View source for C. F. Powell

{{Short description|British experimental physicist (1903–1969)}}
{{Use dmy dates|date=March 2020}}
{{Infobox scientist
| name              = Cecil Powell
| honorific_suffix  = {{Post-nominals|FRS|size=100%}}
| image             = Cecil Powell.jpg
| caption           = Powell in 1950
| birth_name        = Cecil Frank Powell
| birth_date        = {{Birth date|1903|12|05|df=yes}}
| birth_place       = [[Tonbridge]], [[England]], [[UKGBI]]
| death_date        = {{Death date and age|1969|08|09|1903|12|05|df=yes}}
| death_place       = [[Casargo]], [[Lombardy]], Italy
| education         = [[Judd School]]
| alma_mater        = {{Indented plainlist|
* [[Sidney Sussex College, Cambridge]] ([[Bachelor of Arts|BA]])
* [[University of Cambridge]] ([[PhD]])}}
| known_for         = Discovery of the [[pion]]
| spouse            = {{Marriage|Isobel Artner|1932}}
| children          = 2
| awards            = {{Indented plainlist|
* [[Hughes Medal]] (1949)
* [[Nobel Prize in Physics]] (1950)
* [[Royal Medal]] (1961)
* {{Nowrap|[[Lomonosov Gold Medal]] (1967)}}}}
| fields            = [[Particle physics]]
| work_institutions = [[University of Bristol]] (1927–1969)
| doctoral_advisors = {{Plain list|
* [[Ernest Rutherford]]
* [[C. T. R. Wilson]]}}
| notable_students  = {{Plain list|
* [[Peter Fowler (physicist)|Peter Fowler]]<ref name=PhysicsTree>{{Cite web|title=Cecil Frank Powell - Physics Tree|url=https://academictree.org/physics/peopleinfo.php?pid=93268|website=academictree.org|access-date=2025-08-10}}</ref>
* [[Michael W. Friedlander]]<ref name=PhysicsTree/>
* [[M. G. K. Menon]]<ref name=PhysicsTree/>
}}
}}

'''Cecil Frank Powell''' (5 December 1903 – 9 August 1969) was a British [[experimental physicist]] who received the [[Nobel Prize in Physics]] in 1950 for heading the team that developed the photographic method of studying nuclear processes, and for the resulting discovery of the [[pion]] (pi-[[meson]]).<ref name=Nobel1950>{{Cite web|title=The Nobel Prize in Physics 1950|url=https://www.nobelprize.org/prizes/physics/1950/summary/|url-status=live|publisher=[[Nobel Foundation]] |archive-url=https://web.archive.org/web/20081005100443/http://nobelprize.org/nobel_prizes/physics/laureates/1950/index.html|archive-date=2008-10-05|access-date=2008-10-09}}</ref>

== Education ==
Cecil Frank Powell was born on 5 December 1903 in [[Tonbridge]], England, the son of Frank Powell, a gunsmith, and Elizabeth Caroline Bisacre.<ref>{{Cite journal|last1=Frank|first1=F. C.|last2=Perkins|first2=D. H.|author-link1=Frederick Charles Frank|author-link2=Donald Hill Perkins|year=1971|title=Cecil Frank Powell 1903-1969|journal=[[Biographical Memoirs of Fellows of the Royal Society]]|volume=17|pages=541–563|doi=10.1098/rsbm.1971.0021}}</ref>

Powell was educated at a local primary school before gaining a scholarship to the [[Judd School]] in Tonbridge. He then entered [[Sidney Sussex College, Cambridge]], graduating in 1925 with [[First Class Honours]] in the [[Natural Sciences Tripos]]. After completing his bachelor's degree, he worked under [[Ernest Rutherford]] and [[C. T. R. Wilson]] in the [[Cavendish Laboratory]], conducting research on [[condensation]] phenomena. He received his [[Ph.D.]] in Physics in 1927.<ref name=NobelBiog>{{Cite web|title=Cecil Powell – Biographical|url=https://www.nobelprize.org/prizes/physics/1950/powell/biographical/|url-status=live|publisher=[[Nobel Foundation]]|archive-url=https://web.archive.org/web/20250717023535/https://www.nobelprize.org/prizes/physics/1950/powell/biographical/|archive-date=2025-07-17|access-date=2009-09-14}}</ref>

In 1932, Powell married Isobel Artner (1907–1995). They had two daughters, Jane and Annie.<ref name=NobelBiog/><ref name="CHIS" /> 

== Career and research ==
In 1927, Powell became a research assistant to [[Arthur Mannering Tyndall]] in the H. H. Wills Physical Laboratory at the [[University of Bristol]]. He was later appointed lecturer and, in 1948, 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]] 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 particle]]s, 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]], [[Hugh Muirhead]], and [[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 force]]s.<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 1950, Powell was awarded the [[Nobel Prize in Physics]] "for his development of the photographic method of studying nuclear processes and his discoveries regarding mesons made with this method." Lattes was working with him at the time of the discovery and had improved the sensitivity of the photographic emulsion. 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]] and [[Bibha Chowdhuri]] published three consecutive papers in ''[[Nature (journal)|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 Bose and Chowdhuri, Powell made the same discovery of [[pion]]s and [[muon]]s and further decay of muons to [[electron]]s… 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 [[proton]]s and mesons in an emulsion… They concluded that many of the [[charged particle]]s 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 [[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 served on the Scientific Policy Committee of the European Organization for Nuclear Research ([[CERN]]).<ref name=NobelBiog/>

