Editing Nuclear physics (section)

=== Rutherford discovers the nucleus ===
In 1906, [[Ernest Rutherford]] published "Retardation of the a Particle from Radium in passing through matter."<ref>{{cite journal|last=Rutherford|first=Ernest|author-link1=Ernest Rutherford|title=On the retardation of the α particle from radium in passing through matter|journal=[[Philosophical Magazine]]|year=1906|volume=12|number=68|pages=134–146|doi=10.1080/14786440609463525|url=https://zenodo.org/record/1430810|access-date=2019-07-01|archive-date=2022-03-31|archive-url=https://web.archive.org/web/20220331091115/https://zenodo.org/record/1430810|url-status=live}}</ref> [[Hans Geiger]] expanded on this work in a communication to the [[Royal Society]]<ref>{{cite journal|last=Geiger|first=Hans|author-link1=Hans Geiger|title=On the scattering of α-particles by matter|journal=[[Proceedings of the Royal Society A]]|year=1908|volume=81|number=546|pages=174–177|doi=10.1098/rspa.1908.0067 |bibcode=1908RSPSA..81..174G|doi-access=free}}</ref> with experiments he and Rutherford had done, passing alpha particles through air, aluminum foil and gold leaf. More work was published in 1909 by Geiger and [[Ernest Marsden]],<ref>{{cite journal | last1 =Geiger | first1 =Hans| author-link1=Hans Geiger|last2=Marsden|first2=Ernest|author-link2=Ernest Marsden| title=On the diffuse reflection of the α-particles | year =1909 | volume=82| pages =495|number=557|journal=[[Proceedings of the Royal Society A]] | doi=10.1098/rspa.1909.0054 |bibcode=1909RSPSA..82..495G| doi-access=free}}</ref> and [[Geiger–Marsden experiments|further greatly expanded work was published in 1910 by Geiger]].<ref>{{cite journal|last=Geiger|first=Hans|author-link1=Hans Geiger|title=The scattering of the α-particles by matter|year=1910|volume=83|number=565|pages=492–504|journal=[[Proceedings of the Royal Society A]]|doi=10.1098/rspa.1910.0038|bibcode=1910RSPSA..83..492G|doi-access=free}}</ref> In 1911–1912 Rutherford went before the Royal Society to explain the experiments and propound the new theory of the atomic nucleus as we now understand it.

Published in 1909,<ref>H. Geiger and E. Marsden, PM, 25, 604 1913, ''citing'', H. Geiger and E. Marsden, Roy. Soc. Proc. vol. LXXXII. p. 495 (1909), in,  [http://www.physics.utah.edu/~lebohec/P5110/Material/geiger_marsden_1913.pdf The Laws of Deflexion of α Particles Through Large Angles \\ H. Geiger and E. Marsden] {{Webarchive|url=https://web.archive.org/web/20190501022445/http://www.physics.utah.edu/~lebohec/P5110/Material/geiger_marsden_1913.pdf |date=2019-05-01 }} (1913), (published subsequently online by – physics.utah.edu ([[University of Utah]])) Retrieved June 13, 2021 (p.1):"..In an earlier paper, however, we pointed out that α particles are sometimes turned through very large angles..."(p.2):"..Professor Rutherford has recently developed a theory to account for the scattering of α particles through these large angles, the assumption being that the deflexions are the result of an intimate encounter of an α particle with a single atom of the matter traversed. In this theory an atom is supposed to consist of a strong positive or negative central charge concentrated within a sphere of less than about 3 × 10–12 cm. radius, and surrounded by electricity of the opposite sigh distributed throughout the remainder of the atom of about 10−8 cm. radius..."</ref> with the eventual classical analysis by Rutherford published May 1911,<ref name=Radvanyi>{{cite journal |last1=Radvanyi |first1=Pierre |date=January–February 2011 |title=Physics and Radioactivity after the Discovery of Polonium and Radium |url=http://publications.iupac.org/publications/ci/2011/3301/8_radvanyi.html |access-date=13 June 2021 |format=electronic |journal=Chemistry International |language=English |location=online |publisher=[[International Union of Pure and Applied Chemistry]] |publication-date=January–February 2011 |volume=33 |issue=1 |quote="..Geiger and an English-New Zealand student, E. Marsden, to study their scattering through thin metallic foils. In 1909, the two physicists observe that some alpha-particles are scattered backwards by thin platinum or gold foils (Geiger 1909)...It takes Rutherford one and a half years to understand this result. In 1911, he concludes that the atom contains a very small 'nucleus'..." |archive-date=9 July 2023 |archive-url=https://web.archive.org/web/20230709185302/http://publications.iupac.org/publications/ci/2011/3301/8_radvanyi.html |url-status=live }}</ref><ref>{{cite journal
| url = https://www.chemteam.info/Chem-History/Rutherford-1911/Rutherford-1911.html
| last1 = Rutherford F.R.S.
