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Graduate Program» Research Opportunities for Graduate Students


Research Opportunities for Graduate Students





Accelerator Physics and Technology at the SNS

The Spallation Neutron Source (SNS), at Oak Ridge National Laboratory, is the most powerful accelerator-based neutron scattering facility in the world. Because of SNS' unprecedented high beam intensity and other novel features (such as the world's first superconducting proton linac) there are several challenging accelerator physics research areas at SNS. In addition, the enhancement of the SNS accelerator complex to attain full power and beyond offers tremendous research opportunities in:

  • Computational, theoretical and experimental studies of the dynamics of high-intensity charged particle beams, with emphasis on multi-particle and collective effects
  • Experimental investigations of charged particle beam measurement and control
  • Development of laser-based diagnostics and manipulation techniques for charged particle beams
  • Development of high-current H- ion source technology

Past graduate student theses:
S. Cousineau, Indiana University, Advisor Jeff Holmes: "Understanding Space Charge and Controlling Beam Loss in High Intensity Synchrotrons" M. Doleans, University de Paris, Advisor Sang-ho Kim: "Studies of Elliptical Superconducting Cavities at Reduced Beta" Y. Sato, Indiana University, Advisor Jeff Holmes: “Electron-Cloud Effects and the Electron-Proton Instability in the SNS Accumulator Ring” J. Wilson, University of Tennessee (Electrical Engineering), Advisor Yoon Kang, “Investigation of Propagation Characteristics of Twisted Hollow Waveguides for Particle Accelerator Applications”

Present graduate student research projects:
D. Bartkoski, University of Tennessee, Advisors Jeff Holmes and Craig Deibele: “Nondestructive Beam Profile Measurement
Z. Liu, Indiana University, Advisor Jeff Holmes: “Loss Modeling of the SNS Accumulator Ring”

There are at present two openings for graduate student research in Accelerator Physics at the SNS. More information can be found at the following sites:
General project information: http://neutrons.ornl.gov/
Accelerator physics group: http://neutrons.ornl.gov/APGroup/

Contacts: Stuart Henderson, iyu@ornl.gov or telephone (865) 241-6794
Jeffrey Holmes, jzh@ornl.gov or telephone (865) 576-5570
Martin Stockli, qma@ornl.gov or telephone (865) 241-8817

Chemical Physics Research and Atmospheric Physics

Our group investigates nature at the boundaries between physics and chemistry which is now called Chemical Physics. Both physics and chemistry graduate students pursue research on a wide variety of topics. Undergraduate students are also an important component in this research and greatly assist the graduate students in their research. The Compton group is well funded with an NSF Grant in Chirality research, a new NSF Grant for the study of Negative Ions, a STAIR/IGERT Grant in Hydrogen Storage and an EPA Grant to study nanomaterials in the environment. One underlying theme of the research involves the study of singly- and multiply-charged negative ions. Included in this research is the characterization of dipole- and quadrupole-bound anions. These are very diffuse and weakly bound anions which play a role in the transport of electrons through gases and along surfaces. Our group is also interested in the detection and characterization of anions in the atmosphere as well as their potential role in the complex physics and chemistry of the atmosphere. Students in the Compton Group may also be involved in ongoing research at Aarhus, Denmark and at the Free Electron Laser (FELIX) in the Netherlands.

The Compton group is well equipped with a large array of experimental apparatuses as well as the full compliment of equipment in the Department of Chemistry (Raman, NMR, CD, UV/VIS, X-Ray, Mass Spectrometrs, etc.). High resolution electron beams and pulsed tunable lasers are employed to study the spectroscopic properties of gaseous molecules in nozzle-jet expansions or nano-materials produced by laser-matter interactions. A technique employing Raman Spectroscopy of samples under liquid nitrogen is used to examine the symmetric (Raman allowed) vibrational energy levels and a Bomem DA8 FTIR spectrometer is employed to record the asymmetric (IR active) vibrational modes.

Every graduate student is assisted in her/his research with computational methods (e.g., Gaussian) and expertise needed to interpret experimental data. Chemical Physics research prepares the student for a wide variety of job and post doctoral opportunities. The last seven group members are now: in charge of the Undergraduate Physics laboratories for the Jr. Colleges in South Carolina, permanent employee at ORNL, employed as a research scientist at Abbot Laboratories, Professor at the University of Mississippi, Faculty member at the University of Calgary, Post Doc at Univ. of Scherbrooke, in charge of AMOP at the FELIX Free Electron Laser in Holland.

