Research

Solar-Terrestrial Theory Group| Theoretical Plasma and Space Physics| Cosmic Ray Group|

High Energy Astrophysics| Condensed Matter | Experimental Nuclear and Particle Physics |

Nuclear and High Energy Theory | Medical Imaging | Physics Education Research

Research Opportunities at UNH

The Physics Department at UNH offers excellent research opportunities to both our graduate and undergraduate students. An overview of undergraduate research at UNH and specific examples of undergraduate students involved in research are found at the Undergraduate Research page.

For a listing of recent publications by Physics Department faculty and students, please go to Physics Department Publications

Solar-Terrestrial Theory Group

Solar-Terrestrial

This group concentrates on theoretical studies related to the sun, with emphasis on the solar corona, solar flares and coronal mass ejections, the solar wind, cosmic rays, and the heliosphere. Major research areas include particle acceleration and transport throughout the heliosphere, and the heating and acceleration of the solar plasma. The group seeks to understand basic plasma physical processes such as magnetic reconnection, the nonlinear evolution of waves, and magnetohydrodynamic turbulence, and the roles those processes play in observed solar phenomena.

Professors: Marty Lee, Benjamin Chandran, Terry Forbes, Phil Isenberg, Bernie Vasquez, Sergei Markovskii and Joe Hollweg (emeritus)

Theoretical Plasma and Space Physics

The theoretical plasma physics group uses analytical and numerical methods to address a wide spectrum of problems of relevance to space, astrophysical, and laboratory plasmas. Bhattacharjee is involved in fundamental research on magnetic reconnection with applications to magnetospheric substorms, solar coronal heating and flares, and magnetic island dynamics in fusion plasmas. He is also involved in turbulence research, and in particular, the problems of energy and density fluctuation spectra in the magnetized interstellar medium and solar wind, and vorticity intensification and singularity formation in ordinary fluids. Chen is studying magnetic reconnection in simulations and magnetospheric data, particle acceleration at reconnection sites, and electrostatic structures. Kaufmann has created three-dimensional data-based models of the plasma sheet (based on data from the Geotail satellite). The topics that are being studied now using these models involve thermodynamics (changes in the content, entropy, magnetization, several adiabatic invariants, and fast flows) and electric currents (magnetization, guiding center, and parallel currents) in this portion of the Earth's geomagnetic tail. Other topics to be studied involve reconnection, substorms, and energy transport. Raeder's research focuses on the global modeling of Earth's magnetosphere-ionosphere-atmosphere system to study the interaction of the solar wind with Earth's space environment. Besides the basic research aspect, that is, understanding the plasma interaction of planetary magnetospheres, this research has practical applications in the area of space weather effects, that is, harmful effects on technological systems, for example, satellites or power grids.

Professors: Amitava Bhattacharjee, Li Jen Chen, Dick Kaufmann, Jimmy Raeder and Kai Germaschewski

Cosmic Ray Group

The cosmic ray group studies energetic particle radiation in space. The particles of interest to us typically have energies in the range ~0.5 MeV to ~20,000 MeV. There are four sources for these high-energy particles: Galactic cosmic rays, the anomalous component, Solar energetic particles and planetary energetic particles. We study all these sources.

We are an experimental group and our instruments include ground-based neutron monitors and space based instruments on the Ulysses and IMP-8 spacecraft. The space-based instruments detect the energetic particles directly, while the neutron monitors detect secondary baryons produced by particles (mostly Galactic cosmic rays) colliding with nuclei in the atmosphere. We also have an active instrument development program with the goal of producing innovative new instruments for future space flight opportunities.

