Condensed Matter Physics | Particle Physics | Astronomy and Astrophysics | Plasma Physics | Theoretical Physics
The programs of instruction and research in the Department of Physics and Astronomy reflect two features which have a long tradition at Hopkins. They are the emphasis on graduate study and research, supplemented by a strong undergraduate program, and the flexibility possible in a department of our size.
The Bloomberg Center for Physics and Astronomy Both undergraduate and graduate courses are designed to provide a central, or core, group of basic subjects at the appropriate levels, which then lead to courses in a variety of specialized topics. As a consequence, students having different backgrounds or different ultimate objectives can select those parts which are most appropriate for them. The selections are made under the guidance of a faculty adviser. The adviser aids the student in making the most efficient use of his or her time and ensures that his or her program contains a reasonable balance among classroom and laboratory, mathematics, seminars, and introduction to research.
At both undergraduate and graduate levels students are encouraged to do as much work as possible in independent work outside the classroom, usually in the form of special projects or independent study. Such work develops early experience in finding one's own way in new areas, and enhances opportunities for contact with faculty, postdoctoral research fellows, and more experienced students (who often provide some of the most effective informal instruction).
With some inevitable and desirable overlapping, current research activities can be divided roughly into five areas: condensed matter physics, high-energy physics, astrophysics, plasma spectroscopy, and theoretical physics. Atomic physics and spectroscopy have had the longest history at Hopkins, originating with Henry A. Rowland in the late 19th century and now continuing in their modern forms: theory of atomic and molecular structure; atomic processes in plasmas and in astrophysics; laser physics; optical spectroscopy of free atoms, molecules, and ions; and measurements of transition probabilities.
The condensed matter physics research in the department is focused on studies of magnetism, critical phenomena, transport properties, pattern formation, nonequilibrium processes, artificially structured solids, low dimensional solids, heavy fermion systems, low temperature physics, neutron diffusion, high Tc superconductivity, complex fluids, and disordered systems. In recent years, the program has involved studies of nanostructured materials, magnetic and superconducting multilayers, granular metals and metal superlattices, quasi 1-dimensional magnetic systems, heavy fermion systems, and the families of new high Tc oxide superconductors. Techniques used in these studies involve LEED and Auger electron spectroscopy, synchrotron x-ray scattering, He3 -He4 dilution refrigeration, neutron diffraction, magnetotransport measurements, magnetic susceptibility, vibrating sample magnetometry, SQUID magnetometry, ferromagnetic resonance, synchrotron radiation, X-ray and electron diffraction spectroscopy, scanning electron microscopy, and transmission electron microscopy. A molecular beam epitaxy system and high-rate sputtering systems, in addition to single-crystal growth are used for sample fabrication.
The Materials Research Science and Engineering Center (MRSEC), sponsored by the National Science Foundation, focuses in the area of nanostructured materials. A wide range of novel properties, unattainable in bulk materials, are now being achieved through the manipulation of the nanostructure. The research effort includes synthesis and processing, structural characterization, physical property measurements, theoretical modeling, and prototype device fabrication and applications.
The Johns Hopkins-Princeton Institute for Quantum Matter (IQM), funded by the Department of Energy, seeks to expose and understand materials dominated by quantum coherence and quantum correlations. The institute combines chemical synthesis, advanced spectroscopy, and theoretical analysis for new fundamental understanding of interacting quantum particles and to discover materials with a potential for applications in the energy and information technology sectors.
The high-energy physics group engages in experimental programs to investigate the behavior of elementary particles in strong, electromagnetic and weak interactions. These experiments are generally conducted at the National Laboratories within the United States, (Brookhaven, SLAC, Fermilab and Los Alamos) which have particle accelerators, or at similar facilities in other parts of the world (CERN, KEK). The experimental techniques include the use of a wide variety of sophisticated particle detectors such as time projection chambers, proportional and drift chambers, electromagnetic calorimeters, Cerenkov counters, silicon detectors, and scintillation counters.
The primary current experiment studies anti-proton interactions and is at the Fermilab Tevatron collider. The Tevatron collider is the highest energy laboratory in the world for the study of the interactions of elementary particles. The main emphasis of the Johns Hopkins research within this experiment is the study of heavy quarks and investigations of phenomena beyond the Standard Model of particle physics. For the bottom quark this includes measurements of the masses, lifetimes and decay modes of B mesons and baryons, for investigations of b mixing and search for CP violation in b decays. For the top quark the goal is to establish firmly its mass and decay and production properties. The research on physics beyond the Standard Model aims at the many hypothesized particles that are central to our theoretical understanding of the origin of mass.
