After obtaining his doctorate in 1955, Cronin joined the group of
Rodney L. Cool and
Oreste Piccioni at
Brookhaven National Laboratory, where the new
Cosmotron particle accelerator had just been completed. There he started to study
parity violation in the decay of
hyperon particles. During that time he also met
Val Fitch, who brought him to
Princeton University in Fall 1958. After Cosmotron underwent magnet failure, Cronin and the Brookhaven group moved to
Bevatron at the
University of California, Berkeley during the first half of 1958. Cronin and Fitch studied the decays of neutral
K mesons, in which they discovered
CP violation in 1964. This discovery earned the duo the 1980
Nobel Prize in Physics. 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 at
CERN in 1982–83, where he performed an experiment to measure of the lifetime of the
neutral 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 the
University of Utah on a half-time basis to work on
ultra-high-energy cosmic ray physics and to jumpstart the
Pierre Auger Observatory project. His appointment was to last five years, but he left after a year to continue gathering international support for the Observatory with
Alan Watson Cronin is one of the 20 American recipients of the Nobel Prize in Physics to sign a letter addressed to President
George W. Bush in May 2008, urging him to "reverse the damage done to basic science research in the Fiscal Year 2008 Omnibus Appropriations Bill" by requesting additional emergency funding for the
Department of Energy's
Office of Science, the
National Science Foundation, and the
National Institute of Standards and Technology.
Publications • Banner, M.; Cronin, J. W.; Liu, J. K.; & J. E. Pilcher. "Measurement of the Branching Ratio K{sub L} → γ γ / K{sub L} → 3π{sup 0}", Palmer Physical Laboratory,
Princeton University,
United States Department of Energy (through predecessor agency the
Atomic Energy Commission), (August 12, 1968). • Banner, M.; Cronin, J. W.; Liu, J. K.; & J. E. Pilcher. "Measurement of the Branching Ratio K{sub L} → 2π{sup 0} / K{sub L} → 3π{sup 0}", Palmer Physical Laboratory,
Princeton University,
United States Department of Energy (through predecessor agency the
Atomic Energy Commission), (August 14, 1968). • Cronin, J. W.; Frisch, H. J.; Shochet, M. J.; Boymond, J. P.; Mermod, R.; Piroue, P. A.; & R. L. Sumner. "Atomic Number Dependence of Hadron Production at Large Transverse Momentum in 300 GeV Proton—Nucleus Collisions", Enrico Fermi Institute,
University of Chicago, Joseph Henry Laboratories,
Princeton University,
United States Department of Energy (through predecessor agency the
Atomic Energy Commission), National Science Foundation, (July 15, 1974). • Brun, T. O.; Carpenter, J. M.; Krohn, V. E.; Ringo, G. R.; Cronin, J. W.; Dombeck, T. W.; Lynn, J. W.; & S. A. Werner. "Measurement of Ultracold Neutrons Produced by Using Doppler-shifted Bragg Reflection at a Pulsed-neutron Source",
Argonne National Laboratory,
University of Chicago,
University of Maryland, College Park,
University of Missouri,
United States Department of Energy, (1979). • Cronin, J. W.; Deshpande, N. G.; Kane, G. L.; Luth, V. C.; Odian, A. C.; Machacek, M. E.; Paige, F.; Schmidt, M. P.; Slaughter, J.; & G. H. Trilling. "Report of the Working Group on CP Violation and Rare Decays",
University of Chicago,
University of Oregon,
University of Michigan,
Stanford Linear Accelerator Center (SLAC),
Northeastern University,
Brookhaven National Laboratory (BNL),
United States Department of Energy, (October 1984). • Abraham J., Cronin J. W. et al., Observation of suppression of the Flux of Cosmic Rays above 4x10**19 eV., Phys Rev Letters vol 101, p 061101, (2008). ==Personal life==