# Where is the experimental data of Rutherford Gold Foil Experiments?

Is there quantitive data or equations matching the experimental data that can logically support Rutherfords model that there is a high mass dense nucleus? The only data i heard of was that one in 20000 alpha particles rebounded, but this is not published and their doesnt seem to be other results. There does not seem to be any results or data from the original experiment published, or any new trials of the experiment? I have also seen in places that their data was possibly made or fabricated to find better relationships. this could have been done since the experiement was not very accurate. is this true?

I just cant support his model if their is no evidence, and i was wondering if (and even where) is the evidence?

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Time line according to publications

• 1906 Rutherford publishes an article (Philosophical Magazine, volume 12, 134 (1906)) presenting the results of $\alpha$-particle penetration through a variety of materials.
• 1908 Geiger (working for Rutherford) publishes an article Proc. Roy. Soc. A, lxxxi,174 (1908) in which he notices "some of the $\alpha$-particles after passing through the very thin leaves ... were deflected through quite an appreciable angle."
• 1909 Geiger and Marsden publish a paper (Proc. Roy. Soc.,lxxxii,495 (1909) ) on the deflection of $\alpha$-particles from various materials. They also note that there is a small fraction (1/8000) of particles reflected back on the same side as incident particles. Rutherford thought these results to be conflicting with Thomson's model.
• 1910 Geiger publishes a paper (Proc. Roy. Soc., lxxxiii, 492 (1910)) with a detailed study of the average scattering angle and most probable scattering angle of $\alpha$-particles from a variety of substances.
• 1911 Prompted by Geiger and Marsden's work so far, Rutherford proposes the nuclear model with predictions of scattering cross-sections (Philosophical Magazine, Series 6, vol. 21, 669 (1911)). Geiger and Marsden's definitive experiment had NOT been published yet. This was a theoretical paper.
• 1913 Geiger and Marsden publish the results of a detailed experiment demonstrating consistency with Rutherford's 1911 predictions. This is where the data is: Philosophical Magazine, Series 6, Vol. 25, 604 (1913)
• Don't forget the 1908 paper ("On the Scattering of $\alpha$-Particles by Matter"). That any $\alpha$ particles were backscattered was unexpected, much less the number that were observed. This immediately indicated that a different model was needed. Further, it should be remembered that Geiger and Marsden were working under Rutherford in his lab, so Rutherford had, shall we say, easy access to the on-going results from the experiments. – Jon Custer Oct 26 '17 at 19:46
• @JonCuster Right. I read one history (can't remember which one) that actually speculated Rutherford already had good backscatter data from G&M, but delayed their publication while he put forth the 1911 paper. I'm not sure about that, but it's an interesting speculation about how scientists build on their reputation. I'll edit to include the links to the Ruterford 1906 and Geiger 1908 papers.. – Bill N Oct 27 '17 at 20:34

I don't know where Rutherford put his notes but I can dig you out my old lab book from 1981 when I did it as part of a Physics degree. It is quite a meaty experiment for a third-year student - you get to work with a real live radioactive source and the mathematical analysis of the results is quite challenging (you will find a $cosec^4({\theta\over{2}})$ dependency).

It's worth recalling why this experiment caused such a stir at the time. In the early 1900s, the prevailing model of the atom was the Plum Pudding Model, in which the negative electrons were embedded in a continuous matrix of positive charge (like plums in a pudding). If this were true, a large, heavy, $\alpha$-particle should just plough through in a mostly straight line, with only a few minor deviations from interactions with electrons. That it could wander round in a semi-circle and come back out the way it went in was unthinkable. Rutherford's genius was in realising that the only way that could happen, was if the $\alpha$-particle had hit something larger and heavier than itself - an atomic nucleus.

• Hey thanks for the answer! That will be absoloutely awesome if i could have a look at that! Wow, let me know how i can have a look – Jr. Mathematician Oct 25 '17 at 10:52
• @Jr.Mathematician Perhaps I was mistaken, but I read into your original question a certain pathological skepticism - as if you found it all a bit hard to believe. As others have noted above, there are many write-ups of this experiment and it is a standard component of a degree-level course in Nuclear Physics, so millions of students have done it. There really is no doubt about its veracity. However, since I did offer (albeit tongue-in-cheek), I'll crawl into the cellar and see if I can find it. – Oscar Bravo Oct 26 '17 at 7:39
• :)) oarms1@icloud.com if you do end up finding anything useful and willing to share. Up to you! Kind Regards – Jr. Mathematician Oct 26 '17 at 17:01