| first1 = E.
| title = The Scattering of α and β Particles by Matter and the Structure of the Atom
| date = May 1911
| journal = Philosophical Magazine
| series = 6
| volume = 21 May 1911
| pages = 669–688
| archive-url = https://web.archive.org/web/20200212052356/https://www.chemteam.info/Chem-History/Rutherford-1911/Rutherford-1911.html
| archive-date = 12 February 2020
| accessdate = 13 June 2021
| url-status = live
}}</ref><ref>{{cite journal |last1=Rutherford |first1=E. |title=LXXIX. The scattering of α and β particles by matter and the structure of the atom |journal=The London, Edinburgh, and Dublin Philosophical Magazine and Journal of Science |date=May 1911 |volume=21 |issue=125 |pages=669–688 |doi=10.1080/14786440508637080}}</ref><ref>{{cite web
| url = https://www.fnal.gov/pub/inquiring/timeline/03.html
| title = 1911 John Ratcliffe and Ernest Rutherford (smoking) at the Cavendish Laboratory...
| publisher = [[Fermilab]]
| archive-url = https://web.archive.org/web/20210401022934/https://www.fnal.gov/pub/inquiring/timeline/03.html
| archive-date = 1 April 2021
| accessdate = 13 June 2021
| url-status = live
}}"..that would become a classic technique of particle physics..."</ref> the key preemptive experiment was performed during 1909,<ref name=Radvanyi/><ref>*{{cite web 
|url=https://micro.magnet.fsu.edu/electromag/java/rutherford/ 
|last1=Davidson 
|first1=Michael W 
|department=micro.magnet. 
|website=micro.magnet.fsu.edu 
|publisher=[[Florida State University]] 
|title=The Rutherford Experiment 
|location=[[Florida State]] 
|access-date=13 June 2021 
|archive-url=https://web.archive.org/web/20210613142921/https://micro.magnet.fsu.edu/electromag/java/rutherford/ 
|archive-date=13 June 2021 
|url-status=live 
}} "experiment was conducted 1911"
*{{cite web
 |url          = https://cerncourier.com/a/rutherford-transmutation-and-the-proton/
 |title        = <small>CULTURE AND HISTORY FEATURE</small> Rutherford, transmutation and the proton 8 May 2019 The events leading to Ernest Rutherford's discovery of the proton, published in 1919.
 |work         = [[CERN Courier]]
 |date         = 8 May 2019
 |publisher    = [[IOP Publishing]]
 |archive-url  = https://web.archive.org/web/20210418113242/https://cerncourier.com/a/rutherford-transmutation-and-the-proton/
 |archive-date = 18 April 2021
 |accessdate   = 13 June 2021
 |url-status   = live
}}"...1909...a couple of years later..."
*{{cite journal
 |date         = May 2006
 |url          = https://www.aps.org/publications/apsnews/200605/history.cfm
 |title        = This Month in Physics History: May, 1911: Rutherford and the Discovery of the Atomic Nucleus
 |volume       = 15
 |issue        = 5
 |journal      = [[APS News]]
 |archive-url  = https://web.archive.org/web/20210613142920/https://www.aps.org/publications/apsnews/200605/history.cfm
 |archive-date = 13 June 2021
 |accessdate   = 13 June 2021
 |url-status   = live
}}"..1909..published – 1911.."
*{{cite web 
| url =http://ffden-2.phys.uaf.edu/212_spring2005.web.dir/ashley_anderson/atomic_timeline.html 
| author =Anderson, Ashley 
| title =Timeline 
| publisher =University of Alaska-Fairbanks 
| archive-url =https://web.archive.org/web/20210613142921/http://ffden-2.phys.uaf.edu/212_spring2005.web.dir/ashley_anderson/atomic_timeline.html 
| archive-date =13 June 2021 
| accessdate =13 June 2021 
| url-status =live 
}}  "1911 performed "
*1911 discovers:
**Leonard, P.  and Gehrels, N. (November 28, 2009) [https://heasarc.gsfc.nasa.gov/docs/history/ A History of Gamma-Ray Astronomy Including Related Discoveries] {{Webarchive|url=https://web.archive.org/web/20210613142921/https://heasarc.gsfc.nasa.gov/docs/history/ |date=2021-06-13 }} [[National Aeronautics and Space Administration]] [[Goddard Space Flight Center]]:  [[High Energy Astrophysics Science Archive Research Center]] (HEASARC), Retrieved 13 June 2021
**Rizvi, Eram – [http://pprc.qmul.ac.uk/~rizvi/Talks/Lecture1.pdf Quantum Mechanics and Particle Scattering Lecture 1] {{Webarchive|url=https://web.archive.org/web/20210613142922/http://pprc.qmul.ac.uk/~rizvi/Talks/Lecture1.pdf |date=2021-06-13 }}, p.9, pprc.qmul.ac.uk [[Queen Mary University London]]: School of Physics and Astronomy – Particle Physics Research Centre, Retrieved 13 June 2021 "..by Rutherford.."
