Question: Cooper pairs were first described by an American physicist born in what year?
Context: Leon N Cooper (born February 28, 1930) is an American physicist and Nobel Prize laureate, who with John Bardeen and John Robert Schrieffer, developed the BCS theory of superconductivity.  He is also the namesake of the Cooper pair and co-developer of the BCM theory of synaptic plasticity. William Stanley Jr. (November 28, 1858 – May 14, 1916) was an American physicist born in Brooklyn, New York.  In his career, he obtained 129 patents covering a variety of electric devices.  In 1913, he also patented an all-steel vacuum bottle, and formed the Stanley Bottle Company. In condensed matter physics, a Cooper pair or BCS pair is a pair of electrons (or other fermions) bound together at low temperatures in a certain manner first described in 1956 by American physicist Leon Cooper.  Cooper showed that an arbitrarily small attraction between electrons in a metal can cause a paired state of electrons to have a lower energy than the Fermi energy, which implies that the pair is bound.  In conventional superconductors, this attraction is due to the electron–phonon interaction.  The Cooper pair state is responsible for superconductivity, as described in the BCS theory developed by John Bardeen, Leon Cooper, and John Schrieffer for which they shared the 1972 Nobel Prize. Mohammad Sajjad "Saj" Alam (born 5 January 1947) is an American physicist born in British India (Pakistan after 1947, and Bangladesh after 1971).  His work has focused on particle physics and computational physics.  He has played a significant role in several major particle physics experiments (the Mark II, CLEO, GEM, BaBar, ATLAS collaborations) that have led to new discoveries in the area of high-energy particle physics. BCS theory or Bardeen–Cooper–Schrieffer theory (named after John Bardeen, Leon Cooper, and John Robert Schrieffer) is the first microscopic theory of superconductivity since Heike Kamerlingh Onnes's 1911 discovery.  The theory describes superconductivity as a microscopic effect caused by a condensation of Cooper pairs into a boson-like state.  The theory is also used in nuclear physics to describe the pairing interaction between nucleons in an atomic nucleus. Curtis Judson Humphreys (17 February 1898 – November 1986) was an American physicist born in Alliance, Ohio, USA.  He was chief of the Radiometry Section of the U.S. Navy during the 1940s.  He is famous for discovering the Humphreys series of the hydrogen atom. Keith Schwab (born May 18, 1968) is an American physicist born in St. Louis, Missouri.  His contributions are in the areas of nanoscience, ultra-low temperature physics, and quantum effects.  He co-directs the Kavli Nanoscience Institute at Caltech with Prof. Nai-Chang Yeh. In condensed matter physics, the resonating valence bond theory (RVB) is a theoretical model that attempts to describe high temperature superconductivity, and in particular the superconductivity in cuprate compounds.  It was first proposed by an American physicist P. W. Anderson and Indian theoretical physicist Ganapathy Baskaran in 1987.  The theory states that in copper oxide lattices, electrons from neighboring copper atoms interact to form a valence bond, which locks them in place.  However, with doping, these electrons can act as mobile Cooper pairs and are able to superconduct.  Anderson observed in his 1987 paper that the origins of superconductivity in doped cuprates was in the Mott insulator nature of crystalline copper oxide.  RVB builds on the Hubbard and t-J models used in the study of strongly correlated materials. Dr. Praveen Chaudhari (November 30, 1937 – January 12, 2010) was an Indian American physicist born in Ludhiana, India, who migrated to the United States in 1961 and contributed to the field of material physics. David B. Kaplan is an American physicist born in 1958.  He was Director of the Institute for Nuclear Theory at the University of Washington during the period 2006-2016 and is now a Senior Fellow there.
Answer: 1930