Editing Hans Geiger

{{Short description|German nuclear physicist (1882–1945)}}
{{For-multi|the German footballer|Hans Geiger (footballer)|the Swiss surrealist artist|H. R. Giger}}
{{Infobox scientist
| name              = Hans Geiger
| image             = Hans_geiger.jpg
| caption           = Geiger in 1928
| birth_name        = Johannes Wilhelm Geiger
| birth_date        = {{Birth date|1882|09|30|df=yes}}
| birth_place       = [[Neustadt an der Haardt]], [[Kingdom of Bavaria]], [[German Empire]]
| death_date        = {{Death date and age|1945|09|24|1882|09|30|df=yes}}
| death_place       = [[Potsdam]], [[Ostzone]], [[Allied-occupied Germany]]
| alma_mater        = [[University of Erlangen]] ([[PhD]], 1906)
| known_for         = {{Plain list|
* Performing the [[Rutherford scattering experiments]] (1906–1913)
* [[Geiger counter]] (1908)
* [[Geiger–Nuttall law]] (1911)
* [[Bothe–Geiger coincidence experiment]] (1924)
* [[Geiger–Müller tube]] (1928)
}}
| father            = [[Wilhelm Geiger]]
| relatives         = [[Rudolf Geiger]] (brother)
| awards            = {{Plain list|
* [[Hughes Medal]] (1929)
* [[Duddell Medal and Prize]] (1937)
}}
| fields            = [[Nuclear physics]]
| work_institutions = {{Plain list|
* [[Victoria University of Manchester]] (1906–1912)
* [[Physikalisch-Technische Reichsanstalt]] (1912–1925)
* [[University of Kiel]] (1925–1929)
* [[University of Tübingen]] (1929–1936)
* [[Technische Universität Berlin]] (1936–1945)
}}
}}

'''Johannes Wilhelm Geiger''' ({{IPAc-en|ˈ|ɡ|aɪ|ɡ|ər}}; {{IPA|de|joˈhanəs ˈvɪlhɛlm ˈɡaɪɡɐ|lang}}; 30 September 1882 – 24 September 1945) was a German [[nuclear physicist]]. He is known  as the inventor of the [[Geiger counter]], a device used to detect [[ionizing radiation]], and for carrying out the [[Rutherford scattering experiments]], which led to the discovery of the [[atomic nucleus]]. He also performed the [[Bothe–Geiger coincidence experiment]], which confirmed the [[conservation of energy]] in light-particle interactions.

He was the brother of [[meteorologist]] and [[climatology|climatologist]] [[Rudolf Geiger]].

==Biography==
Geiger was born at [[Neustadt an der Haardt]], [[Germany]]. He was one of five children born to the [[Indologist]] [[Wilhelm Ludwig Geiger]], who was a professor at the [[University of Erlangen]]. In 1902, Geiger started studying [[physics]] and [[mathematics]] at the University of Erlangen and was awarded a doctorate in 1906.<ref>{{cite journal
|last1=Krebs
|date=July 1956
|title=Hans Geiger: Fiftieth Anniversary of the Publication of His Doctoral Thesis, 23 July 1906
|journal=[[Science (journal)|Science]]
|volume=124
|issue=3213
|pages=166
| pmid = 17843412
|doi = 10.1126/science.124.3213.166
| bibcode =  1956Sci...124..166K
|first1=AT
 }}</ref> His thesis was on electrical discharges through gases.<ref name="auto1">{{Cite journal |pmc = 3228631|year = 2011|last1 = Shampo|first1 = M. A.|title = Hans Geiger—German Physicist and the Geiger Counter|journal = Mayo Clinic Proceedings|volume = 86|issue = 12|pages = e54|last2 = Kyle|first2 = R. A.|last3 = Steensma|first3 = D. P.|pmid = 22196280|doi = 10.4065/mcp.2011.0638}}</ref> He received a fellowship to the [[Victoria University of Manchester|University of Manchester]] and worked as an assistant to [[Arthur Schuster]]. In 1907, after Schuster's retirement, Geiger began to work with his successor, [[Ernest Rutherford]], and in 1908, along with [[Ernest Marsden]], conducted the famous [[Geiger–Marsden experiment]] (also known as the "gold foil experiment"). This process allowed them to count alpha particles<ref>{{cite journal |author1=Rutherford E. |author2=Geiger H. |year=1908 |title=An electrical method of counting the number of α particles from radioactive substances |journal=Proceedings of the Royal Society of London, Series A  |volume=81 |issue=546 |pages=141–161 |url=https://books.google.com/books?id=jaezAAAAIAAJ&pg=PA141|doi=10.1098/rspa.1908.0065 |issn=1364-5021|bibcode = 1908RSPSA..81..141R |doi-access=free }}</ref><ref>{{cite journal |author=Geiger H. |year=1913 |title=Über eine einfache Methode zur Zählung von α- und β-Strahlen (On a simple method for counting α- and β-rays) |journal=Verhandlungen der Deutschen Physikalischen Gesellschaft |volume=15 |pages=534–539 }}</ref><ref>{{cite book |author=Campbell John |year=1999 |title=Rutherford Scientist Supreme, AAS Publications}}</ref><ref name="auto1"/> and led Rutherford to start thinking about the structure of the atom. He was elected to membership of the [[Manchester Literary and Philosophical Society]] on 29.11.1910

