J. Hans D. Jensen
Encyclopedia
Johannes Hans Daniel Jensen (25 June 1907 in Hamburg
Hamburg
-History:The first historic name for the city was, according to Claudius Ptolemy's reports, Treva.But the city takes its modern name, Hamburg, from the first permanent building on the site, a castle whose construction was ordered by the Emperor Charlemagne in AD 808...

 – 11 February 1973 in Heidelberg
Heidelberg
-Early history:Between 600,000 and 200,000 years ago, "Heidelberg Man" died at nearby Mauer. His jaw bone was discovered in 1907; with scientific dating, his remains were determined to be the earliest evidence of human life in Europe. In the 5th century BC, a Celtic fortress of refuge and place of...

) was a German nuclear physicist. During World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...

, he worked on 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...

, known as the Uranium Club, in which he made contributions to the separation 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...

 isotopes. After the war Jensen was a professor at the University of Heidelberg. He was a visiting professor at the University of Wisconsin–Madison
University of Wisconsin–Madison
The University of Wisconsin–Madison is a public research university located in Madison, Wisconsin, United States. Founded in 1848, UW–Madison is the flagship campus of the University of Wisconsin System. It became a land-grant institution in 1866...

, the Institute for Advanced Study
Institute for Advanced Study
The Institute for Advanced Study, located in Princeton, New Jersey, United States, is an independent postgraduate center for theoretical research and intellectual inquiry. It was founded in 1930 by Abraham Flexner...

, Indiana University
Indiana University
Indiana University is a multi-campus public university system in the state of Indiana, United States. Indiana University has a combined student body of more than 100,000 students, including approximately 42,000 students enrolled at the Indiana University Bloomington campus and approximately 37,000...

, and the California Institute of Technology
California Institute of Technology
The California Institute of Technology is a private research university located in Pasadena, California, United States. Caltech has six academic divisions with strong emphases on science and engineering...

.

Jensen shared half of the 1963 Nobel Prize for Physics with Maria Göppert-Mayer
Maria Göppert-Mayer
Maria Goeppert-Mayer was a German-born American theoretical physicist, and Nobel laureate in Physics for proposing the nuclear shell model of the atomic nucleus...

 for their proposal of the nuclear shell model.

Education

Jensen studied physics, mathematics, physical chemistry, and philosophy at the Albert-Ludwigs-Universität Freiburg
University of Freiburg
The University of Freiburg , sometimes referred to in English as the Albert Ludwig University of Freiburg, is a public research university located in Freiburg im Breisgau, Baden-Württemberg, Germany.The university was founded in 1457 by the Habsburg dynasty as the...

and 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...

 from 1926 to 1931, and he received his doctorate at the latter in 1932 under Wilhelm Lenz
Wilhelm Lenz
Wilhelm Lenz was a German physicist, most notable for his invention of the Ising model and for his application of the Laplace–Runge–Lenz vector to the quantum mechanical treatment of hydrogen-like atoms.In 1906, Lenz graduated from the Klinger-Oberralschule, a non-classical secondary school...

. Jensen completed 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...

 in 1936 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...

.

Career

In 1937 Jensen was 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) at the University of Hamburg and began working with 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...

, director of the university's physical chemistry department and advisor to the Heereswaffenamt (HWA, Army Ordnance Office) on explosives. Harteck and 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...

 made contact with the Reichskriegsministerium (RKM, Reich Ministry of War) on 24 April 1939 to tell them of potential military applications of 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...

s. Military control of 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...

, also known as the Uranverein (Uranium Club), began on 1 September 1939, the day that Nazi Germany initiated WWII by invading Poland. Harteck, one of the principals in the Uranverein, brought Jensen into the project. Jensen’s main thrust was on double centrifuge
Centrifuge
A centrifuge is a piece of equipment, generally driven by an electric motor , that puts an object in rotation around a fixed axis, applying a force perpendicular to the axis...

s for separation
Isotope separation
Isotope separation is the process of concentrating specific isotopes of a chemical element by removing other isotopes, for example separating natural uranium into enriched uranium and depleted uranium. This is a crucial process in the manufacture of uranium fuel for nuclear power stations, and is...

 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...

 isotopes (see the section below citing internal reports of the Uranverein). Harteck and Jensen developed a double centrifuge based on a rocking process (Schaukelverfahren) to facilitate the separation effect.

In 1941 Jensen was named extraordinarius professor of theoretical physics at the Technische Hochschule Hannover (today, the University of Hanover), and in 1946 he became an ordinarius professor there. In 1949 he was appointed ordinarius professor at the Ruprecht Karl University of Heidelberg; since 1969 he was emeritus praecox. He was a guest professor at the University of Wisconsin–Madison
University of Wisconsin–Madison
The University of Wisconsin–Madison is a public research university located in Madison, Wisconsin, United States. Founded in 1848, UW–Madison is the flagship campus of the University of Wisconsin System. It became a land-grant institution in 1866...