== Global policy ==
He was one of the signatories of the agreement to convene a convention for drafting a [[world constitution]].<ref>{{Cite web |title=Letters from Thane Read asking Helen Keller to sign the World Constitution for world peace. 1961 |url=https://www.afb.org/HelenKellerArchive?a=d&d=A-HK01-07-B149-F04-022.1.8 |access-date=2023-07-01 |website=Helen Keller Archive |publisher=American Foundation for the Blind}}</ref><ref>{{Cite web |title=Letter from World Constitution Coordinating Committee to Helen, enclosing current materials |url=https://www.afb.org/HelenKellerArchive?a=d&d=A-HK01-07-B154-F05-028.1.6 |access-date=2023-07-03 |website=Helen Keller Archive |publisher=American Foundation for the Blind}}</ref> As a result, for the first time in human history, a [[World Constituent Assembly]] convened to draft and adopt the [[Constitution for the Federation of Earth]].<ref>{{Cite web |title=Preparing earth constitution {{!}} Global Strategies & Solutions {{!}} The Encyclopedia of World Problems |url=http://encyclopedia.uia.org/en/strategy/193465 |url-status=dead |access-date=2023-07-15 |website=The Encyclopedia of World Problems {{!}} Union of International Associations (UIA) |archive-date=19 July 2023 |archive-url=https://web.archive.org/web/20230719215501/http://encyclopedia.uia.org/en/strategy/193465 }}</ref>

== Death ==
[[File:C.F.Powell - Bench & Plaque.jpg|thumb|upright|[[Memorial bench]] dedicated to Powell outside the Capanna Vittoria restaurant, on the Alpe Giumello in [[Casargo]], Italy]]

On 9 August 1969, Powell died of a [[heart attack]] while on holiday with his wife in the [[Valsassina]] region of Italy, lodging in a house in Sanico, in the [[Province of Lecco]].<ref name="Valsassina News 26 May 2013">{{Cite web|author=<!--Staff writer(s); no by-line.--> |date=26 May 2013 |title=Giumello. La storia che non t'aspetti il Premio Nobel che amava la Valsassina |trans-title=Giumello. The surprising story of the Nobel Prize winner that loved Valsassina |website=valsassinanews.com |publisher=Valsassina News |location=Valsassina |language=it |url=https://www.valsassinanews.com/2013/05/26/giumellola-storia-che-non-taspetti-il-premio-nobel-che-amava-la-valsassina/ |access-date=14 August 2021 |url-status=live |archive-url=https://web.archive.org/web/20210814070308/https://www.valsassinanews.com/2013/05/26/giumellola-storia-che-non-taspetti-il-premio-nobel-che-amava-la-valsassina/ |archive-date=14 August 2021}}</ref><ref>{{Cite journal|last1=Camerini|first1=U.|title =Cecil Powell, Cosmic-Ray Physicist, Dies in Italy|journal=[[Physics Today]]|volume=22 |issue=11|pages=107–109|year=1969|bibcode=1969PhT....22k.107C|doi=10.1063/1.3035243}}</ref>

[[Giuseppe Occhialini]] had a wooden bench built with Powell's name carved into a [[commemorative plaque]], and then transported it to [[Premana]], a village in the mountains above [[Lake Como]].<ref name="Vegni 2006">{{Cite book|last1=Vegni |first1=Guido |editor1-last=Redondi |editor1-first=Pietro |editor1-link=Pietro Redondi |editor2-last=Sironi |editor2-first=Giorgio |editor3-last=Tucci |editor3-first=Pasquale |editor4-last=Vegni |editor4-first=Guido |display-editors=1 |others=[[Italian Physical Society|Società Italiana di Fisica]] |year=2006 |title=The Scientific Legacy of Beppo Occhialini |chapter=Giuseppe Occhialini in Milan in the sixties and beyond: His legacy for particle physics and his influence on young researchers and students |publisher=[[Springer Science+Business Media|Springer]] |page=124 |location=Bologna |language=en |isbn=978-3-540-37353-7 |lccn=2006933051 |oclc=875693069}}</ref> It was installed on the path where he died, outside the Rifugio Capanna Vittoria (now the Capanna Vittoria restaurant), on the Alpe Giumello, in [[Casargo]].<ref name="Valsassina News 26 May 2013" /> Occhialini's reason was, "...if that bench had already been there, Powell would probably have stopped to rest there."<ref name="Vegni 2006" />