Presently, there are openings for two full RA and one split TA/RA appointments.

Further information is available online at: http://web.utk.edu/~rcompton/link.html.

Contact: Dr. Robert N. Compton at rcompton@utk.edu

Condensed Matter Theory: Correlated Electrons, Nanotransport, and Computational Methods

One of the most active areas of research in physics is Condensed Matter. A variety of investigations in recent years have unveiled interesting complex phenomena in several materials, that challenge our understanding of solids and may also lead to technological applications. Prominent among these developments are the areas of (1) High Temperature Superconductors, with critical temperatures that have reached over 150 K and with exotic pairing properties, (2) Colossal Magnetoresistance Manganites, with changes in DC current of many orders of magnitude upon the application of small magnetic fields, and (3) Nanosystems, where quantum effects play a key role. Some members of the Condensed Matter Theory group carry out investigations in these fields and several related ones. The main tools to analyze models for these materials involve computational techniques, since typically there are no small parameters to guide a perturbative expansion, but analytical calculations are also performed. The broad area of investigations outlined in this paragraph is usually referred to as Strongly Correlated Electrons. This field of investigations is also much related with the popular area called Complexity, due to recently unveiled similarities between soft and hard materials.

The UT/Physics Department group working in this research context has a high international visibility, and publishes in prestigious journals such as Physical Review Letters, Science, Physics World, and others. For a list of recent publications see http://sces.phys.utk.edu. The group consists of two professors (Distinguished Professor E. Dagotto and Professor A. Moreo), and several students and postdocs. We receive the frequent visits of collaborators from the US and abroad.

A variety of clusters of PCs are available for the application of computational methods to the study of the materials described above. This includes clusters located at both UT and ORNL, and the combined number of PCs as of April 2005 was close to 300.

The group has a strong relation with the Theory Group of the Condensed Matter Sciences Division (CMSD) of Oak Ridge National Laboratory.

Multidisciplinary Research in Nanoscale Science and Devices

Dr. Thomas Thundat's research programs at the University of Tennessee and the Oak Ridge National Laboratory focus on mechanical and electronic manifestations of molecular and photonic interactions at interfaces and interphases. Understanding the physics and chemistry involved in the nanomechanical and nano-optical effects of interaction at interafces is important in designing and developing miniature sensors and devices that exploit the nanoscale effects. For example at micro and nanoscale, delicate forces such as photonic, surface tension, thermocapillarity, Marangoni, Knudsen, electrostatic and van der Waals interactions play a significant role because of the large surface to volume ratio in nanoscale systems. Similarly, interaction of photons with electrons in a metal nanostructure, have a range of important applications such as all-optical modulation and switching, surface enhanced Raman spectroscopy (SERS), tip field enhancement a.s.o. However, our understanding of mechanics and function at the nanoscale is far from complete. Recent progress in development of instrumentation that can measure displacements and forces into the nanoscale and sub nanoscale regimes is paving the way for a very exciting convergence of many traditionally separate fields and disciplines ranging from molecular biology to fluid mechanics to quantum mechanics, and to device physics and engineering. Present applied research programs include:

  • Scanning probe microscopy (SPM) for nanoscale imaging
  • Atomic Force Microscopy (AFM)
  • Subsurface Force Microscopy (SFM)
  • Near Field Scanning Optical Microscopy (NSOM)
  • Photon Scanning Tunneling Microscopy (PSTM)
  • MEMS and NEMS sensors for the detection of chemical, biological, and explosive material; basic studies of nanoscale interactions
  • Standoff detection using quantum cascade lasers
  • Standoff IR spectroscopy of trace anlaytes
  • Photoacoustic spectroscopy
  • Plasmonics, experimental and computational work on surface plasmons
  • Nanoscale Visible and IR Spectroscopy of nanomaterials

We can support one or two new graduate students full time.