 (1950), the Institute for Advanced Study
Institute for Advanced Study
The Institute for Advanced Study, located in Princeton, New Jersey, United States, is an independent postgraduate center for theoretical research and intellectual inquiry. It was founded in 1930 by Abraham Flexner...

 (1952), and Indiana University
Indiana University
Indiana University is a multi-campus public university system in the state of Indiana, United States. Indiana University has a combined student body of more than 100,000 students, including approximately 42,000 students enrolled at the Indiana University Bloomington campus and approximately 37,000...

 and the California Institute of Technology
California Institute of Technology
The California Institute of Technology is a private research university located in Pasadena, California, United States. Caltech has six academic divisions with strong emphases on science and engineering...

 (1953).

In 1963 Jensen shared half of the Nobel Prize in Physics
Nobel Prize in Physics
The Nobel Prize in Physics is awarded once a year by the Royal Swedish Academy of Sciences. It is one of the five Nobel Prizes established by the will of Alfred Nobel in 1895 and awarded since 1901; the others are the Nobel Prize in Chemistry, Nobel Prize in Literature, Nobel Peace Prize, and...

 with Maria Göppert-Mayer for their proposal of the nuclear shell model; the remaining half of the prize was awarded to Eugene Wigner for unrelated work in nuclear and particle physics, especially through the application of fundamental symmetry principles.

Party memberships

Adolf Hitler
Adolf Hitler
Adolf Hitler was an Austrian-born German politician and the leader of the National Socialist German Workers Party , commonly referred to as the Nazi Party). He was Chancellor of Germany from 1933 to 1945, and head of state from 1934 to 1945...

 took power on 30 January 1933. On 7 April of that year 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...

 was enacted; this law, and its subsequent related ordinances, politicized the education system in Germany. Other factors enforcing the politicization of education were Nationalsozialistische Deutsche Arbeiterpartei (NSDAP, National Socialist German Workers Party) organizations in academia and the rise of the Deutsche Physik
Deutsche Physik
Deutsche Physik or Aryan Physics was a nationalist movement in the German physics community in the early 1930s against the work of Albert Einstein, labeled "Jewish Physics"...

movement, which was anti-Semitic and had a bias against theoretical physics
Theoretical physics
Theoretical physics is a branch of physics which employs mathematical models and abstractions of physics to rationalize, explain and predict natural phenomena...

, especially including quantum mechanics
Quantum mechanics
Quantum mechanics, also known as quantum physics or quantum theory, is a branch of physics providing a mathematical description of much of the dual particle-like and wave-like behavior and interactions of energy and matter. It departs from classical mechanics primarily at the atomic and subatomic...

. The Party organizations were the Nationalsozialistischer Deutscher Studentenbund (NSDStB, National Socialist German Student League) founded in 1926, the Nationalsozialistischer Lehrerbund (NSLB, National Socialist Teachers League
National Socialist Teachers League
The National Socialist Teachers League, Nationalsozialistische Lehrerbund , was established as a wing of the Nationalsozialistische Deutsche Arbeiterpartei in 1927. This organization lasted until 1943. Its seat was in Bayreuth. The founder and first "Reichswalter" of the organization was Hans Schemm...

) founded in 1927, and the Nationalsozialistischer Deutscher Dozentenbund (NSDDB, National Socialist German University Lecturers League) founded in 1933. While membership in the NSDDB was not mandatory, it was tactically advantageous, if not unavoidable, as the district leaders had a decisive role in the acceptance of an Habilitationsschrift, which was a prerequisite to attaining the rank of 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...

necessary to becoming a university lecturer.

While all German universities were politicized, not all were as strict in carrying out this end as was the University of Hamburg, where Jensen received his doctorate and Habilitationsschrift. Upon his 1936 habilitation he had been a member of NSDDB for three years, the NSLB for two years, and a candidate for membership in NSDAP, which he received the next year. The university leader of NSLB had made it clear that active participation was expected from Jensen, and that is what they got.

After World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...

 the denazification
Denazification
Denazification was an Allied initiative to rid German and Austrian society, culture, press, economy, judiciary, and politics of any remnants of the National Socialist ideology. It was carried out specifically by removing those involved from positions of influence and by disbanding or rendering...

 process began. When Jensen faced the proceedings, he turned to 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...

, a prominent member of the Uranverein, for a testament to his character – a document known as a Persilschein (whitewash certificate). Heisenberg was a particularly powerful writer of these documents, as he had never been a member of NSDAP, he had publicly clashed with NSDAP and the Schutzstaffel
Schutzstaffel
The Schutzstaffel |Sig runes]]) was a major paramilitary organization under Adolf Hitler and the Nazi Party. Built upon the Nazi ideology, the SS under Heinrich Himmler's command was responsible for many of the crimes against humanity during World War II...

