Editing C. F. Powell (section)

== Professional life ==
In 1928 he took up a post as research assistant to [[Arthur Mannering Tyndall]] in the H.H. Wills Physical Laboratory at the [[University of Bristol]], later being appointed lecturer, and in 1948 appointed Melville Wills Professor of Physics.<ref>{{cite web |title=Nobel Prizes and Fellowships |url=http://www.bristol.ac.uk/university/distinctions/ |work=bristol.ac.uk |access-date=14 September 2009}}</ref> In 1936 he took part in a [[Royal Society]] expedition to [[Montserrat]] in the [[West Indies]] as part of a study of a damaging earthquake swarm.<ref>{{cite journal | doi=10.1098/rsta.1938.0002 | title=The Royal Society expedition to Montserrat, B.W.I. Final report | journal=Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences | year=1938 | volume=237 | issue=771 | pages=1–34 | bibcode=1938RSPTA.237....1P | last1=Powell | first1=C. F. | doi-access=free }}</ref> He appears on a stamp issued in [[Grenada]].<ref>{{cite web |title=Cecil Powell |url=http://th.physik.uni-frankfurt.de/~jr/gif/stamps/sm_powell.jpg |work=Goethe-Universität Frankfurt |publisher=Johann Wolfgang Goethe-Universität Frankfurt am Main |access-date=14 September 2009 |archive-url=https://web.archive.org/web/20090327010507/http://th.physik.uni-frankfurt.de/~jr/gif/stamps/sm_powell.jpg |archive-date=27 March 2009 |url-status=dead}}</ref>

During his time at Bristol University, Powell applied himself to the development of techniques for measuring the mobility of positive ions, to establishing the nature of the ions in common gases, and to the construction and use of a [[Cockcroft-Walton generator|Cockcroft generator]] to study the scattering of [[atomic nucleus|atomic nuclei]].<ref name=NobelBiog/> He also began to develop methods employing specialised [[Nuclear emulsion|photographic emulsions]] to facilitate the recording of the tracks of elementary particles, and in 1938 began applying this technique to the study of cosmic radiation,<ref name=NobelBiog/> exposing photographic plates at high-altitude, at the tops of mountains and using specially designed balloons,<ref>{{cite encyclopedia |year=1962 |title=Powell, Cecil |encyclopedia=Encyclopædia Britannica |publisher=Encyclopædia Britannica Limited |location=London }}</ref> collaborating in the study with [[Giuseppe Occhialini|Giuseppe "Beppo" Occhialini]], [[Hugh Muirhead]] and young Brazilian physicist [[César Lattes]]. This work led in 1947 to the discovery of the [[pion]] (pi-[[meson]]),<ref>{{cite web |title=The Nobel Prize in Physics 1901-2000 |url=http://nobelprize.org/nobel_prizes/physics/articles/karlsson/index.html |date=9 February 2000 |work=nobelprize.org |access-date=14 September 2009}}</ref> which proved to be the hypothetical particle proposed in 1935 by [[Hideki Yukawa]] in his theory of nuclear physics.<ref>{{Cite journal | last1 = Lattes | first1 = C. M. G. | last2 = Muirhead | first2 = H. | last3 = Occhialini | first3 = G. P. S. | last4 = Powell | first4 = C. F. | title = Processes Involving Charged Mesons | doi = 10.1038/159694a0 | journal = Nature | volume = 159 | issue = 4047 | pages = 694 | year = 1947 |bibcode = 1947Natur.159..694L | s2cid = 4152828 }}</ref>

