William R. MolzonProfessor, Physics & Astronomy |
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Research Interests |
Experimental Particle Physics | |
| URL | www.physics.uci.edu/faculty/molzon.html | |
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Research Abstract |
Professor Molzon received his B.S. from Caltech and his Ph.D. from the University of Chicago in 1979. He held a postdoctoral position at CERN in Geneva, Switzerland, before joining the Physics Department at the University of Pennsylvania. He moved to UCI in 1988. He is a recipient of a Sloan Fellowship and a Department of Energy Outstanding Junior Investigator Award. Professor Molzon has worked in various areas of experimental particle physics. One group of experiments concentrated on elucidating the interactions between fundamental particles (quarks and gluons). It includes the first experiment to show that high energy photons are produced directly in the scattering of quarks and gluons contained within protons. Another experiment studied the production of "jets" of high energy particles, which we associate with the scattering of quarks and gluons, resulting in a collimated group of physical particles which carry the momentum of the scattered constituent. More recently, Professor Molzon has tested the conservation of additive quantum numbers associated with electron and muon type leptons. An outstanding puzzle in our understanding of particle physics is the existence of three "families" of quarks and leptons. They are distinguished by mass and by an additive quantum number; in the case of leptons this quantum number is apparently conserved exactly. These conservation laws are not understood in any fundamental sense, and this research is producing more stringent tests of their validity. The specific tests involve a search for the decay of a K_L (an unstable meson containing s and d type quarks) into mu+ and e-. Observation of such a decay would be primafacie evidence for non- conservation of muon-and electronlepton number. The experiments are being done at Brookhaven National Laboratory, which has the world's most intense beam of neutral kaons, in collaboration with physicists from Stanford, the University of Texas at Austin, and the College of William and Mary. Professor Molzon's group has built high precision drift chambers, sophisticated electronics to process the electrical signals generated in the chambers, and custom computer memory boards to allow data from the experiment to be analyzed in real time. In addition to this test of electron and muonnumber conservation, Professor Molzon's experiments have measured with high precision the decay rate for K_L to mu+mu-. This decay mode is highly suppressed, and proceeds by second order weak interactions. Given sufficiently precise measurements, one can infer the mass and coupling of the as yet unseen top quark. This series of experiments is continuing, with a newly approved experiment intended to improve the experimental sensitivity by a factor of 20. Professor Molzon has taught a variety of mostly undergraduate courses. He serves as graduate advisor, and has instituted a series of seminars for first year graduate students to help familiarize them with the research programs of the faculty. |
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| Publications |
Improved Upper Limit on the Branching Ratio B(K_L -> mu e), K. Arisaka et al., Phys. Rev. Let. 70, 1049 (1993). |
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| Higher-statistics Measurement of the Branching Ratio for the Decay K_L -> mu mu ,A. Heinson et al., Phys. Rev. D44, R1 (1991). | ||
| New Experimental Limits on K_L -> mu e and K_L -> ee Branching Ratios, Phys. Rev. D40, 1712 (1989). | ||
| Link to this profile | http://www.faculty.uci.edu/profile.cfm?faculty_id=2062 | |
| Last updated | 04/01/2002 | |