In 1911 Geiger and [[John Mitchell Nuttall]] discovered the [[Geiger–Nuttall law]] (or rule) and performed experiments that led to [[Rutherford model|Rutherford's atomic model]].<ref>H. Geiger and J.M. Nuttall (1911) "The ranges of the α particles from various radioactive substances and a relation between range and period of transformation", ''Philosophical Magazine'', series 6, vol. 22, no. 130, pages 613-621. See also: H. Geiger and J.M. Nuttall (1912) "The ranges of α particles from uranium", ''Philosophical Magazine'', series 6, vol. 23, no. 135, pages 439-445.</ref>

In 1912, Geiger was named head of radiation research at the ''[[Physikalisch-Technische Reichsanstalt]]'' (Imperial Physical Technical Institute – PTR) in [[Charlottenburg]]. There he worked with [[Walter Bothe]] (winner of the 1954 [[Nobel Prize in Physics]]) and [[James Chadwick]] (winner of the 1935 Nobel Prize in Physics).<ref name="auto">{{cite web | url=https://www.aps.org/publications/apsnews/201206/physicshistory.cfm | title=June 1911: Invention of the Geiger Counter}}</ref> Work was interrupted when Geiger served in the German military during [[World War I]] as an artillery officer from 1914 to 1918.

In 1924, Geiger and Bothe carried the [[Bothe–Geiger coincidence experiment]] that confirmed the [[Compton effect]] which helped earn [[Arthur Compton]] the 1927 Nobel Prize in Physics.<ref name="auto1" /> Bothe would also receive the Nobel Prize in Physics for their experiment in 1954, after Geiger's death.<ref name=":02">{{Cite journal |last=Maier |first=Elke |date=2011 |title=Flashback: Particle Billiards, Captured on Film |url=https://www.mpg.de/4444392/MPR_2011_3 |journal=MaxPlanckResearch |volume=3 |pages=92–93}}</ref>

In 1925, he began a teaching position at the [[University of Kiel]] where, in 1928 Geiger and his student [[Walther Müller]] created an improved version of the Geiger tube, the [[Geiger–Müller tube]]. This new device not only detected alpha particles, but beta and gamma particles as well, and is the basis for the Geiger counter.<ref>{{cite journal |author1=Geiger |author2=Müller W. |year=1928 |title=Elektronenzählrohr zur Messung schwächster Aktivitäten (Electron counting tube for the measurement of the weakest radioactivities) |journal=Die Naturwissenschaften (The Sciences) |volume=16 |issue=31 |pages=617–618 |doi=10.1007/BF01494093 |issn=0028-1042 |bibcode = 1928NW.....16..617G |s2cid=27274269 }}</ref><ref>See also:  
# Geiger, H. and Müller, W. (1928) "Das Elektronenzählrohr" (The electron counting tube), ''Physikalische Zeitschrift'', '''29''':  839-841. 
# Geiger, H. and Müller, W. (1929) "Technische Bemerkungen zum Elektronenzählrohr" (Technical notes on the electron counting tube), ''Physikalische Zeitschrift'', '''30''': 489-493. 
# Geiger, H. and Müller, W. (1929) "Demonstration des Elektronenzählrohrs" (Demonstration of the electron counting tube), ''Physikalische Zeitschrift'', '''30''': 523 ff.</ref>

In 1929 Geiger was named professor of physics and director of research at the [[University of Tübingen]] where he made his first observations of a [[cosmic ray]] shower. In 1936 he took a position with [[Technische Universität Berlin]] where he continued to research cosmic rays, [[nuclear fission]], and artificial radiation until his death in 1945.<ref name="auto1"/>

Beginning in 1939, after the discovery of [[atomic fission]], Geiger was a member of the [[German nuclear energy project|Uranium Club]], the German investigation of nuclear weapons during [[World War II]]. The group splintered in 1942 after its members came to believe that nuclear weapons would not play a significant role in ending the war.<ref name="auto"/>

Although Geiger signed a petition against the [[Nazi Germany|Nazi government]]'s interference with universities, he provided no support to colleague [[Hans Bethe]] (winner of the 1967 Nobel Prize in Physics) when he was fired for being [[Jews|Jewish]].<ref>{{cite web | url=https://www.atomicheritage.org/history/scientific-exodus | title=Scientific Exodus}}</ref><ref>{{cite web | url=https://www.scientificamerican.com/article/how-2-pro-nazi-nobelists-attacked-einstein-s-jewish-science-excerpt1/ | title=How 2 Pro-Nazi Nobelists Attacked Einstein's "Jewish Science" &#91;Excerpt&#93;| website=[[Scientific American]]}}</ref>

Geiger endured the [[Battle of Berlin]] and subsequent [[USSR|Soviet]] occupation in April/May 1945. A couple of months later he moved to [[Potsdam]], dying there on 24 September 1945.

==See also==
*[[Geiger (crater)]]

==References==
{{Reflist}}

==External links ==
*{{Commons category-inline}}
*[https://web.archive.org/web/20060828132837/http://alsos.wlu.edu/qsearch.aspx?browse=people%2FGeiger%2C+Hans Annotated bibliography for Hans Geiger from the Alsos Digital Library for Nuclear Issues]

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{{DEFAULTSORT:Geiger, Hans}}
[[Category:1882 births]]
[[Category:1945 deaths]]
[[Category:German nuclear physicists]]
[[Category:20th-century German inventors]]
[[Category:University of Erlangen-Nuremberg alumni]]
[[Category:People associated with the University of Manchester]]
[[Category:People from the Palatinate (region)]]
[[Category:Academic staff of Technische Universität Berlin]]
[[Category:Academic staff of the University of Kiel]]
[[Category:People from Neustadt an der Weinstraße]]
[[Category:20th-century German physicists]]