reveal falsifiability criteria of atomic level modeling (even currently) are also appreciated.