2000 Physics REU
University of Illinois at Urbana-Champaign

PROJECT LIST


1. ATLAS Scintillating Tile Hadron Calorimeter Professor Steve Errede
ATLAS link

Project Description: Dr Errede's High Energy group is working on detectors for the ATLAS experiment, designed for CERN's Large Hadron Collider. They are building Scintillating Tile Hadron Calorimeter Submodules and testing photomultipliers which will read signals from the TileCal. Over the next three years, the group will build ~200 submodules and test ~3000 phototubes. They are, and will continue to be, very busy!

Qualifications: Computer languages, lab experience (UIUC's 301 for example), upper level physics courses.


2. Manipulating Biopolymers 'in silico' Professor Klaus Schulten
Theoretical Biophysics Group
Paper published by previous REU student

Project Description: The Theoretical Biophysics Group at the Beckman Institute operates a very advanced computational laboratory in the area of molecular biophysics and biomolecular modeling. The group is developing software that permits the graphical representation and manipulation of biomolecules, e.g., the stretching of muscle proteins or the extraction of ligands from enzymes. The software combines the group's graphics program VMD and molecular dynamics modelling program NAMD. The hardware is a PC with advanced 3D graphics together with a so-called haptic device that contains a mechanical pointer which communicates into the program 6D information (position and orientation) and receives feedback from the computer in the form of a 3D force felt by the user. The project would involve learning to operate the device which will still be in the stage of development and to apply it to investigate a particular protein system.

Qualifications: Only a student with extraordinary computer skills (knowledge of C and C++, Windows NT, basic Unix), interested in graphics and high performance computing (skills can be learned, but high motivation necessary) as well as in application of physics to biomedicine could be considered since the hardware/software is still in development. Students need to have a good basis in classical mechanics. A detailed description of your computer experience is required when applying for this project.


3. Physics Education Research Professor Gary Gladding

Project Description: Participants will have the opportunity to study the effectiveness of revisions made to the UIUC introductory physics sequence. The participant will be responsible for studying the relevant literature, analyzing data and creating questions to test conceptual understanding. Participants will also take part in an ongoing study to test retention of physics concepts.

Qualifications: Participants must have a good understanding of the concepts and problems in the introductory physics sequence. An interest in physics education is essential. General computing experience (programming, spreadsheets, HTML, ....) will be helpful.


4. Electronic and Magnetic Devices Made with Highly Correlated Materials Professor Jim Eckstein

Current Research: We have been studying the physics of colossal magnetoresistance using manganite films grown by atomic layer-by-layer molecular beam epitaxy. The films are atomically flat and have low temperature transport rivaling that of single crystal samples. In our best samples, we have observed low temperature residual resistivity of less than 50 m W -cm. We have studied simple patterned transport samples extensively. We have observed a large anisotropy in magnetic behavior and magneto-transport that we attribute to spin orbit scattering. We have also seen that the metal insulator transition in our samples is independent of the magnetic state of the sample. That is, when the sample magnetization is fixed, the metal insulator transition occurs at a fixed temperature, independent of magnetization.
     More recently, we have begun to study tunneling into these materials by assembling single crystal tunneling structures. These consist of a base manganite film, covered epitaxially with a titanate barrier layer. Since the two species are well lattice matched it is possible to grow such an interface continuously. The barrier is followed by an in-situ deposited gold film. The trilayers are patterned into mesa structure. Interpretation of the tunneling is complicated by the spreading resistance of the manganite, which can be large. When the manganite is the most conducting, however, its is possible to obtain tunneling spectra that are predominantly due to the tunnel junction. These spectra show metallic behavior in the manganite and no significant sign of the gap structure recently reported in samples investigated by ex-situ scanning tunneling spectroscopy. A small reduction in conductivity is observed near V=0, but this appears to be unrelated to the data shown in the STS report. We propose that the metallic tunneling obtained in these structures grown with epitaxial and in-situ interfaces is due to a metallic and ungapped density of states at the Fermi energy in the manganites.

Qualifications: None specified


5. Electronic Musical Instruments Professor Steve Errede

Project Description: This summer, Dr Errede will be working on experiments for a course entitled "The Physics of Electronic Musical Instruments." Some of the areas he is studying are:

Work on the project would include electronics, programming, computer-based data acquisition, and web development, depending on the selected student's abilities and interests.

Qualifications: Experience with electronics, C programming, web page construction, and/or computer based data acquisition.


