Johannes Wilhelm Geiger was a German physicist born in 1882 who co-invented the Geiger counter, a device that detects and counts atomic particles. He studied physics in Germany and England, where he collaborated with Ernest Rutherford. In 1912, Geiger returned to Germany and became the director of a new radioactivity laboratory, where he invented the Geiger counter. Over his career, he held professorships of physics at several German universities and made numerous contributions to the field of radioactivity and radiation detection.

1. Johannes Wilhelm GeigerJohannes Wilhelm Geiger
 BOB: September 30,BOB: September 30,
18821882
 Died: September 24,Died: September 24,
19451945
 GreatestGreatest
accomplishment : Co-accomplishment : Co-
Inventor of the GeigerInventor of the Geiger
counter, a device usedcounter, a device used
for detecting andfor detecting and
counting atomiccounting atomic
particlesparticles

2. BackgroundBackground
 Johannes Geiger is of German decent and was born inJohannes Geiger is of German decent and was born in
Neustadt, Germany to Indologist Wilhelm LudwigNeustadt, Germany to Indologist Wilhelm Ludwig
Geiger and his wife.Geiger and his wife.
 He was the eldest of five childrenHe was the eldest of five children
 His father Wilhelm Geiger was a professor at theHis father Wilhelm Geiger was a professor at the
University of ErlangenUniversity of Erlangen

3. Personal LifePersonal Life
 He completed his required military service and then studiedHe completed his required military service and then studied
physics at the University of Munich. He moved to Manchesterphysics at the University of Munich. He moved to Manchester
University in England where he met Ernest Rutherford whomUniversity in England where he met Ernest Rutherford whom
he developed an Professional and Personal friendship with.he developed an Professional and Personal friendship with.
 When he moved back to Germany in 1912 he became aWhen he moved back to Germany in 1912 he became a
director of the new laboratory for Radioactivity. Unfortunatelydirector of the new laboratory for Radioactivity. Unfortunately
his program was interrupted by World War 1 which he tookhis program was interrupted by World War 1 which he took
part in fighting with the German Troopspart in fighting with the German Troops..
 When he returned to Reichsanstalt after the war, he marriedWhen he returned to Reichsanstalt after the war, he married
Elisabeth Heffter two years later whom he had three sons with.Elisabeth Heffter two years later whom he had three sons with.

4. EducationEducation
 Geiger was educated first at Erlangen Gymnasium,Geiger was educated first at Erlangen Gymnasium,
from which he graduated in 1901.from which he graduated in 1901.
 Geiger studied Physics at the University of MunichGeiger studied Physics at the University of Munich
and Erlanger where he received a doctorate fromand Erlanger where he received a doctorate from
Erlanger, he then moved to Manchester University inErlanger, he then moved to Manchester University in
England where he met Ernest Rutherford.England where he met Ernest Rutherford.

5. Positions Held and Contributions to thePositions Held and Contributions to the
Science CommunityScience Community
 In 1912 Geiger returned to Germany fromIn 1912 Geiger returned to Germany from
Manchester, England as director of the newManchester, England as director of the new
Laboratory for Radioactivity at the Physikalisch-Laboratory for Radioactivity at the Physikalisch-
Technische Reichsanstalt in Berlin, Germany.Technische Reichsanstalt in Berlin, Germany.
 Co-Inventor of the Geiger Counter machine.Co-Inventor of the Geiger Counter machine.
Geiger designed the “Geiger Counter”, anGeiger designed the “Geiger Counter”, an
electrical machine designed to count releasedelectrical machine designed to count released
alpha particles.alpha particles.
 When he returned back to Germany in 1912 heWhen he returned back to Germany in 1912 he
invented an instrument for measuring not onlyinvented an instrument for measuring not only
alpha particles but other types of radiation.alpha particles but other types of radiation.
 Geiger became professor of physics at theGeiger became professor of physics at the
University of Kiel, Germany. Geier then leftUniversity of Kiel, Germany. Geier then left
Kiel for the University of Tubingen where heKiel for the University of Tubingen where he
worked as a professor of physics.worked as a professor of physics.
 He returned to Berlin where he was offered theHe returned to Berlin where he was offered the
chair of physics at the Technischte Hochschulechair of physics at the Technischte Hochschule..

6. Positions Held and Contributions to thePositions Held and Contributions to the
Science CommunityScience Community
 In 1912 Geiger returned to Germany fromIn 1912 Geiger returned to Germany from
Manchester, England as director of the newManchester, England as director of the new
Laboratory for Radioactivity at the Physikalisch-Laboratory for Radioactivity at the Physikalisch-
Technische Reichsanstalt in Berlin, Germany.Technische Reichsanstalt in Berlin, Germany.
 Co-Inventor of the Geiger Counter machine.Co-Inventor of the Geiger Counter machine.
Geiger designed the “Geiger Counter”, anGeiger designed the “Geiger Counter”, an
electrical machine designed to count releasedelectrical machine designed to count released
alpha particles.alpha particles.
 When he returned back to Germany in 1912 heWhen he returned back to Germany in 1912 he
invented an instrument for measuring not onlyinvented an instrument for measuring not only
alpha particles but other types of radiation.alpha particles but other types of radiation.
 Geiger became professor of physics at theGeiger became professor of physics at the
University of Kiel, Germany. Geier then leftUniversity of Kiel, Germany. Geier then left
Kiel for the University of Tubingen where heKiel for the University of Tubingen where he
worked as a professor of physics.worked as a professor of physics.
 He returned to Berlin where he was offered theHe returned to Berlin where he was offered the
chair of physics at the Technischte Hochschulechair of physics at the Technischte Hochschule..