Contacts:
Dr. Thomas Thundat at thundattg@ornl.gov or tthundat@utk.edu
Dr. Ali Passian at passian@utk.edu

Neutron as Probe to Study Strongly Correlated Electron Materials

We focus on the scientific challenges and opportunities associated with understanding the highly correlated electronic behavior exhibited in transition metal oxides (TMOs). TMOs have been at the forefront of condensed matter physics research since the discovery of high-transition-temperature (high-Tc) superconductivity nearly 15 years ago, and interest in these materials continues unabated because of the richness of their novel properties. The outstanding characteristic of these materials is the dominant role played by electron-electron, electron-lattice, and spin-lattice interactions. Most recently, the discovery of iron arsenic based high Tc superconductors again highlights in the importance of TMOs. Reaching a satisfactory understanding of these "highly correlated electron systems" poses one of the most profound intellectual challenges in the physical sciences today. Our objective of this research program is to explore and understand the microscopic origins of various phases in the TMOs using neutron scattering as a primary tool. The program has two key components: advanced synthesis and neutron scattering. For synthesis, we will use infra-red floating zone furnace located at 317 and 320 SERF to grow the most interesting single crystals including copper oxide and iron arsenide superconductors. Neutron scattering is an indispensable tool for studying the highly correlated electron materials, and for this we will use the newly upgraded high-flux isotope reactor (HFIR) at the Oak Ridge National Laboratory (ORNL) as well as other world-class facilities in US and Europe. The materials are iron arsenide superconductors, high-Tc copper-oxide superconductors and other interesting strongly correlated materials. The prospect for future job opportunities for graduate students is excellent. Of the three Ph. D graduate students graduated from PI’s group, two are already junior faculties in research Universities in the US. The third student currently works at NIST center for neutron research as an instrument scientist. We will have one opening for full RA support in the Fall of 2010, perspective students are encouraged to meet with Dr. Pengcheng Dai in 407A Nielsen.

Further information is available online at: http://pdai.phys.utk.edu/

Contact: Dr. Pengcheng Dai at piq@ornl.gov

Nuclear and Particle Physics at the Spallation Neutron Source

Our goal is to address such questions as the origin of Time Reversal Non-invariance, spontaneous symmetry breaking, and the Big Bang by studying the particle properties of the neutron. Using the Spallation Neutron Source at ORNL as well as other intense neutron sources such NIST’s research reactor and the Institut Laue Langevin’s (Grenoble, France) high flux reactor, we address such experimental questions as the neutron electric dipole moment, the free neutron lifetime, and the details of parity violation in nuclear processes. The work involves a wide variety of techniques including charged and neutral particle detection, ultra-low temperature cryogenic system, polarized beams, etc. This work should appeal to experimentalists who enjoy hands on physics as well as broad theoretical ideas.

Further information is available online at: http://www.phy.ornl.gov/nuclear/neutrons/

Contact: Geoff Greene via e-mail at ggreene@utk.edu.

Nuclear Theory: Structure of Rare Isotopes and the Quantum Many-Body Problem

The research of the low-energy nuclear theory group at UT concerns the study of nuclei and nuclear astrophysics, which addresses the origin of the elements, the structure and limits of nuclei, and the evolution of the cosmos. The main questions for this field are: What binds protons and neutrons into stable nuclei and rare isotopes? What is the origin of simple patterns in complex nuclei? When and how did the elements from iron to uranium originate? What causes stars to explode? The new and exciting frontier in nuclear theory lies in the description of rare and short-lived nuclei. These nuclei have unusual ratios of neutrons to protons. In this unique situation, important inter-nucleon interactions are isolated and amplified. The weak binding of neutron-to-proton asymmetric systems add additional flavor to the nuclear many-body problem. Exciting new properties are, e.g. neutron halos, proton radioactivity, and changes in shell structure.

The UT/ORNL nuclear theory group consists of Drs. D. J. Dean, G. Hagen, W. Nazarewicz, T. Papenbrock, several long- and short-term visitors, postdoctoral associates, and students. We investigate many aspects of the nuclear many-body problem with particular emphasis on rare isotopes. We employ microscopic methods (involving density functional theory, coupled cluster theory, Monte Carlo simulation, and shell model diagonalizations), and tackle theoretical challenges with pencil and paper, PCs, and the world’s most powerful supercomputers. We also apply our ideas to other many-body problems, e.g., to ultracold atom gases. For more details, please see the titles of our recent publications, and come to our seminar. The group has several international visitors each year, and collaborates with experimental nuclear physicists at UT and ORNL. A few potential projects are described below.

