جيمس كرونين

جيمس كرونين
James Cronin
وُلِدَ	29 سبتمبر 1931 شيكاجو، إلينوي، الولايات المتحدة
توفي	أغسطس 25, 2016(2016-08-25) (aged 84) سانت پول، مينسوتا، الولايات المتحدة
الجنسية	أمريكي
المدرسة الأم	الجامعة المثودية الجنوبية جامعة شيكاغو (Ph.D.)
اللقب	الفيزياء الذرية
الجوائز	E. O. Lawrence Award (1976) جائزة نوبل في الفيزياء (1980) John Price Wetherill Medal National Medal of Science
السيرة العلمية
المجالات	الفيزياء
الهيئات	جامعة شيكاغو

جيمس واطسون كرونين James Cronin (و. 2 سبتمبر 1931)، هو عالم فيزياء أمريكي حاز على جائزة نوبل للفيزياء عام 1980 عن تجربة أجراها عام 1964 أثبتت انكسار مبدأ التناظر خلال بعض التفاعلات التي تجري بين الجسيمات الأولية. وقد شاركه في الجائزة زميله ڤال ڤيتش.

ولد كرونين بمدينة شيكاغو بولاية إلينوي. اكتشف مع زميله ڤال ڤيتش أن تحلل ال ك-ميزون لا يسري عكسيا بنفس الطريقة، مما يبين أن التفاعلات بين الجسيمات الاولية تتغير مع الزمن، وبالتالي اكتشاف انكسار المجانسة CP violation. يعمل كرونين استاذا غير متفرغ بجامعة شيكاغو وهو المتحدث الرسمي لمرصد پيير أوجي.

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 الأبحاث والسيرة

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.

After the discovery, Cronin spent a year in France at the Centre d'Études Nucléaires at Saclay. 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 nearby Fermilab.

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 and Murat Boratav.

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 of 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).

 وصلات خارجية

• Cronin's Nobel lecture on CP Symmetry Violation
• James Watson Cronin at Nobel-winners.com
• James Cronin at nobelprize.org
• the discovery of violations of fundamental symmetry principles in the decay of neutral K-mesons.
• Short biography at the University of Chicago