 (SS), and he had been appointed by the British occupation authorities to the chair for theoretical physics and the directorship of the Max-Planck Institut für Physik
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...

then in Göttingen. Heisenberg wrote the document and convinced the authorities that Jensen had only joined the Party organizations to avoid unnecessary difficulties in academia.

Honors

Honors conferred upon Jensen include:
  • 1947 – Honorary professor 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...

  • 1963 – Nobel Prize in Physics
    Nobel Prize in Physics
    The Nobel Prize in Physics is awarded once a year by the Royal Swedish Academy of Sciences. It is one of the five Nobel Prizes established by the will of Alfred Nobel in 1895 and awarded since 1901; the others are the Nobel Prize in Chemistry, Nobel Prize in Literature, Nobel Peace Prize, and...

  • 1964 – Honorary doctorate from the Technische Universität Hannover (today, the University of Hanover)
  • 1969 – Honorary citizen of Fort Lauderdale, Florida
    Fort Lauderdale, Florida
    Fort Lauderdale is a city in the U.S. state of Florida, on the Atlantic coast. It is the county seat of Broward County. As of the 2010 census, the city had a population of 165,521. It is a principal city of the South Florida metropolitan area, which was home to 5,564,635 people at the 2010...


Internal Reports

The following reports were 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...

. The reports 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...

.
  • 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...

    , Johannes Jensen, Friedrich Knauer
    Friedrich Knauer (chemist)
    Friedrich Wilhelm Karl Knauer was a German physical chemist. During World War II, he worked on the German nuclear energy project, also known as the Uranium Club.-Education:...

    , and Hans Suess
    Hans Suess
    Hans Eduard Suess was an Austrian physical chemist and nuclear physicist. He was a grandson of the Austrian geologist Eduard SuessSuess earned his Ph.D. in chemistry from the University of Vienna in 1935...

     Über die Bremsung, die Diffusion und den Einfang von Neutronen in fester Kohlensäure und über ihren Einfang in Uran G-36 (19 August 1940)
  • Paul Harteck and Johannes Jesnsen Der Thermodiffusionseffekt im Zusammenspiel mit der Konvektion durch mechanisch bewegte Wände und Vergleich mit der Thermosiphonwirkung G-89 (18 February 1941)
  • Johannes Jensen Über die Ultrazentrifugenmethode zur Trennung der Uranisotope G-95 (December 1941)
  • Paul Harteck and Johannes Jensen Gerechnung des Trenneffektes und der Ausbeute verschiedner Zentrifugenanordnungen zur Erhöhung des Wirkungsgrades einer einselnen Zentrifuge G-158 (February 1943)
  • Paul Harteck, Johannes Jensen, and Albert Suhr Über den Zusammenhang zwischen Ausbeute und Trennschärfe bei der Niederdruckkolonne G-159

Books by Jensen

  • Konrad Beyerle
    Konrad Beyerle
    Konrad Beyerle was a German physicist. During World War II, he was in charge of centrifuge research and development at Anschütz & Co. G.m.b.H. He participated in the development of ultracentrifuges for the enrichment of uranium done under the auspices of the German nuclear energy project, also...

    , 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...

    , 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...

    , and Johannes Jensen Über Gaszentrifugen: Anreicherung der Xenon-, Krypton- und der Selen-Isotope nach dem Zentrifugenverfahren (Chemie, 1950); cited in Walker, 1993, p. 278

Selected Literature

  • Otto Haxel
    Otto Haxel
    Otto Haxel was a German nuclear physicist. During World War II, he worked on the German nuclear energy project. After the war, he was on the staff of the Max Planck Institute for Physics in Göttingen...

    , J. Hans D. Jensen, and Hans E. Suess
    Hans Suess
    Hans Eduard Suess was an Austrian physical chemist and nuclear physicist. He was a grandson of the Austrian geologist Eduard SuessSuess earned his Ph.D. in chemistry from the University of Vienna in 1935...

     On the “Magic Numbers” in Nuclear Structure, Phys. Rev. Volume 75, 1766 - 1766 (1949). Institutional affiliations: Haxel: Max-Planck Institut für Physik, Göttingen; Jensen: Institut für theoretische Physik, Heidelberg; and Suess: Inst. für physikalische Chemie, Hamburg. Received 18 April 1949.
  • Helmut Steinwedel, J. Hans D. Jensen, and Peter Jensen
    Peter Herbert Jensen
    Peter Herbert Jensen was a German experimental nuclear physicist. During World War II, he worked on the German nuclear energy project, known as the Uranverein...

    Nuclear Dipole Vibrations, Phys. Rev. Volume 79, Issue 6, 1019 - 1019 (1950). Institutional affiliations: Steinwedel and J. H. D. Jensen - Institut für theoretische Physik, Universität Heidelberg and Peter Jensen - Physikalisches Institut, Universität Freiburg. Received 10 July 1950.
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