6. Nonlinear Dynamics and Chaos in Nanoscale Materials Professor David Campbell
Papers involving previous REU students

Project Description:
     This project combines fields of "deterministic chaos/nonlinear dynamics" and the condensed matter physics of "nanoscale materials." The result is a study of the fundamental physical properties of novel materials with potential applications to future electronic devices. Let's start with a brief background on the two separate subjects involved in this research.
      In recent years, the subject of "chaos" has captured the public's imagination to an extent almost unprecedented for a technical, mathematical concept. As the celebrated scene from "Jurassic Park" suggested, to the popular mind chaos is a sort of cosmic Murphy's Law: if something can go wrong, it will. In fact, an encyclopedia definition of chaos might read (in fact does read, since I wrote it !):

CHAOS: the complicated nonperiodic evolution in time of deterministic nonlinear dynamical systems that on the long-term is unpredictable and equivalent to a random process because of exponential sensitivity to the initial conditions.

      In common parlance, this means that some sufficiently nonlinear systems, although completely deterministic (that is, with no "hidden" random forces), can {\it behave} (on sufficiently long times) as if they were as random as a fair coin toss.
      Despite its arcane origin and technical description, chaos is a very common real world phenomenon, observed in many experimental systems. One goal in this project is to discover if, when, and how chaos can manifest itself in the motion of electrons---ie, the current---through particular kinds of novel solid state systems---``nanoscale materials''---that may eventually lead to a range of new electronic devices.
      To understand how this might be, we need to provide some background on the second ingredient in the project: "nanoscale materials." Modern molecular epitaxy techniques---ie, "physically engineering" materials by growing them one layer of atoms at a time---have made possible the fabrication of ``superlattices'' consisting of layers of different semiconducting materials, such as GaAs and GaxAl1-xAs. These "vertical semiconductor superlattices" (VSSLs) can readily be fabricated with 100 alternating layers, with the layers being between 2 and 20 nanometers thick: hence the name, "nanoscale matertials." From our understanding of the theory of solids -- which is based on the idea of electrons moving in the periodic potential of the ions making up the lattice of the solid -- we can show that these alternating layers appear to be "artificial" one-dimensional solids in the direction perpendicular to the layers, since their equal spacing creates a periodic sequence of potential wells. Instead of being determined by the natural bond lengths of the atoms in an ordinary solid, the spacing of the potential wells in the superlattices is an easily varied parameter and can be chosen to amplify a number of nonlinear physical effects that are masked or unobservable in normal solids. Importantly, since many of these effects are associated with the response to applied electric fields, they can have potential applications in technological devices.
      In addition to these VSSLs, one can create "gated lateral semiconductor heterojunctions," (GLSH) in which an effectively two-dimensional "gas" of electrons is subjected to external potential----eg, periodic in space, or a double barrier---caused by metallic "gates" on the surface of the semiconductor. Further, for both VSSLs and GLSHs, the effects of external fields cause still more interesting nonlinear phenomena.
      Previous REU participants Matt Cargo and Jon McKinney contributed substantially to our understanding of this problem and were involved in publications related to their work. If you are interested in seeing further details or our approach and results, you should look at these references.

K. N. Alekseev, G. P. Berman, D. K. Campbell, E.H. Cannon, and M. C. Cargo, "Dissipative Chaos in Semiconductor Superlattices," Phys. Rev. B (1996).

K. N. Alekseev, E. H. Cannon, J. C. McKinney, F. V. Kusmartsev, and D. K. Campbell, "Spontaneous dc Current Generation in a Resistively Shunted Semiconductor Superlattice Driven by a TeraHertz field," Phys. Rev. Lett. 80 2669-2672 (1998).

K. N. Alekseev, E. H. Cannon, J. C. McKinney, F. V. Kusmartsev, and D. K. Campbell, "Symmetry-Breaking and Chaos in Electron Transport in Semiconductor Superlattices," Physica D 113, 129-133 (1998).

Qualifications: Experience with Mathematica, Fortran or C++ prefered but not essential. Courses in Quantum Mechanics and Advanced Classical Mechanics preferred but not essential.


7. Quark Sub-structure of the Proton Professor Douglas Beck

Project Description: Professor Beck's group is leading an experiment to study the quark sub-structure of the proton. In this project they are responsible for the construction of a large superconducting magnet which we expect to be delivered this summer. The group's responsibilities include precise characterization of the magnetic field using a computer controlled measurement device. They would like the assistance of an undergraduate in the development of the testing program for the magnet.

Qualifications: Familiarity with programming (c/c++), general lab hardware experience.


8. Real Compton Scattering Professor Alan Nathan

Project Description: Professor Nathan is currently studying real Compton scattering (RCS) at the Thomas Jefferson National Accelerator Facility. His group is studying the underlying structure of the proton by observing how the fundamental constituents (quarks and gluons) interact with each other. To measure the probability of Compton scattering, a beam of high-energy protons, a proton-containing target, and a pair of detectors to detect the recoil proton and the scattered photon are needed. This summer Professor Nathan's group will need help assembling and tesing a 216 element detector for Jefferson Lab.

Qualifications: Some lab experience would be helpful.