Theoretical Description of Nuclear Fission

Nuclear fission is one of the best examples of nuclear large-amplitude collective motion. It is also a complicated many-body process which is difficult to treat on the microscopic level. Various nuclear structure models have been applied to fission barriers, lifetimes, and mass/charge distributions, and they provided good overall description of the phenomenon and, in many cases, detailed predictions. On the other hand, it is also true that the microscopic description of fission, based on effective nucleon-nucleon interactions, still does not exist. The aim of this project is to attack the problem of spontaneous fission using modern theoretical methods and computational tools. This project is supported by the grant from the National Nuclear Security Administration.

Contact: Dr. Witold Nazarewicz at witek@utk.edu.

First-principles nuclear structure calculations with the coupled-cluster method

We are using the coupled-cluster methods for first-principles calculations of selected nuclei that are of current experimental and theoretical interest. Within this approach, a similarity-transformed Hamiltonian is constructed that decouples from few-particle—few-hole excitations. The application of this method involves diagrammatic derivations, and a numerical implementation of the derived expressions. Students working in this area would actively participate in code development and calculations for relevant benchmark nuclei. The scientific questions we address relate to the role of three-nucleon forces in nuclei, and the evolution of shell structure in exotic nuclei.

Contact: Dr. Thomas Papenbrock at tpapenbr@utk.edu.

Particle Physics: Study of Neutrino Properties

When in 1930 Wolfgang Pauli invented neutrino particles for the explanation of beta-decay experiments he bet a case of champagne that nobody ever would be able to detect these particles. Nowdays detection of neutrinos is a field of precision experimentation in Physics: we recently learned in our KamLAND experiment that neutrinos have masses and can transform from one type to another. The next set of  questions to study in neutrino experiments are the hierarchy of neutrino masses and whether CP-symmetry is violated in neutrino interactions. Such a violation might be a mechanism of cosmological leptogenesis and an explanation of matter-antimatter asymmetry in the Universe.

The key to such measurements is the determination of an important mixing angle theta_13 between the neutrino mass eigenstates.Theta_13 will be measured in the "Double Chooz" experiment that is being constructed at a nuclear power plant in France and where UT is participating in the construction of the first of two neutrino detectors. We invite interested graduate students to participate in the construction of the second Double Chooz detector in France next year and also in the following neutrino measurements and data analysis in the international team of researchers. We anticipate a PhD project to be ready in 2012.

We also invite graduate students to participate in another neutrino project, NOvA, where a 2 GeV neutrino beam will be directed from the NuMI source at FermiLab to the huge, 15kt, detector to be constructed in Minnesota at a distance of 810 km from the neutrino production target at FermiLab. This experiment will be able to compare neutrinos with antineutrinos produced by the particle beams, will determine the neutrino mass hierarchy and observe possible CP-violation effects. We expect the student to be involved in the initial tests of the detector prototype in neutrino beam at FermiLab starting next year, but also in simulations, and data analysis. Expected PhD project completion is 2012-2013.

We know that neutrino has very small but nonzero mass. Howeverits value never been measured. "Majorana" double beta decay experiment could have enough sensitivity to measure it. We are looking for a graduate student who like to get his/her hands on experience working with ultra pure materials in the state of the art sensitivity range. Work will include extensive communication with other members of the large Majorana collaboration between dozen of Universities and three US National Laboratories.

Further information is available online at the following sites:

Contacts: For "Double Chooz" and "NOvA," contact Dr. Yuri Kamyshkov, office 505 in the Nielsen Physics Building, telephone 865-974-6777 or e-mail kamyshkov@utk.edu. For "KamLAND" and "Majorana," contact Dr. Yuri Efremenko, office 503 in Nielsen Physics Building, telephone 865-974-7857 or e-mail yefremen@utk.edu

