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Physics- Astronomy Department 
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the National Superconducting Cyclotron Laboratory Giant Magnetoresistance (GMR) in thin, artificial multilayers, composed of alternating layers only a few atoms thick of ferromagnetic (F) and non-magnetic (N) metals, is of interest both scientifically and technologically. Scientifically, we want to understand the physical sources of the GMR, both in the bulk F and N metals and at their interfaces. Technologically, GMR is of interest for devices as diverse as tape reading heads, position and motion sensors, and magnetic random access memory (MRAM). Our group at MSU pioneered measurements of GMR with current perpendicular to the layer planes, where the physics is more transparent than in standard measurements with current in the layer planes. An REU student in this program would learn a variety of experimental techniques, including fabricating multilayers in a state-of-the-art sputtering system, measuring very small resistances at cryogenic temperatures using Superconducting Quantum Interference Devices (SQUIDs),measuring magnetizations with modern SQUID magnetometers, determining multilayer structures with x-rays, etc. A specific project would be chosen after discussion with the student, to take account of the student's particular interests.
In billiards, the dynamics of the collision is determined by the the impact parameter of the collision. This is also the case in nuclear collisions. However, it is impossible to directly observe the course of a nuclear collision, and the centrality of the collision has to be inferred indirectly from experimental observables. We will develop a new experimental measurement for the centrality, test it on a simple model, and also apply or centrality filter to experimental data obtained from heavy ion collisions. Some computer programming experience is required for the modeling. No prior knowledge of nuclear physics is needed.
If heated and compressed enough, atomic nuclei can undergo a phase transition not unlike the boiling of water. We will study experimental observables of this transition and compare them to a very simple model of nuclear fragmentation. Some computer programming experience is required for the modeling. No prior knowledge of nuclear physics is needed. However, an introductory-level knowledge of thermodynamics or statistical mechanics would be helpful.
The class of materials known as transition metal oxides continue to turn up surprises. Most recent was the discovery of a very large response of the electrical resistivity of manganate compounds to the presence of a magnetic field: "colossal magnetoresistance". This has technological implications because these materials could be used as magnetic field sensors, for example, in the hard-drive of computers and other magnetic storage devices. However, their properties are also a mystery on a fundamental scientific level, and we are attempting to understand this. This project involves using novel x-ray data measurement and analysis techniques to elucidate the local atomic structure of these materials as they change from a metal to an insulator with varying temperature and composition. This gives us information about how the electrons in the material, which give it its interesting properties, are coupled to the atomic lattice, and how this coupling is important to the properties of the material. Preliminary work in this area is described on my my web-page.
My group studies the physical properties of "mesoscopic" samples, i.e. samples with dimensions less than a micron or so. Samples of this size often behave very differently from larger samples, especially at low temperature. They allow us to observe physical phenomena that are washed out on longer length scales or at higher temperature. This summer my group plans to convert our data acquisition system from one based on programming languages to one based on LabVIEW. LabVIEW is a commercial graphical programming environment that enables one to develop new applications more quickly than by writing in a traditional programming language. An REU student could develop some simple LabVIEW applications, and use them to measure electrical properties of mesoscopic samples at low temperatures.
This project involves a collaboration between physicists and chemists to synthesize new compounds with novel magnetic (and perhaps superconducting) behavior and understand the nature of the physical processes involved in that behavior. The student who works on this problem will do both experimental and theoretical work in the physics department. Starting with new compounds synthesized by students in the chemistry department at MSU she/he will measure the magnetic properties and use a rather simple, but powerful, mean field technique to relate the measured properties to a theoretical model. A similar REU project in 1997 resulted in two scientific papers for the student.
It is likely that the next generation of electronic devices will use dots and wires which are 0.1 micron in linear dimension. The electronic response of these small structures is dominated by quantum effects. In this project, the growth of dots and wires in this size regime will be modelled, using both computer simulations and simple analytic tools. Factors controlling the quantum dot architecture are the deposition flux, the substrate morphology, diffusion rates and the substrate and dot material structures. An REU student will develop simple models for predicting conditions under which quantum dot self-assembly is favorable.
Nature often finds highly optimal structures (e.g. proteins). In analysing problems in solid state physics and in biology, it is difficult to develop algorithms which efficiently find optimal structures. An REU student will learn some new approaches to optimisation of structures in solid state physics (e.g. spin configurations in magnets, flux line configurations in magnets). This requires knowing or being will to learn programming in either C or Fortran.
