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Wilhelm Hanle

Wilhelm Hanle

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Wilhelm Hanle was a German
Germany
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...

 experimental physicist. He is known for the Hanle effect
Hanle effect
The Hanle effect is a reduction in the polarisaton of light when the atoms emitting the light are subject to a magnetic field in a particular direction, and when they have themselves been excited by polarised light....

. During World War II, he made contributions to the German nuclear energy project, also known as the Uranium Club. From 1941 until emeritus status in 1969, he was an ordinarius professor of experimental physics and held the chair of physics at the University of Giessen.

Education


From 1919 to 1924, Hanle studied at the Ruprecht-Karls-Universität Heidelberg and the Georg-August-Universität Göttingen. Philipp Lenard
Philipp Lenard
Philipp Eduard Anton von Lenard , known in Hungarian as Lénárd Fülöp Eduárd Antal, was a Hungarian - German physicist and the winner of the Nobel Prize for Physics in 1905 for his research on cathode rays and the discovery of many of their properties...

, Director of the Physikalische Institut (Physics Institute) at Heidelberg, had a dictatorial attitude towards his students and colleagues, and Hanle had a conflict with Lenard. Hanle transferred to Göttingen. In 1923, Hanle conducted an experiment which demonstrated the variation of polarization of the resonance fluorescent light from a mercury vapor in a weak magnetic field; this became known as the Hanle effect. He received his doctorate at Göttingen in 1924, under James Franck
James Franck
James Franck was a German Jewish physicist and Nobel laureate.-Biography:Franck was born to Jacob Franck and Rebecca Nachum Drucker. Franck completed his Ph.D...

, who as Director of the II. Physikalisches Institut (Second Physical Institute).

Career


Hanle was a teaching assistant at the University of Göttingen in 1924 and at the Eberhard-Karls-Universität Tübingen in 1925. He was at the Martin-Luther-Universität Halle-Wittenberg
University of Halle-Wittenberg
The Martin Luther University of Halle-Wittenberg , also referred to as MLU, is a public, research-oriented university in the cities of Halle and Wittenberg within Saxony-Anhalt, Germany...

from 1926 to 1929, and, upon completion of his Habilitation
Habilitation
Habilitation is the highest academic qualification a scholar can achieve by his or her own pursuit in several European and Asian countries. Earned after obtaining a research doctorate, such as a PhD, habilitation requires the candidate to write a professorial thesis based on independent...

, he became a Privatdozent
Privatdozent
Privatdozent or Private lecturer is a title conferred in some European university systems, especially in German-speaking countries, for someone who pursues an academic career and holds all formal qualifications to become a tenured university professor...

(unpaid lecturer) there in 1927. From 1929, he was an ausserordentlicher Professor (extraordinarius professor) and head of the physics department at the Friedrich-Schiller-Universität Jena.

At Jena, Georg Joos
Georg Joos
Georg Jakob Christof Joos was a German theoretical physicist. He wrote Lehrbuch der theoretischen Physik, first published in 1932 and one of the most influential theoretical physics textbooks of the 20th Century.-Education:Joos began his higher education in 1912 at the Technische Hochschule...

 was professor of theoretical physics, but in 1935, he made a compulsory transfer to head the Second Physical Institute at Göttingen to replace James Franck
James Franck
James Franck was a German Jewish physicist and Nobel laureate.-Biography:Franck was born to Jacob Franck and Rebecca Nachum Drucker. Franck completed his Ph.D...

, who had resigned as a result of the Law for the Restoration of the Professional Civil Service
Law for the Restoration of the Professional Civil Service
The Law for the Restoration of the Professional Civil Service , also known as Civil Service Law, Civil Service Restoration Act, and Law to Re-establish the Civil Service, was a law passed by the National Socialist regime on April 7, 1933, two months after Adolf...

 in 1933. Hanle and Joos would soon be part of the impetus to initiate the German nuclear energy project
German nuclear energy project
The German nuclear energy project, , was an attempted clandestine scientific effort led by Germany to develop and produce the atomic weapons during the events involving the World War II...

, shortly after Hanle went to Göttingen. From 1937 to 1941, Hanle was again at the University of Göttingen.

