Johannes Wilhelm Geiger was a German physicist born in 1882 who co-invented the Geiger counter and contributed to the Geiger-Marsden experiment which discovered the atomic nucleus. He studied physics in university and received his doctorate in 1906. In 1907, he began working with Ernest Rutherford at the University of Manchester and in 1909 conducted the famous Geiger-Marsden experiment with Ernest Marsden. Together they created the Geiger counter, which could detect individual alpha particles. Later, Geiger and his student Walther Müller created an improved version called the Geiger-Müller counter. Geiger made many contributions to the fields of radioactivity and nuclear physics before his death in 1945.

1. JohannesJohannes
Wilhelm GeigerWilhelm Geiger
(Hans)(Hans)DOBDOB::
September 30, 1882September 30, 1882
DODDOD::
September 24, 1945September 24, 1945
Greatest AccomplishmentGreatest Accomplishment::
co-inventor of the Geiger counter andco-inventor of the Geiger counter and
for the Geiger-Marsden experimentfor the Geiger-Marsden experiment
which discovered the Atomic nucleus.which discovered the Atomic nucleus.

2. BackgroundBackground
NationalityNationality::
GermanGerman

3. LifeLife::
 born at Neustadt-an-der-Haardt, Germanyborn at Neustadt-an-der-Haardt, Germany
 He was one of five childrenHe was one of five children
 Father: Ideologist Wilhelm Ludwig Geiger, who was professor at theFather: Ideologist Wilhelm Ludwig Geiger, who was professor at the
University of Erlangen. In 1902University of Erlangen. In 1902
 Geiger started studying physics and mathematics in University of ErlangenGeiger started studying physics and mathematics in University of Erlangen
and was awarded a doctorate in 1906. In 1907 he began work with Ernestand was awarded a doctorate in 1906. In 1907 he began work with Ernest
Rutherford at the University of Manchester and in 1909, along with ErnestRutherford at the University of Manchester and in 1909, along with Ernest
Marsden, conducted the famous Geiger-Marsden experiment called theMarsden, conducted the famous Geiger-Marsden experiment called the
'gold foil experiment'. Together they created the Geiger counter. In 1911'gold foil experiment'. Together they created the Geiger counter. In 1911
Geiger and John Mitchell Nuttall discovered the Geiger-Nuttall law (or rule)Geiger and John Mitchell Nuttall discovered the Geiger-Nuttall law (or rule)
and performed experiments that led to Rutherford's atomic model. In 1928and performed experiments that led to Rutherford's atomic model. In 1928
Geiger and his student Walther Müller created an improved version of theGeiger and his student Walther Müller created an improved version of the
Geiger counter, the Geiger-Müller counter. Geiger also worked with JamesGeiger counter, the Geiger-Müller counter. Geiger also worked with James
Chadwick. In 1912 he became leader of the Physical-TechnicalChadwick. In 1912 he became leader of the Physical-Technical
Reichsanstalt in Berlin, 1925 professor in Kiel, 1929 in Tübingen, and fromReichsanstalt in Berlin, 1925 professor in Kiel, 1929 in Tübingen, and from
1936 in Berlin. He was a member of the Uranium Club, which was working1936 in Berlin. He was a member of the Uranium Club, which was working
on an atomic bomb for Nazi Germany.on an atomic bomb for Nazi Germany.
 Geiger died in Potsdam, Germany a few months after World War II ended.Geiger died in Potsdam, Germany a few months after World War II ended.

4. EducationEducation::
 Geiger was educated first at Erlangen Gymnasium,Geiger was educated first at Erlangen Gymnasium,
from which he graduated in 1901. After completingfrom which he graduated in 1901. After completing
his required military service, he studied physicshis required military service, he studied physics
(the study of the relationship between matter and(the study of the relationship between matter and
energy) at the University of Munich and at theenergy) at the University of Munich and at the
University of Erlangen, receiving a doctorate fromUniversity of Erlangen, receiving a doctorate from
Erlangen in 1906 for his study of electrical releasesErlangen in 1906 for his study of electrical releases
through gases.through gases.

5. ContributionsContributions ::
German physicist who introduced the first successful detector (the GeigerGerman physicist who introduced the first successful detector (the Geiger
counter) of individual alpha particles and other ionizing radiations.counter) of individual alpha particles and other ionizing radiations.
He used it in experiments that led to the identification of the alpha particle asHe used it in experiments that led to the identification of the alpha particle as
the nucleus of the helium atom and to Rutherford's determination (1912) thatthe nucleus of the helium atom and to Rutherford's determination (1912) that
the nucleus of an occupies a very small volume at the centre.the nucleus of an occupies a very small volume at the centre.
The Geiger-Müller counter (developed with Walther Müller) had improvedThe Geiger-Müller counter (developed with Walther Müller) had improved
sensitivity, performance, and durability. It detects not only alpha particles butsensitivity, performance, and durability. It detects not only alpha particles but
beta particles (electrons) and ionizing electromagnetic photons. Later in life, hebeta particles (electrons) and ionizing electromagnetic photons. Later in life, he
investigated cosmic rays, artificial radioactivity, and nuclear fissioninvestigated cosmic rays, artificial radioactivity, and nuclear fission

6. AwardsAwards::
 Council of the Physical Society hasCouncil of the Physical Society has
this year awarded the fifteenththis year awarded the fifteenth
Duddell Medal to Prof. HansDuddell Medal to Prof. Hans
Geiger, of the University ofGeiger, of the University of
Tubingen. The medal is awarded toTubingen. The medal is awarded to
"persons who have contributed to"persons who have contributed to
the advancement of knowledge bythe advancement of knowledge by
the invention or design of scientificthe invention or design of scientific
instruments, or by the discovery ofinstruments, or by the discovery of
materials used in theirmaterials used in their
construction".construction".

7. Works CitedWorks Cited
 http://en.wikipedia.org/wiki/Hans_Geigerhttp://en.wikipedia.org/wiki/Hans_Geiger
 http://www.midlifegamer.net/wp-http://www.midlifegamer.net/wp-
content/uploads/2010/03/German_flag.jpgcontent/uploads/2010/03/German_flag.jpg
 http://www.nature.com/nature/journal/v141/n3577/abs/141929b0.hthttp://www.nature.com/nature/journal/v141/n3577/abs/141929b0.ht
mlml
 http://www.notablebiographies.com/Fi-Gi/Geiger-Hans.htmlhttp://www.notablebiographies.com/Fi-Gi/Geiger-Hans.html
 http://www.todayinsci.com/9/9_30.htmhttp://www.todayinsci.com/9/9_30.htm

8. Student IDStudent ID
9422395294223952