Professors: Jim Connell, Bruce McKibben and Cliff Lopate

High Energy Astrophysics

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This group has carried out studies from high altitude balloons and from spacecraft. The principal UNH satellite based studies were carried aboard the Solar Maximum Mission and the Gamma Ray Observatory satellites. The UNH detectors measured emissions from the sun and from a number of galactic sources. Galactic gamma rays often are produced by the most dynamic and highest temperature plasmas in the universe. Efforts have concentrated on identifying and mapping sources, on studying the time dependence of emissions, on determining the spectrum and line structure of the sources, and on studies of the cosmic diffuse background radiation. The student designed CATSAT satellite, which is described separately below, is built to study gamma ray bursts.

Professors: Ed Chupp (emeritus), Jim Ryan, Mark McConnell

Experimental Space Plasma Group
Space Plasma

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This is a collaboration of researchers working on several distinct Space Science projects. The 14 Professors, Research Professors, and Research Scientists in this program are using data from UNH instruments carried on the ACE, AMPTE, Cluster, Equator-S, FAST, IBEX, Polar, STEREO, SOHO, and Wind satellites. In addition, UNH researchers are actively involved in the development and building of the Magnetosphere MultiScale (MMS) and Radiation Belt Storm Probe (RBSP) missions. Data also are taken by instruments on sounding rockets and by ground based detectors. Most of the UNH experiments have concentrated on the measurement of electrons and of ions with various charges and masses. These data are analyzed in conjunction with magnetometer and electric field data measured by detectors developed either at UNH or at other collaborating institutions. The regions studied range from the solar wind or interplanetary plasma to the Earth's bow shock, magnetosheath, magnetosphere, and auroral regions.

Professors: Roy Torbert, Eberhard Mobius, Lynn Kistler, Toni Galvin, Charlie Farrugia, Harald Kucharek, Chuck Smith and Marc Lessard

 

 

Condensed Matter

UNH has an emerging program in condensed matter physics that involves three exciting areas of research. The first is the study of Atomic Clusters, tiny aggregates comprising from just two or three to thousands of atoms. These largely unexplored systems offer a remarkable example of interdisciplinary interest, since they are relevant to topics as diverse as molecular physics, catalysis, astrophysical chemistry, crystal growth, solid state physics, and materials science. Fullerenes, also called "buckyballs", are the best known representative of atomic clusters. These hollow, all-carbon clusters are chemically stable under ambient conditions, but they feature several competing reaction channels when highly excited by a laser pulse. Moreover, it is possible to implant atoms into the fullerene cage (Professor Olof Echt).

The second area of research in condensed matter physics is experimental Surface Science. The field is driven by the quest for smaller, faster, brighter and longer-lived in the development of electronic, magnetic, and photonic devices resulting in ever greater miniaturization and growing importance of surfaces, interfaces, and thin films as surface-to-volume ratios increase. The physical properties of low-dimensional structures are in general very different from those of bulk matter. If at least one dimension of such structures is small enough that quantum-mechanical effects become important, their electronic, magnetic, and catalytic behavior is particularly fascinating. Our research involves the study of the interplay of electronic, vibrational and structural surface properties at the atomic scale. Specific measurement techniques in ultra-high vacuum include atomic resolution scanning tunneling microscopy (STM) and photoelectron spectroscopy utilizing synchrotron radiation sources. Currently two advanced Ph.D. students in our group are investigating different aspects of the dynamics of self-assembly of nanoscale structures at strained metallic surfaces by STM (Professor Karsten Pohl).

The third area of research in condensed matter physics is the science of Thin Films. We use evaporation, pulsed laser deposition and ion beam assisted sputter deposition to control the growth environment in novel ways. One example is to provide low energy ion bombardment at a non-normal angle of incidence during deposition to induce in-plane alignment of the microstructure of thin films. Such highly oriented polycrystalline thin films can be used as templates for subsequent growth of new materials. We are particularly interested in combining different kinds of materials on short length scales to create nanocomposites with unusual properties (Professor James Harper).

