Cronin and co-researcherVal Logsdon Fitch were awarded the 1980Nobel Prize in Physics for a 1964 experiment that proved that certain subatomic reactions do not adhere to fundamental symmetry principles. Specifically, they proved, by examining the decay ofkaons, that a reaction run in reverse does not merely retrace the path of the original reaction, which showed that the interactions ofsubatomic particles are not invariant under time reversal. Thus the phenomenon ofCP violation was discovered.[4][5][6][7][excessive citations]
Cronin received theErnest Orlando Lawrence Award in 1976 for major experimental contributions to particle physics including fundamental work on weak interactions culminating in the discovery of asymmetry under time reversal. In 1999, he was awarded theNational Medal of Science.[8]
James Cronin was born inChicago on September 29, 1931. His father, James Farley Cronin, was a graduate student of classical languages at theUniversity of Chicago. After his father had obtained his doctorate the family first moved to Alabama, and later in 1939 toDallas,Texas, where his father became a professor of Latin and Greek atSouthern Methodist University. After high school Cronin stayed in Dallas and obtained an undergraduate degree at SMU in physics and mathematics in 1951.[10] He is of Irish descent, with his Irish ancestors immigrating from County Cork, Ireland.[11]
After the discovery, Cronin spent a year inFrance at theCentre d'Études Nucléaires atSaclay. After returning to Princeton he continued studying the neutral CP violating decay modes of the long-lived neutral K meson. In 1971, he moved back to the University of Chicago to become a full professor. This was attractive for him because of a new 400 GeV particle accelerator being built at nearbyFermilab.[10] He received theQuantrell Award.[12]
When he moved to Chicago, he began a long series of experiments on particle production at high transverse momentum. With physicist Pierre Piroue and colleagues we learned about many things. These are summarized in Physical Review D, vol 19, page 764 (1977). Following these experiments Cronin took a sabbatical atCERN in 1982–83, where he performed an experiment to measure of the lifetime of theneutral pion (Physics Letters vol 158 B page 81, 1985). He then switched to the study of cosmic rays. The first was a series of measurements looking for point sources of cosmic rays. No sources were found. A summary of the measurements was published in Physical Review D vol 55 page 1714 (1997). In 1998 he joined the faculty at theUniversity of Utah on a half-time basis to work onultra-high-energy cosmic ray physics and to jumpstart thePierre Auger Observatory project.[13] His appointment was to last five years, but he left after a year to continue gathering international support for the Observatory withAlan Watson[3] and Murat Boratav.[14]
While in graduate school he also met his wife, Annette Martin, whom he married in 1954.[10] She was the Director of Special Events at the University of Chicago.[16] They have three children: two daughters, Cathryn (b. 1955) and Emily (b. 1959), and a son, Daniel (b. 1971).[10] In June 2005 Annette Martin died of complications of Parkinson's disease. She was 71.[16]
In November 2006 he married Carol Champlin.
In May 2011 his daughter Cathryn Cranston died of leukemia at age 54.
Cronin died on August 25, 2016, at the age of 84.[3][2][17][18]