In December 1938, the German chemists Otto Hahn
Otto Hahn
Otto Hahn FRS was a German chemist and Nobel laureate, a pioneer in the fields of radioactivity and radiochemistry. He is regarded as "the father of nuclear chemistry". Hahn was a courageous opposer of Jewish persecution by the Nazis and after World War II he became a passionate campaigner...

 and Fritz Strassmann
Fritz Strassmann
Friedrich Wilhelm "Fritz" Strassmann was a German chemist who, with Otto Hahn in 1938, identified barium in the residue after bombarding uranium with neutrons, which led to the interpretation of their results as being from nuclear fission...

 sent a manuscript to Naturwissenschaften
Die Naturwissenschaften
Naturwissenschaften is a monthly peer-reviewed scientific journal published by Springer on behalf of several learned societies.- History :...

reporting they had detected the element barium
Barium
Barium is a chemical element with the symbol Ba and atomic number 56. It is the fifth element in Group 2, a soft silvery metallic alkaline earth metal. Barium is never found in nature in its pure form due to its reactivity with air. Its oxide is historically known as baryta but it reacts with...

 after bombarding uranium
Uranium
Uranium is a silvery-white metallic chemical element in the actinide series of the periodic table, with atomic number 92. It is assigned the chemical symbol U. A uranium atom has 92 protons and 92 electrons, of which 6 are valence electrons...

 with neutrons; simultaneously, they communicated these results to Lise Meitner
Lise Meitner
Lise Meitner FRS was an Austrian-born, later Swedish, physicist who worked on radioactivity and nuclear physics. Meitner was part of the team that discovered nuclear fission, an achievement for which her colleague Otto Hahn was awarded the Nobel Prize...

, who had in July of that year fled to The Netherlands and then went to Sweden
Sweden
Sweden , officially the Kingdom of Sweden , is a Nordic country on the Scandinavian Peninsula in Northern Europe. Sweden borders with Norway and Finland and is connected to Denmark by a bridge-tunnel across the Öresund....

. Meitner, and her nephew Otto Robert Frisch
Otto Robert Frisch
Otto Robert Frisch , Austrian-British physicist. With his collaborator Rudolf Peierls he designed the first theoretical mechanism for the detonation of an atomic bomb in 1940.- Overview :...

, correctly interpreted these results as being nuclear fission
Nuclear fission
In nuclear physics and nuclear chemistry, nuclear fission is a nuclear reaction in which the nucleus of an atom splits into smaller parts , often producing free neutrons and photons , and releasing a tremendous amount of energy...

. Frisch confirmed this experimentally on 13 January 1939.

Paul Harteck
Paul Harteck
Paul Karl Maria Harteck was a German physical chemist. He was arrested by the allied British and American Armed Forces and incarcerated at Farm Hall for six months in 1945 under Operation Epsilon.-Education:Harteck studied chemistry at the University of Vienna and the Humboldt University of Berlin...

 was director of the physical chemistry department at the University of Hamburg
University of Hamburg
The University of Hamburg is a university in Hamburg, Germany. It was founded on 28 March 1919 by Wilhelm Stern and others. It grew out of the previous Allgemeines Vorlesungswesen and the Kolonialinstitut as well as the Akademisches Gymnasium. There are around 38,000 students as of the start of...

 and an advisor to the Heereswaffenamt (HWA, Army Ordnance Office). On 24 April 1939, along with his teaching assistant Wilhelm Groth
Wilhelm Groth
Wilhelm Groth was a German physical chemist. During World War II, he worked on the German nuclear energy project, also known as the Uranium Club; his main activity was the development of centrifuges for the enrichment of uranium. After the war, he was a professor of physical chemistry at the...

, Harteck made contact with the Reichskriegsministerium (RKM, Reich Ministry of War) to alert them to the potential of military applications of nuclear chain reactions. Two days earlier, on 22 April 1939, after hearing a colloquium paper by Hanle on the use of uranium
Uranium
Uranium is a silvery-white metallic chemical element in the actinide series of the periodic table, with atomic number 92. It is assigned the chemical symbol U. A uranium atom has 92 protons and 92 electrons, of which 6 are valence electrons...

 fission
Nuclear fission
In nuclear physics and nuclear chemistry, nuclear fission is a nuclear reaction in which the nucleus of an atom splits into smaller parts , often producing free neutrons and photons , and releasing a tremendous amount of energy...

 in a Uranmaschine (uranium machine, i.e., nuclear reactor
Nuclear reactor
A nuclear reactor is a device to initiate and control a sustained nuclear chain reaction. Most commonly they are used for generating electricity and for the propulsion of ships. Usually heat from nuclear fission is passed to a working fluid , which runs through turbines that power either ship's...