To push particle physics to an entirely new region, a new collider and new detectors are being constructed at CERN for the next century. International resources are pooled to construct the LHC (Large Hadron Collider) to reach 14 TeV in proton-proton collisions. Hopkins is part of the CMS (Compact Muon Solenoid) Collaboration to build the detector to search for new phenomena and to elucidate Electroweak Symmetry Breaking and the origin of mass.
Research in theoretical physics covers a wide range of topics. In particle physics, research centers on the elementary particles and their interactions, such as the properties of field theories and string theories and the implications of particle physics for astrophysics and cosmology. Much attention is focused on issues relevant to the physics of the contemporary high energy experimental program, including tests of the Standard Model and its extensions, such as supersymmetry, dynamical symmetry breaking and extra spatial dimensions. Other topics of current interest include CP violation and the phenomenology of heavy quark systems.
Activities in condensed matter theory center on the study of disordered systems, nonequilibrium dynamics, high-Tc superconductors, quantum critical phenomena, magnetotransport, superfluidity, and electrons in high magnetic fields. Many of these theoretical activities are closely correlated with those of the experimental groups. Work in atomic physics includes electronic transitions involving lanthanide ions in crystals and solutions, the use of orthogonal operators for analyzing the energy levels of free atoms, and the use of group theory in atomic structure and icosahedral systems.
The research topics pursued within the astrophysics group cover the entire gamut of the field, from cosmology to solar system studies. Theoretical work, observational work (from both ground-based and space-based observatories), and new-instrument development can all be found here. A more expanded description of programs currently under way can be found at Astrophysics Research.
Intellectual life in the Baltimore astrophysical community is greatly enhanced by the close ties that exist between the Department of Physics and Astronomy and the Space Telescope Science Institute, located immediately across San Martin Drive. There is tremendous interaction between the people of the two groups in venues ranging from lunch-table conversations to seminars to collaborative research projects to shared facilities.
The Center for Astrophysical Sciences is a special unit within the Department of Physics and Astronomy that provides administrative, managerial, and technical support to astrophysical research at JHU.
The plasma spectroscopy program has grown out of the astrophysics research. Under grants from the Department of Energy, the Plasma spectroscopy Group develops Far Ultraviolet and soft X-ray spectroscopic instrumentation for the diagnostic of Magnetic Fusion Energy (MFE) experiments and applies it to the study of high temperature plasmas. The research covers topics central to the fusion plasma physics, like magneto-hydrodynamic stability, particle and energy transport, as well as atomic physics topics, like the spectroscopy of the highly ionized species relevant to these plasmas.
Complex diagnostic systems, integrating state-of-the-art detectors and X-ray optics, have been developed for leading MFE experiments, like the National Spherical Torus Experiment (NSTX) at the Princeton Plasma Physics Laboratory and the C-Mod tokamak at MIT. The sperical torus is a new and promising path toward economical fusion energy, relying on the achievement of near unity beta (plasma pressure to magnetic pressure ratio), in a tight aspect-ratio configuration. The Johns Hopkins systems enable experiments that cannot be performed by conventional instrumentation, like imaging of peripheral magnetic islands, or determination of the hot plasma resistivity. The Plasma Spectroscopy Group has also an active role in the National NSTX Research Team, which has the mission of advancing the sperical torus concept toward its assessment as a viable fusion rector.
Recent research topics of the group include the development of 2-D and 3-D ultrafast imaging techniques in the soft X-ray range, for the study of localized MHD perturbations, like the neo-classical tearing modes. Such perturbations seem to have a profound effect on the stability and confinement properties of high beta plasmas. A new research subject is also the study of turbulence in fusion plasma using focusing, soft X-ray telescopes. Such instruments have been first developed in astrophysics.
The atomic physics packages necessary for retrieving the plasma parameters from the spectroscopic data are developed in collaboration with researchers at the Lawrence Livermore National Laboratory and benchmarked on various fusion experiments in the U.S. and Europe. Recent international collaborations also include the development of a 2-D Far Ultraviolet imaging system for the measurement of local particle transport in the Large Helical Device, the largest fusion experiment in Japan.