== Recognition ==
=== Memberships ===
{| class="wikitable"
! Country
! Year
! Institute
! Type
! {{Reference column heading}}
|-
| {{Flag|United Kingdom}}
| 1949
| [[Royal Society]]
| [[Fellow of the Royal Society|Fellow]]
| <ref>{{Cite web|title=Search past Fellows|url=https://catalogues.royalsociety.org/CalmView/Record.aspx?src=CalmView.Persons&id=NA6049&pos=3|publisher=[[Royal Society]]|access-date=2025-11-28}}</ref>
|}

=== Awards ===
{| class="wikitable"
! Country
! Year
! Institute
! Award
! Citation
! {{Reference column heading}}
|-
| {{Flag|United Kingdom}}
| 1949
| [[Royal Society]]
| [[Hughes Medal]]
| "For his distinguished work on the photography of particle tracks in connection with the discovery of mesons and their transformation"
| <ref>{{Cite web|title=Hughes Medal|url=https://royalsociety.org/medals-and-prizes/hughes-medal/|publisher=[[Royal Society]]|access-date=2025-10-31}}</ref>
|-
| {{Flag|Sweden}}
| 1950
| [[Royal Swedish Academy of Sciences]]
| [[Nobel Prize in Physics]]
| "For his development of the photographic method of studying nuclear processes and his discoveries regarding mesons made with this method"
| <ref name=Nobel1950/>
|-
| {{Flag|United Kingdom}}
| 1961
| [[Royal Society]]
| [[Royal Medal]]
| "In recognition of his pioneering work on the development of the photographic emulsion technique in the investigation of cosmic rays, and the outstanding results derived therefrom on the elementary particles in cosmic radiation"
| <ref>{{Cite web|title=Royal Medal|url=https://royalsociety.org/medals-and-prizes/royal-medals/|url-status=live|publisher=[[Royal Society]]|archive-url=https://web.archive.org/web/20150925080312/https://royalsociety.org/grants-schemes-awards/awards/royal-medal/|archive-date=2015-09-25|access-date=2014-08-07}}</ref>
|-
| {{Flag|Soviet Union}}
| 1967
| [[Soviet Academy of Sciences]]
| [[Lomonosov Gold Medal]]
| "For outstanding achievements in the field of elementary particle physics"
| <ref>{{Cite web|title=Lomonosov Gold Medal|url=http://www.ras.ru/win/db/award_dsc.asp?H=award_dsc&P=id-1.ln-en&|url-status=dead|language=ru|publisher=[[Russian Academy of Sciences]]|archive-url=https://web.archive.org/web/20250125134102/https://www.ras.ru/win/db/award_dsc.asp?H=award_dsc&P=id-1.ln-en&|archive-date=2025-01-25|access-date=2009-09-14}}</ref>
|}

== Commemorations ==
* The Cecil F. Powell Memorial Medal was named in his honour by the [[European Physical Society]].
* In October 2011, a replacement [[commemorative plaque]] was installed in Downside Road, Bristol.<ref name="CHIS">{{cite web |title=Clifton and Hotwells Improvement Society (CHIS) |url=http://archive.cliftonhotwells.org.uk/chis_plaques.html |website=Clifton and Hotwells Improvement Society (CHIS) |access-date=8 December 2020}}</ref>
* In 2013, the [[Inner Wheel Club|International Inner Wheel Club]] of [[Lecco]], in [[Lombardy]], Northern Italy, erected a sign in memory of Powell, close to where he died, at the Capanna Vittoria restaurant, on the Alpe Giumello, in Casargo.<ref name="Valsassina News 26 May 2013" />

== See also ==
*[[Marietta Blau]]

==References==
{{reflist}}

==External links==
*{{Commons category inline}}
*{{Nobelprize}} including the Nobel Lecture, 11 December 1950 ''The Cosmic Radiation''
*[https://web.archive.org/web/20071127044926/http://photos.aip.org/history/Thumbnails/powell_cecil_a1.jpg Portrait photograph of Powell] at the American Institute of Physics

{{Nobel Prize in Physics Laureates 1926-1950}}
{{1950 Nobel Prize winners}}
{{Anti-nuclear movement}}
{{World Constitutional Convention call signatories}}
{{Authority control}}

{{DEFAULTSORT:Powell, Cecil Frank}}
[[Category:1903 births]]
[[Category:1969 deaths]]
[[Category:20th-century British physicists]]
[[Category:People from Tonbridge]]
[[Category:British Nobel laureates]]
[[Category:People associated with CERN]]
[[Category:British experimental physicists]]
[[Category:Nobel laureates in Physics]]
[[Category:British particle physicists]]
[[Category:People educated at The Judd School]]
[[Category:Royal Medal winners]]
[[Category:Alumni of Sidney Sussex College, Cambridge]]
[[Category:Fellows of the Royal Society]]
[[Category:Anti–nuclear weapons movement]]
[[Category:Academics of the University of Bristol]]
[[Category:World Constitutional Convention call signatories]]
[[Category:Cosmic ray physicists]]