), Georg Joos
Georg Joos
Georg Jakob Christof Joos was a German theoretical physicist. He wrote Lehrbuch der theoretischen Physik, first published in 1932 and one of the most influential theoretical physics textbooks of the 20th Century.-Education:Joos began his higher education in 1912 at the Technische Hochschule...

, along with Hanle, notified Wilhelm Dames, at the Reichserziehungsministerium
Reichserziehungsministerium
The Reichserziehungsministerium was officially known as the Reichsministerium für Wissenschaft, Erziehung und Volksbildung .-Background:...

(REM, Reich Ministry of Education), of potential military applications of nuclear energy. The communication was given to Abraham Esau
Abraham Esau
Robert Abraham Esau was a German physicist.After receipt of his doctorate from the University of Berlin, Esau worked at Telefunken, where he pioneered very high frequency waves used in radar, radio, and television, and he was president of the Deutscher Telefunken Verband...

, head of the physics section of the Reichsforschungsrat
Reichsforschungsrat
The Reichsforschungsrat was created in Germany in 1937 under the Education Ministry for the purpose of centralized planning of all basic and applied research, with the exception of aeronautical research...

(RFR, Reich Research Council) at the REM. On 29 April, a group, organized by Esau, met at the REM to discuss the potential of a sustained nuclear chain reaction
Nuclear chain reaction
A nuclear chain reaction occurs when one nuclear reaction causes an average of one or more nuclear reactions, thus leading to a self-propagating number of these reactions. The specific nuclear reaction may be the fission of heavy isotopes or the fusion of light isotopes...

. The group included the physicists Walther Bothe
Walther Bothe
Walther Wilhelm Georg Bothe was a German nuclear physicist, who shared the Nobel Prize in Physics in 1954 with Max Born....

, Robert Döpel
Robert Döpel
Georg Robert Döpel was a German experimental nuclear physicist. He was a participant in a group known as the “first Uranverein,” which was spawned by a meeting conducted by the Reichserziehungsministerium, in April 1939, to discuss the potential of a sustained nuclear reaction...

, Hans Geiger, Wolfgang Gentner
Wolfgang Gentner
Wolfgang Gentner was a German experimental nuclear physicist.Gentner received his doctorate in 1930 from the University of Frankfurt. From 1932 to 1935 he had a fellowship which allowed him to do postdoctoral research and study at Curie's Radium Institute at the University of Paris...

 (probably sent by Walther Bothe
Walther Bothe
Walther Wilhelm Georg Bothe was a German nuclear physicist, who shared the Nobel Prize in Physics in 1954 with Max Born....

), Wilhelm Hanle, Gerhard Hoffmann
Gerhard Hoffmann
Gerhard Hoffmann was a German nuclear physicist. During World War II, he contributed to the German nuclear energy project, also known as the Uranium Club.-Education:...

, and Georg Joos
Georg Joos
Georg Jakob Christof Joos was a German theoretical physicist. He wrote Lehrbuch der theoretischen Physik, first published in 1932 and one of the most influential theoretical physics textbooks of the 20th Century.-Education:Joos began his higher education in 1912 at the Technische Hochschule...

; Peter Debye
Peter Debye
Peter Joseph William Debye FRS was a Dutch physicist and physical chemist, and Nobel laureate in Chemistry.-Early life:...

 was invited, but he did not attend. After this, informal work began at Göttingen by Joos, Hanle, and their colleague Reinhold Mannfopff; the group of physicists was known informally as the first Uranverein (Uranium Club) and formally as Arbeitsgemeinschaft für Kernphysik. The group's work was discontinued in August 1939, when the three were called to military training.

The second Uranverein began after the HWA squeezed out the RFR of the REM and started the formal German nuclear energy project
German nuclear energy project
The German nuclear energy project, , was an attempted clandestine scientific effort led by Germany to develop and produce the atomic weapons during the events involving the World War II...

 under military auspices. The second Uranverein was formed on 1 September 1939, the day World War II began, and it had its first meeting on 16 September 1939. The meeting was organized by Kurt Diebner
Kurt Diebner
Kurt Diebner was a German nuclear physicist who is well known for directing and administrating the German nuclear energy project, a secretive program aiming to built weapon of mass destruction for the Nazi Germany during the course of World War II...