Quantum Devices, Nanoelectronics, and Nanophotonics

Collective electronic quantum effects on the nanoscale are under investigation for the development of semsors and signal electronics, all-photonic amplification, thin-film displays, current modulation in conductors via photonics, photovoltaics, and other applications. Sensors are based upon novel systems that are micro-electro-mechanical systems (MEMS) or nanoscale systems. The associated electronics has an application-specific integrated circuit (ASIC) developed jointly with industry and providing radio transmission and signal processing in a self-contained system. Quantum tunneling in metal-oxide-metal junctions is being explored and junctions are fabricated using electron-beam lithography. Sensors now under development for the National Institutes of Health include implantable sensors for the detection of changes of biochemical compounds and physiological signals. All-photonic amplification and methods for induction of electronic current modulation in conductors are studied with surface plasmons, which are quanta of collective electronic effects at surfaces. Optical fiber sensors using nanoparticles of gold as a coating are researched for detection of a variety of environmental compounds. The group has also developed new forms of scanning-probe microscopy and spectroscopy using photon tunneling and the tunneling of surface plasmons. Other projects include a micro-optical spectrometer based upon surface plasmon filtering and the development of a molecular-beam technology for coating of sensors.

See movies of Dr. Ferrell's research: taking the pulse train in the infrared and transferring it to visible light (Movie One, Movie Two).

Contact: Dr. Thomas L. Ferrell at tferrell@utk.edu.

Relativistic Heavy Ion Physics

The research of the Relativistic Heavy Ion Physics (RHIP) group is focused on the study of nuclear matter at extreme temperatures and densities, which is a new and exciting field on the borderline between nuclear and high energy physics. At these extreme conditions of temperature and density nuclear matter will undergo a phase transition to a Quark-Gluon Plasma. In this new phase nuclear matter no longer consists primarily of protons and neutrons, but instead consists of deconfined quarks and gluons in a state that mostly resembles a superfluid liquid. Experimentally, we are creating high temperature nuclear matter by colliding heavy nuclei (heavy ions) at very high energies (ultrarelativistic energies) at nuclear accelerators.

Specifically, we are working within two large collaborations: the PHENIX Collaboration at the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory, Long Island, New York, and the ALICE Collaboration at the Large Hadron Collider (LHC) at CERN, Geneva, Switzerland. We also collaborate closely with researchers in the High Energy Reactions Group in the Physics Division at ORNL.

In general, the RHIP group has two to four students involved in our research at different stages in their graduate studies, a post-doc, and two professors, Ken Read and Soren Sorensen. We are always looking for new students, so please do not hesitate to check us out at: http://www.phys.utk.edu/rhip/ or contact us directly through the contact info at: http://www.phys.utk.edu/rhip/RHIP_People.htm. We are in particular looking for students with an interest in working within large collaborations at the cutting edge of science and technology and with an interest and willingness to travel extensively to the large accelerator centers in New York and Switzerland.

Theoretical Biological Physics: Spatial Stochastic Dynamics in Biological Networks

I am looking for a few graduate students and one postdoctoral scholar to work on application of statistical physics, stochastic processes, and nonlinear dynamics to the dynamical behavior and the collective phenomena in complex biological systems. In particular, we are interested in the effect of network topology and intrinsic/extrinsic noise on the dynamics of key components in the biological networks of our interest. We also have a keen interest in application of non-equilibrium statistical physics to the spreading phenomena of infectious diseases. The prospective graduate students are expected to be familiar with graduate level (preferably non-equilibrium) statistical physics, to demonstrate an interest in learning stochastic processes and nonlinear dynamics, and to work closely with both experimental and theoretical biology colloborators. However, the most important qualification for those positions are a demonstrated burning desire to jump into the wonderful world of the interface between physics and biology.

Please email Jaewook Joo at jjoo1@utk.edu if you are to discuss the above open positions.

Theoretical High Energy Physics: Strings and Quantum Gravity

The High Energy Theory group is currently working in the rapidly developing subject of black holes and other extended objects in string theory. Despite its shortcomings, string theory is still the only viable quantum theory of gravity. Recent results on black holes, D-branes, etc. are very exciting, having considerably advanced our understanding of quantum aspects of gravity such as thermodynamicalproperties of black holes (e.g., entropy), Hawking radiation and the information loss paradox. Their cosmological implications are also being investigated.

For more information, visit our Web site, or contact Dr. George Siopsis (e-mail: siopsis@tennessee.edu)

Web Site: http://aesop.phys.utk.edu