The theoretical condensed matter group is developing analytical and computational tools to study the electronic structures and optical properties of metal and semiconductor nanostructures. Current research lies in the areas of spintronics and quantum information. Topics include spin-spin interaction in magnetic semiconductors, spin manipulation with external fields, optical properties of magnetic semiconductors and spin-dependent electronic structure near interfaces. Other research interests include interplay between disorder and quantum coherence in high-temperature superconductors and vortex dynamics in Bose-Einstein condensation.

Professors: Olof Echt, Jim Harper (affiliate), Karsten Pohl, Jian-Ming Tang

Experimental Nuclear and Particle Physics

The CLAS Detector

The Department of Physics has an active and widely recognized program in Nuclear and Particle Physics. The majority of our present experimental programs is focused at Jefferson Laboratory in Newport News, Virginia, which is an international center for nuclear physics research. In addition, we are engaged in a program of fundamental physics using cold neutrons at Los Alamos and Oak Ridge national Laboratories.

At Jefferson Lab, we are embarking on an ambitious experimental program that will search for the "heavy photon", a partner to the photon and a dark matter candidate. The heavy photon search (HPS) experiment will use an uncommonly small, almost table top, detector at the intensity frontier in particle physics.

We also lead a program at Jefferson Lab for studying the structure of the nucleon through spin-dependent observables.  As part of this effort, we are analyzing the data from the recently completed g2p experiment, which should shed light on the so called `Proton Radius Puzzle'.  Our group is is also at the forefront of an exciting new effort to measure Tensor Spin Observables using a novel tensor polarized target.

At Los Alamos and Oak Ridge we are collaborating on experiments using newly available beams of very slow neutrons to study the properties of the neutron itself. These experiments are sensitive to the fundamental interaction between the constituent quarks within the neutron and to the fundamental interaction leading to its beta decay to become a proton.

We had a major role in the design, construction, and commissioning of a major instrument for nuclear and nucleon physics called BLAST. It used the 1 GeV electron beam at the Bates accelerator as a means to examine matter and fields on a scale ten thousand times smaller than the atom. The BLAST detector has now been disassembled and shipped to Germany, where it was used in the Olympus experiment at DESY.

More information about the group's activities is here

Professors: John Calarco, Maurik Holtrop, Karl Slifer, Patricia Solvignon

Nuclear and High Energy Theory

The research of the nuclear and high energy theory group ranges from the study of nuclear structure and Quantum Chromodynamics (QCD) to string theory. Prof. Heisenberg's nuclear structure simulation project explores how shapes, sizes, and interior density distributions of normal nuclei arise from the known forces between nucleons. Computer codes keep track of how strongly each combination of two particles interact with each other in all possible configurations. They also include the effects of how a third particle nearby can modify the force between those two particles. The stable configurations of nuclei assembled from sixteen particles can be calculated from all these interactions, two (or three) at a time. His program excels at determining and comparing the spatial relationships between the nucleons in the various low-lying nuclear energy levels.

Professor Beane is currently involved in theoretical research whose ultimate goal is to establish contact between nuclear and hadronic physics and Quantum Chromodynamics (QCD) --- the gauge field theory of quarks and gluons that underlies all of hadronic and nuclear phenomena. QCD is very hard to solve analytically; in fact very little is known about the exact solution. However, there has recently been remarkable progress in simulating QCD with computers using lattice gauge theory, which involves replacing space-time with a grid and using Montecarlo numerical-integration methods. The lattice QCD simulations are carried through using unphysically-large values of the quark masses. Furthermore, currently-utilized lattice spacings /lattice sizes are not much smaller/larger than characteristic physical length scales of interest, like the size of the proton. Fortunately one can formulate continuum effective quantum field theories which allow one to extrapolate from the unphysical quark masses, lattice spacings and lattice volumes to nature in a rigorous manner. The controlled theoretical error analysis provided by effective field theories is particularly crucial for searches for physics beyond the Standard Model of particle physics involving hadronic and nuclear experiments, and for the hadronic and nuclear input often required in astrophysics and cosmology. Professor Beane has been especially interested in making contact between the simplest nuclear systems, which involve two nucleons, and QCD using lattice methods. It turns out that the dependence of the two-nucleon systems (for instance the deuteron binding energy) on the quark masses that appear in the QCD lagrangian involves a low-energy parameter that cannot be determined from experiment. However, a lattice QCD simulation over a range of quark masses would enable a determination of the low-energy two-nucleon S-matrix as well as the parameter governing the quark-mass dependence. Knowledge of the quark mass dependence is not strictly academic as it would allow one to place bounds on the time-dependence of fundamental parameters --- like the Higg's vacuum expectation value--- using big-bang nucleosynthesis. These ideas have been bolstered by recent observations of distant quasars which suggest that the fine-structure constant was smaller in the distant past than it is today.