In 1949 Powell was elected a Fellow of the Royal Society<ref name="frs"/><ref>{{cite web|title=List of Fellows of the Royal Society 1660–2007: K-Z |url=http://royalsociety.org/downloaddoc.asp?id=4275 |work=royalsociety.org |access-date=14 September 2009 |url-status=dead |archive-url=https://web.archive.org/web/20080609050913/http://royalsociety.org/downloaddoc.asp?id=4275 |archive-date=9 June 2008 }}</ref> and received the society's [[Hughes Medal]] the same year.<ref name=NobelBiog/> In 1950 he was awarded the [[Nobel Prize for Physics]] "for his development of the photographic method of studying nuclear processes and his discoveries regarding mesons made with this method". [[César Lattes]] was working with him at the time of the discovery and had improved the sensitivity of the photographic emulsion. [[César Lattes]] was the first to write an article describing the discovery that would lead to the Nobel Prize.<ref>{{cite web |title=The Nobel Prize in Physics 1950 |url=http://nobelprize.org/nobel_prizes/physics/laureates/1950/index.html |work=nobelprize.org/ |access-date=14 September 2009}}</ref> Debendra Mohan Bose (nephew of [[Jagadish Chandra Bose]]) and Chowdhuri published three consecutive papers in ''Nature'', but could not continue further investigation on account of "non-availability of more sensitive emulsion plates during the war years. Seven years after this discovery of mesons by DM Bose and Bibha Chowdhuri, C.F. Powell made the same discovery of pions and muons and further decay of muons to electrons… using the same technique". He acknowledged in his book, "In 1941, Bose and Chaudhuri (sic) had pointed it out that it is possible, in principle, to distinguish between the tracks of protons and mesons in an emulsion… They concluded that many of the charged particles arrested in their plates were lighter than protons, their mean mass being … the physical basis of their method was correct and their work represents the first approach to the scattering method of determining momenta of charged particles by observation of their tracks in emulsion". In fact, the measured mass of the particle by Bose and Chowdhuri was very close to the accepted value measured by Powell who used improved "full-tone" plates.<ref>{{Cite web|url=https://www.thestatesman.com/supplements/8thday/a-forgotten-legend-1502688129.html|title=A forgotten legend|date=2018-09-23|website=The Statesman|language=en-US|access-date=2019-12-18}}</ref> From 1952 Powell was appointed director of several expeditions to Sardinia and the Po Valley, Italy, utilizing high-altitude balloon flights.<ref name=NobelBiog/>

In 1955, Powell, also a member of the World Federation of Scientific Workers,<ref name=Pugwash1>{{cite web |title=The First Pugwash Conference |url=http://www.pugwash.org/about/conference.htm |work=pugwash.org |access-date=14 September 2009}}</ref> added his signature to the [[Russell-Einstein Manifesto]] put forward by Bertrand Russell, Albert Einstein and scientist [[Joseph Rotblat]], and was involved in preparations for the first [[Pugwash Conferences on Science and World Affairs|Pugwash Conference on Science and World Affairs]].<ref name=Pugwash1/> As Rotblat put it, "Cecil Powell has been the backbone of the Pugwash Movement. He gave it coherence, endurance and vitality." Powell chaired the meetings of the Pugwash Continuing Committee, often standing in for Bertrand Russell, and attended meetings until 1968.<ref>{{cite web |title=The Origins of the Russell-Einstein Manifesto by Sandra Ionno Butcher |url=http://www.pugwash.org/publication/phs/history9.pdf |date=May 2005 |work=Pugwash History Series |publisher=Council of the Pugwash Conferences on Science and World Affairs |access-date=14 September 2009 |archive-date=14 January 2013 |archive-url=https://web.archive.org/web/20130114141507/http://www.pugwash.org/publication/phs/history9.pdf |url-status=dead }}</ref>

In 1961 Powell received the [[Royal Medal]], and served on the Scientific Policy Committee of the European Organization for Nuclear Research ([[CERN]]) that year,<ref name=NobelBiog/> and in 1967 he was awarded the [[Lomonosov Gold Medal]] by the Academy of Sciences of the USSR (now Russian Academy of Sciences) "for outstanding achievements in the physics of elementary particles".<ref>{{cite web |title=Award list |url=http://www.ras.ru/win/db/award_dsc.asp?H=award_dsc&P=id-1.ln-en& |work=ras.ru |access-date=14 September 2009}}</ref>