, advisor to the HWA, and held in Berlin. The invitees included Walther Bothe
Walther Bothe
Walther Wilhelm Georg Bothe was a German nuclear physicist, who shared the Nobel Prize in Physics in 1954 with Max Born....

, Siegfried Flügge
Siegfried Flügge
Siegfried Flügge was a German theoretical physicist and made contributions to nuclear physics. He worked at the Kaiser-Wilhelm Institut für Chemie and worked in the German Uranverein...

, Hans Geiger, Otto Hahn
Otto Hahn
Otto Hahn FRS was a German chemist and Nobel laureate, a pioneer in the fields of radioactivity and radiochemistry. He is regarded as "the father of nuclear chemistry". Hahn was a courageous opposer of Jewish persecution by the Nazis and after World War II he became a passionate campaigner...

, Paul Harteck
Paul Harteck
Paul Karl Maria Harteck was a German physical chemist. He was arrested by the allied British and American Armed Forces and incarcerated at Farm Hall for six months in 1945 under Operation Epsilon.-Education:Harteck studied chemistry at the University of Vienna and the Humboldt University of Berlin...

, Gerhard Hoffmann
Gerhard Hoffmann
Gerhard Hoffmann was a German nuclear physicist. During World War II, he contributed to the German nuclear energy project, also known as the Uranium Club.-Education:...

, Josef Mattauch
Josef Mattauch
Josef Mattauch was a German physicist known for his work in the investigation of the isotopic abundances by mass spectrometry. He developed the Mattauch isobar rule in 1934.-Mattauch-Herzog geometry mass spectrometer:...

, and Georg Stetter
Georg Stetter
Georg Stetter was an Austrian-German nuclear physicist. Stetter was Director of the Second Physics Institute of the University of Vienna. He was a principal member of the German nuclear energy project, also known as the Uranium Club. In the latter years of World War II, he was also the Director...

. A second meeting was held soon thereafter and included Klaus Clusius
Klaus Clusius
Klaus Clusius was a German physical chemist from Breslau , Silesia. During World War II, he worked on the German nuclear energy project, also known as the Uranium Club; he worked on isotope separation techniques and heavy water production...

, Robert Döpel
Robert Döpel
Georg Robert Döpel was a German experimental nuclear physicist. He was a participant in a group known as the “first Uranverein,” which was spawned by a meeting conducted by the Reichserziehungsministerium, in April 1939, to discuss the potential of a sustained nuclear reaction...

, Werner Heisenberg
Werner Heisenberg
Werner Karl Heisenberg was a German theoretical physicist who made foundational contributions to quantum mechanics and is best known for asserting the uncertainty principle of quantum theory...

, and Carl Friedrich von Weizsäcker
Carl Friedrich von Weizsäcker
Carl Friedrich Freiherr von Weizsäcker was a German physicist and philosopher. He was the longest-living member of the research team which performed nuclear research in Germany during the Second World War, under Werner Heisenberg's leadership...

. Also at this time, the Kaiser-Wilhelm Institut für Physik (KWIP, Kaiser Wilhelm Institute for Physics, after World War II the Max Planck Institute for Physics
Max Planck Institute for Physics
Max Planck Institute for Physics is a physics institute in Munich, Germany that specializes in High Energy Physics and Astroparticle physics. It is part of the Max-Planck-Gesellschaft and is also known as the Werner Heisenberg Institute, after its first director.It was founded as the Kaiser Wilhelm...

), in Berlin-Dahlem
Dahlem (Berlin)
Dahlem is a locality of the Steglitz-Zehlendorf borough in southwestern Berlin. Until Berlin's 2001 administrative reform it was a part of the former borough of Zehlendorf. Dahlem is one of the most affluent parts of the city and home to the main campus of the Free University of Berlin with the...

, was placed under HWA authority, with Diebner as the administrative director, and the military control of the nuclear research commenced.

