Research Associate, Lawrence Berkelely Lab 1962-64; NATO Postdoctoral Fellow 1964-65 at CERN; Assistant-Associate Professor, MIT, 1965-73; Professor, Virginia Tech, 1973-80 (Department Head 1973-77); Physical Science Officer, U.S. Arms Control and Disarmament Agency 1978-90; Professor of Physics, Southern Methodist University 1990-present (Chair, 1990-95); Senior Advisor on International Coordination, Superconducting Super Collider Laboratory 1991-93; White house Science Office, Senior Policy Analyst, 2000-2002; U.S. Representative to NATO Science Committee 2000-present (about 3 meetings/year)
Research is at the border between elementary particle theory, on the one hand, and astrophysics and cosmology on the other.
Some past work included the first limits on the lifetimes of unstable neutrinos as a function of their mass (late 1970's and the first calculations of energy loss from main sequence stars, red giants and supernovae due to "axion" (still a finalist in the dark matter candidate race) emission (late 1070's and early 1980's)
It included work on two dark horse dark matter candidates, strongly interacting massive particles (SIMPS) and shadow matter (late 90's into early this century).
Recent work has focused on strange quark matter (SQM). SQM might be the lowest energy state of baryonic matter: it would be made of up, down and strange quarks, whereas familiar matter is made of just up and down which condense into protons and neutrons. SQM would have nuclear density (a nugget of ton mass would be the size of a blood cell). It might be made primordially. If stable, it almost certainly is the material of "neutron stars." In passing through a body it would leave behind seismic waves. We searched a million seismic reports reports to the U.S. Geological Survey looking for the arrival pattern of a line source and set a limit on SQM nuggets.
Since the President's initiative, I have increasingly focused on using the moon, instead of the Earth, to detect SQM nuggets. The moon, although smaller is seismically about a millionth as noisy as the Earth and hence is sensitive to passages of nuggets in the kilogram range, rather than the ton range as with the Earth
A paper has been written, and accepted, subject to modest changes, setting a limit on nuggets from data collected by Apollo mission seismometers. A proposal for theory study has been submitted to the Astrophysics Theory Program. A second proposal, which includes study of a new seismometer design, has been submitted with people from JPL who have become interested in the SQM search.
S.B. 1958, MIT, Physics
Ph.D. 1962 University of Maryland, Elementary Particle Theory (Pion Production in Pion-Pion Scattering)
42. "Cosmological Upper Bound on Heavy Neutrino Lifetimes," with D. A. Dicus and E. W. Kolb, Phys. Rev. Lett. 39, 168 (1977); 44 and 45 are follow on work.
46. "Astrophysical Bounds on the Masses of Axion and Higgs Particles," with Dicus, Kolb, and R. V. Wagoner, Phys. Rev. D18, 1829 (1978); 53 extends to light axion.
58. "Two and Three Body Contributions to Cosmological Monopole Annihilation," with D. A. Dicus and D. M. Page, Phys. Rev. D26, 1306 (1982).
62. "Finite Temperature Corrections to the van der Waals Potential," L. Chiu, D. Dicus, E. Kolb, B. Joseph, and M. Turner, Phys. Rev. A31, 1458 (1985).
64. "Bounds on Dark Matter in Solar Orbit," with J. D. Anderson, E. L. Lau, A. H. Taylor, D. A. Dicus, and D. C. Teplitz, the Astrophysical Journal 342, 539 (1989).
67. "Improved Bounds on Non-luminous Matter in Solar Orbit," with J.D. Anderson et al (JPL), D.A. Dicus, and D.C. Rosenbaum, Astrophysical Journal 448, 885 (1995).
68. "Whole Earth Seismic Telescope", with E. T. Herrin, in "Clusters, Lensing and the Future of the Universe," V. Trimble and A. Reisenegger, Eds, ASP Conference Series, Vol. 88, (1996).
70. "New Supernova Constraints on Sterile Neutrino Production" with E. W. Kolb and R. N. Mohapatra, Phys. Rev. Letters, 77, 3066 (1996).
71. "Structures in the Mirror Universe," with R. N. Mohapatra, Astrophysical Journal 478, 29 (1997).
72. "Kuiper Belt Constraint from Pioneer 10," with J. D. Anderson, E. L. Lau, D. C. Rosenbaum, and K. Scherer, Icarus 131, 167 (1998).
75. "Supernova Constraints on a Superlight Gravitino," with D. A. Dicus and R. N. Mohapatra, Phys. Rev., 52, 518 1998.
76. "Primordial Nucleosynthesis Constraint on Massive, Stable, Strongly Interacting Particles," with R. N. Mohapatra, Phys. Rev. Lett . 81, 3079 (1998).
77. "Infrared Kuiper Belt Constraints," with J.D. Anderson, D. Rosenbaum, R. Scalise, A. Stern, and P.Wentzler, Astrophysical Journal, 516, 425 (1999).
79. "Searching for SIMPs", with R. N. Mohapatra, F. Olness, and R. Stroynowski, Phys. Rev. D60, 115013 (1999).
80. "Mirror Matter MACHOs," with R. N. Mohapatra, Physics Letters B462, 302 (1999).
81 "TeV Scale Quantum Gravity and Mirror Supernovae as Sources of Gamma Ray Bursts", with R. N. Mohapatra and S. Nussinov, Astroparticle Physics 13, 295 (2000).
82. "Mirror Matter Dark Matter and the Core Density of Galaxies," with R.N. Mohapatra, Phys. Rev. D62, 06350 (2000); Astro-ph/0001362
86. "Astrophysical Implications of Limits on Strongly Interacting Massive Particles," with D. Javorsek, and E. Fischbach, Ap.J (published).
88. "Competition Between Gravitational and Scalar Field Radiation," with D. Kazanas, ApJ 602, 111 (2004)
89. "Neutrino Mass, Dark Matter, and Inflation," with D. Kazanas, R. Mohapatra, and S. Nasri, hep-ph/0403291, published in Phys. Rev.
90. "Seismic Search for Strange Quark Nuggets," with E. T. Herrin and D. C. Rosenbaum, Astro-ph/0505584, being revised for Physical Review