Professor Dawson calculates the properties of matter under the influence of QCD at very high temperature. These conditions probably existed a short time after the birth of the universe, and will soon be simulated with a new accelerator. These calculations will help us determine whether strongly interacting nuclear particles can undergo a phase transition at high temperature, radically changing their properties, much the way water boils and becomes steam. In the normal phase the quarks and gluons that comprise the internal structure of protons and neutrons are confined to stay inside. This new phase, called the quark-gluon plasma, would be a liberation of these internal constituents. The calculations will help us plan our measurements to determine whether the quark-gluon plasma occurs, and characterize its properties.

Professor Berglund studies string theory, the leading candidate for a theory of all the forces in nature. String theory employs one-dimensional objects, strings, as the fundamental building blocks and gives a unified description of the standard model of particle physics (quantum electrodynamics (QED), the weak interaction and QCD) and quantum gravity. In doing so, the theory predicts that the universe has more than four spacetime dimensions. These extra dimensions, however, play an important role in issues such as

  • the origin of matter
  • the different energy scales of the standard model of particle physics and quantum gravity
  • the small size and positive nature of the cosmological constant.

Research in string theory at UNH focuses on addressing these problems by studying the properties of the extra dimensions.

Professors: Jochen Heisenberg (emeritus) , Silas Beane, John Dawson (emeritus), Per Berglund

Medical Imaging

UNH physicists are engaged in fundamental research in producing nuclear polarization in gases and applying those techniques for medical imaging applications. Lung disease is the fourth leading cause of death in the US, yet there is no widely available modality to noninvasively image lung structure and function. Hyperpolarized gases, noble gases with their magnetic polarization enhanced by a factor of ten thousand, can be harmlessly breathed and imaged in the lungs. Imaging techniques can be devised to reveal gas space structure as well as functional information such as ventilation maps, local microstructure, and oxygen uptake.

UNH presently leads the world by more than a factor of ten in the quality and quantity of hyperpolarized xenon production. We are collaborating with imaging scientists at the Brigham and Women's Hospital in Boston to apply this technology to measuring lung surface-to-volume ratio in animals and humans. At our Center for Hyperpolarized Gas Studies we are implementing precision diagnostics to quantify the rate and degree of polarization, in particular by measuring the EPR shift of the rubidium fine structure due to polarized xenon, and we are investigating whether hyperpolarized xenon my be useful for providing early diagnosis of other diseases, such as cancer.

Professor: Bill Hersman

Physics Education Research

This is a the new but growing field of physics education research that probes the following kinds of questions: what are student difficulties in understanding physics concepts, in generating solutions to problems, in understanding what it means to learn physics; what kinds of activities can be developed to help students overcome theses difficulties; and how do we assess the effectiveness of the curriculum? There are also those who are very interested in cognitive theories of how we learn, and what are the basic pieces of our understanding on which all else is built. My past work included the development and assessment of an integrated calculus/physics course with an active-learning environment. Current work explores students understanding and use of mathematics within physics courses as well as an investigation into the assessment of physics problem solving skills.

Professor: Dawn Meredith