Question: Karl Paley Cohen workd within a group that included an American physicist who won the Nobel Price in Physics for his discovery of what?

Context paragraphs:
Daniel C. Tsui: Daniel Chee Tsui (, born February 28, 1939, Henan Province, China) is a Chinese-born American physicist whose areas of research included electrical properties of thin films and microstructures of semiconductors and solid-state physics.  He was previously the Arthur LeGrand Doty Professor of Electrical Engineering at Princeton University and adjunct senior research scientist in the Department of Physics at Columbia University, where he was a visiting professor from 2006 to 2008.  Currently, he is a research professor at Boston University.  In 1998, along with Horst L. Störmer of Columbia and Robert Laughlin of Stanford, Tsui was awarded the Nobel Prize in Physics for his contributions to the discovery of the fractional quantum Hall effect.

Karl P. Cohen: Karl Paley Cohen (February 5, 1913 – April 6, 2012) was a physical chemist who became a mathematical physicist and helped usher in the age of nuclear energy and reactor development.  He began his career in 1937 making scientific advances in uranium enrichment (isotope separation) as research assistant to Harold Urey, whose discovery of deuterium–the heavy isotope of hydrogen– earned him the 1934 Nobel Prize.  Cohen worked within the Columbia group of physicists that included Harold Urey, Enrico Fermi, Leo Szilard, Isidor Isaac Rabi, John R. Dunning, Eugene T. Booth, A. Von Gross and others)–all pioneers of nuclear energy.

John L. Hall: John Lewis "Jan" Hall (born August 21, 1934) is an American physicist, and Nobel laureate in physics.  He shared one fourth of the 2005 Nobel Prize in Physics with Theodor W. Hänsch and Roy Glauber for his work in precision spectroscopy.

Yoichiro Nambu: Yoichiro Nambu (南部 陽一郎 , Nambu Yōichirō , 18 January 1921 – 5 July 2015) was a Japanese-born American physicist, a professor at the University of Chicago.  Known for his contributions to the field of theoretical physics, he was awarded half of the Nobel Prize in Physics in 2008 for the discovery in 1960 of the mechanism of spontaneous broken symmetry in subatomic physics, related at first to the strong interaction's chiral symmetry and later to the electroweak interaction and Higgs mechanism.  The other half was split equally between Makoto Kobayashi and Toshihide Maskawa "for the discovery of the origin of the broken symmetry which predicts the existence of at least three families of quarks in nature."

Isidor Isaac Rabi: Isidor Isaac Rabi ( ; born Israel Isaac Rabi, 29 July 1898 – 11 January 1988) was an American physicist who won the Nobel Prize in Physics in 1944 for his discovery of nuclear magnetic resonance, which is used in magnetic resonance imaging.  He was also one of the first scientists in the United States to work on the cavity magnetron, which is used in microwave radar and microwave ovens.

William Shockley: William Bradford Shockley Jr. ( ; February 13, 1910 – August 12, 1989) was an American physicist and inventor.  Shockley was the manager of a research group at Bell Labs that included John Bardeen and Walter Brattain.  The three scientists were jointly awarded the 1956 Nobel Prize in Physics for "their researches on semiconductors and their discovery of the transistor effect."

Clinton Davisson: Clinton Joseph Davisson (October 22, 1881 – February 1, 1958), was an American physicist who won the 1937 Nobel Prize in Physics for his discovery of electron diffraction in the famous Davisson-Germer experiment.  Davisson shared the Nobel Prize with George Paget Thomson, who independently discovered electron diffraction at about the same time as Davisson.

Arthur Compton: Arthur Holly Compton (September 10, 1892 – March 15, 1962) was an American physicist who won the Nobel Prize in Physics in 1927 for his 1923 discovery of the Compton effect, which demonstrated the particle nature of electromagnetic radiation.  It was a sensational discovery at the time: the wave nature of light had been well-demonstrated, but the idea that light had both wave and particle properties was not easily accepted.  He is also known for his leadership of the Manhattan Project's Metallurgical Laboratory, and served as Chancellor of Washington University in St. Louis from 1945 to 1953.

Murray Gell-Mann: Murray Gell-Mann ( ; born September 15, 1929) is an American physicist who received the 1969 Nobel Prize in physics for his work on the theory of elementary particles.  He is the Robert Andrews Millikan Professor of Theoretical Physics Emeritus at the California Institute of Technology, a Distinguished Fellow and co-founder of the Santa Fe Institute, Professor in the Physics and Astronomy Department of the University of New Mexico, and the Presidential Professor of Physics and Medicine at the University of Southern California.

Russell Alan Hulse: Russell Alan Hulse (born November 28, 1950) is an American physicist and winner of the Nobel Prize in Physics, shared with his thesis advisor Joseph Hooton Taylor Jr., ""for the discovery of a new type of pulsar, a discovery that has opened up new possibilities for the study of gravitation"".  He was a specialist in the pulsar studies and gravitational waves.

Supporting paragraphs: Karl P. Cohen Isidor Isaac Rabi
Answer: nuclear magnetic resonance