Hanle contributed to the Uranverein under the auspices of the HWA with experimental studies which showed that boron
Boron
Boron is the chemical element with atomic number 5 and the chemical symbol B. Boron is a metalloid. Because boron is not produced by stellar nucleosynthesis, it is a low-abundance element in both the solar system and the Earth's crust. However, boron is concentrated on Earth by the...

 and cadmium
Cadmium
Cadmium is a chemical element with the symbol Cd and atomic number 48. This soft, bluish-white metal is chemically similar to the two other stable metals in group 12, zinc and mercury. Similar to zinc, it prefers oxidation state +2 in most of its compounds and similar to mercury it shows a low...

 were strong absorbers of thermal neutrons
Neutron temperature
The neutron detection temperature, also called the neutron energy, indicates a free neutron's kinetic energy, usually given in electron volts. The term temperature is used, since hot, thermal and cold neutrons are moderated in a medium with a certain temperature. The neutron energy distribution is...

.

From 1941 to 1969, Hanle was an ordentlicher Professor (ordinarius professor) of experimental physics and held the chair of physics at the Justus Liebig-Universität Gießen
University of Giessen
The University of Giessen is officially called the Justus Liebig University Giessen after its most famous faculty member, Justus von Liebig, the founder of modern agricultural chemistry and inventor of artificial fertiliser.-History:The University of Gießen is among the oldest institutions of...

. Hanle made significant contributions to the rebuilding of the University after World War II.

Honors


Hanle received a number of honors, including:
  • 1970 – Honorary Doctor of Engineering from the University of Stuttgart

  • 1987 – Honorary Senator of the University of Giessen for his work in reconstruction of the University after World War II

Internal Report


The following was published in Kernphysikalische Forschungsberichte
Kernphysikalische Forschungsberichte
Kernphysikalische Forschungsberichte was an internal publication of the German Uranverein, which was initiated under the Heereswaffenamt in 1939; in 1942, supervision of the Uranverein was turned over to the Reichsforschungsrat under the Reichserziehungsministerium...

(Research Reports in Nuclear Physics), an internal publication of the German Uranverein
German nuclear energy project
The German nuclear energy project, , was an attempted clandestine scientific effort led by Germany to develop and produce the atomic weapons during the events involving the World War II...

. Reports in this publication were classified Top Secret, they had very limited distribution, and the authors were not allowed to keep copies. The reports were confiscated under the Allied Operation Alsos
Operation Alsos
Operation Alsos was an effort at the end of World War II by the Allies , branched off from the Manhattan Project, to investigate the German nuclear energy project, seize German nuclear resources, materials and personnel to further American research and to prevent their capture by the Soviets, and...

 and sent to the United States Atomic Energy Commission
United States Atomic Energy Commission
The United States Atomic Energy Commission was an agency of the United States government established after World War II by Congress to foster and control the peace time development of atomic science and technology. President Harry S...

 for evaluation. In 1971, the reports were declassified and returned to Germany. The reports are available at the Karlsruhe Nuclear Research Center and the American Institute of Physics
American Institute of Physics
The American Institute of Physics promotes science, the profession of physics, publishes physics journals, and produces publications for scientific and engineering societies. The AIP is made up of various member societies...

.
  • Wilhelm Hanle Über den Nachweis von Bor und Cadmium in Kohle G-85 (18 April 1941)

Books

  • Wilhelm Hanle Die Erde im Strahlungsfeld von Sonne und Kosmos (Schmitz, 1948)

  • Wilhelm Hanle Atomenergie (Schmitz, 1949)

  • Wilhelm Hanle Künstliche Radioaktivität (Piscator-Verl., 1952)

  • Ulrich Jetter and Wilheml Hanle Atomwaffen, Anwendung, Wirkungsweise, Schutzmassnahmen (Physik-Verl., 1952)

  • Karl Lindackers, Wilheml Hanle, and Max Pllermann Praktische Durchführung von Abschirmungsberechnungen (Hanser, Carl GmbH + Co., 1962)

  • Wilhelm Hanle Isotopentechnik (Thiemig, 1964)

  • Wilhelm Hanle, Martin Oberhofer, and Wolfgang Jacobi Strahlenschutzpraxis. T. 3. Umgang mit Strahlern (Thiemig, 1968)

  • Wilhelm Hanle and Max Pollermann Isotopentechnik. Anwendung von Radionukliden und stabilen Nukliden (Hanser, Carl GmbH + Co., 1976)

  • Wilhelm Hanle Isotopentechnik. Anwendung von Radionukliden und stabilen Nukliden (K. Thiemig, Mchn., 1982)

  • Werner Heisenberg, Robert Döpel, Wilhelm Hanle, and Käthe Mitzenheim Werner Heisenberg in Leipzig 1927-1942 (Wiley-VCH, 1993)