*[https://www.nobelprize.org/prizes/chemistry/1908/rutherford/biographical/ rutherford/biographical] {{Webarchive|url=https://web.archive.org/web/20230603075847/https://www.nobelprize.org/prizes/chemistry/1908/rutherford/biographical/ |date=2023-06-03 }}, [[Nobel Prize]],  "..In 1910, his investigations into the scattering of alpha rays and the nature of the inner structure of the atom which caused such scattering led to the postulation of his concept of the 'nucleus'..."
*{{cite web
| url = https://spark.iop.org/collections/case-studies-history-physics
| title = Case studies from the history of physics
| publisher = [[Institute of Physics]]
| archive-url = https://web.archive.org/web/20210422133723/https://spark.iop.org/collections/case-studies-history-physics
| archive-date = 22 April 2021
| quote = "..It is suggested that, in 1910, the 'plum pudding model' was suddenly overturned by Rutherford's experiment. In fact, Rutherford had already formulated the nuclear model of the atom before the experiment was carried out.."
| accessdate = 13 June 2021
| url-status = live
}}</ref><ref name=Jariskog>{{cite web
| url = https://cds.cern.ch/record/1734171/files/vol48-issue10-p019-e.pdf
| title = <small>ANNIVERSARY</small> The nucleus and more
| last1 = Jariskog
| first1 = Cecilia
| date = December 2008
| magazine = [[CERN Courrier]]
| volume = 48
| issue = 10
| page = 21
| archive-url = https://web.archive.org/web/20210613142922/https://cds.cern.ch/record/1734171/files/vol48-issue10-p019-e.pdf
| archive-date = 13 June 2021
| quote = ".. in 1911, Rutherford writes: "I have been working recently on scattering of alpha and beta particles and have devised a new atom to explain the results.."
| accessdate = 13 June 2021
| url-status = live
}}</ref><ref name=Godenko>{{cite book |last1=Godenko |first1=Lyudmila |title=The Making of the Atomic Bomb |url=https://cuny.manifoldapp.org/read/he-making-of-the-atomic-bomb/section/21c33a72-ee12-4198-a0cd-0b618a14b5ff#topic-4-the-nuclear-atom-1911-1920.-alpha-scattering-and-the-discovery-of-the-nucleus.-nuclear-sizes-vs-atomic-sizes.-niels-bohr-and-the-structure-of-the-nuclear-atom.-moseleys-work-with-x-rays-and-the-significance-of-the-atomic-number. |format=E-Book |publisher=cuny.manifoldapp.org CUNY's Manifold ([[City University of New York]]) |archive-url= |archive-date= |access-date=13 June 2021 |quote="The discovery for which Rutherford is most famous is that atoms have nuclei; ...had its beginnings in 1909...Geiger and Marsden published their anomalous result in July, 1909...The first public announcement of this new model of atomic structure seems to have been made on March 7, 1911, when Rutherford addressed the Manchester Literary and Philosophical Society;..." }}{{Dead link|date=December 2023 |bot=InternetArchiveBot |fix-attempted=yes }}</ref> at the [[University of Manchester]]. Ernest Rutherford's assistant, Professor <ref name=Godenko/> Johannes <ref name=Jariskog/> "Hans" Geiger, and an undergraduate, Marsden,<ref name=Godenko/> performed an [[Geiger–Marsden experiment|experiment in which Geiger and Marsden]] under Rutherford's supervision fired alpha particles ([[Helium-4 nucleus|helium 4 nuclei]]<ref>{{cite web |last=Watkins |first=Thayer |title=The Structure and Binding Energy of the Alpha Particle, the Helium 4 Nucleus |access-date=14 June 2021 |url=https://www.sjsu.edu/faculty/watkins/He4.htm |publisher=[[San Jose University]] |archive-url=https://web.archive.org/web/20200130165819/http://www.sjsu.edu/faculty/watkins/He4.htm |archive-date=30 January 2020 |url-status=dead }}</ref>) at a thin film of [[gold]] foil. The [[plum pudding model]] had predicted that the alpha particles should come out of the foil with their trajectories being at most slightly bent. But Rutherford instructed his team to look for something that shocked him to observe: a few particles were scattered through large angles, even completely backwards in some cases. He likened it to firing a [[bullet]] at tissue paper and having it bounce off. The discovery, with Rutherford's analysis of the data in 1911, led to the Rutherford model of the atom, in which the atom had a very small, very dense [[Atomic nucleus|nucleus]] containing most of its mass, and consisting of heavy positively charged particles with embedded electrons in order to balance out the charge (since the neutron was unknown). As an example, in this model (which is not the modern one) nitrogen-14 consisted of a nucleus with 14 protons and 7 electrons (21 total particles) and the nucleus was surrounded by 7 more orbiting electrons.