Recently at Stanford free electron laser facility femtosecond laser pusles were used to investigate experimentally the dynamics of defects in crystals. We propose to analyze this dynamics theoretically. We will investigate self-induced change of light polarization. Polarization effects are one of the most simple for experimental investigation, yet one often just would not expect such effects to occur in a cubic crystal. The system of particular interest can be thought of as a hydrogen atom inserted into a cubic crystal, and we will investigate resonant excitation of the 1s -> 2p optical transition. There are many systems which can be described by this model, including donors in most commonly used semiconductors and localized vibrational excitations of impurities. We have already done some preliminary work, we are quite excited about the results, and we hope to be able to finish the work in the summer. The skills required from a person who will join the group include the ability to solve systems of linear differential equations on the computer. The relation to quantum mechanics and optics will be learned on the way.
With the aid of two large Neutron
Walls, we are investigating important questions of nuclear physics and of nuclear
astrophysics, as summarized in the two paragraphs below.
The Neutron Walls greatly enhance the study of neutron-rich nuclei such as helium-8 (2
protons and 6 neutrons) and lithium-11 (3 protons and 8 neutrons). These nuclei are almost
pure neutron matter, and much remains to be learned about them. Because the valence
neutrons are lightly bound and form a diffuse halo, the slightest interaction detaches
them; the neutrons then carry out information on the halo structure to their detectors,
the Neutron Walls.
As stars burn hydrogen into helium and then build heavier elements, neutron accretion
plays a role in the buildup process.
When the accreting nucleus is radioactive, a laboratory measurement of the accretion
probability is impossible. However, we have been able to perform the inverse
measurement, one in which the heavier element is caused to emit a neutron, which is
observed with the Neutron Walls. Then, from the principle of time reversal
invariance, the probability of neutron accretion is computed.
The Walls have been used in a number of experiments, and much data analysis is in
progress. However, a job that will affect most of the experiments remains to be
done--we have to know the absolute efficiency of the Walls for detecting neutrons.
This is the project for the REU student. It can be completed by the student this
summer. There will be guidance and assistance from me and other members of my group,
but it is pretty much a one-person job. The project has an experimental part and a
computational part. The experimental part is to use some radioactive sources to
determine the attenuation length of light in a cell of the Neutron Wall. The
computational part is to write a computer code that simulates the process of light
production (by neutron-proton collisions) and transmission to the two ends of the
cell. The results will be submitted for publication in Nuclear Instruments and
Methods.
We invite a student to participate in the implementation of a recently funded array of position sensitive Germanium photon detectors. This summer we will concentrate on assembling and testing nuclear electronics and interfacing to the real-time data acquisition system. Familiarity with computers is required for the data analysis, and command of a high-level programming language is a plus.
The high energy physics group at MSU is involved in experiments at the current energy frontier (CDF and D0 at the Fermilab accelerator near Chicago) and at the energy frontier of the future (the ATLAS experiment at the CERN accelerator near Geneva, Switzerland). Detector work is currently going on for both CDF and ATLAS. Activities this summer will include design, construction and testing of high energy physics detectors as well as development of high energy physics related physics demonstrations. There will be opportunities for analysis of physics data from CDF as well as test beam data from ATLAS. Several trips to Fermilab are likely.
There are numerous aspects of using computers in the teaching/learning environment. Their use has the potential for enhancing both effectivness and efficiency, as they may be able to provide to a very large group of students the type of instruction and learning interactions usually reserved for small classes. In the study of physics, it has become increasingly evident that the conceptual aspects of the field are the major hurdle for most students. They often reach for a formula, then plug and chug, hoping that the answer is correct. The correlation between the understanding of concepts and overall performance is extremely strong. The design of questions and exercises dealing with concepts is a highly beneficial process for instructors, as part of the process is to identify misconceptions and designing methods that will induce students to shed these misconceptions. In this REU project, the student will participate in all aspects of preparation of such exerciszes, from the identification of the misconception to the final coded work ready for use in a class. The tool used is CAPA, a networked tool developed to implement a Computer-Assisted Personalized Approach for assigments, quizzes and examinations. The particular topics involved in the project will be determined after discussion with the REU participant. A second aspect of the project is the analysis of the feedback received by students to help improve the effectiveness of the system.
We are designing a camera for the Wyoming Infrared Telescope that has a very large field of view (twice that of the full moon). With a parabolic telescope, as this one is, the images near the telescope axis are sharp, but off-axis images suffer from coma: The images look like comets and not points. The goal of the REU project is to design a ``Wynne corrector,'' a triplet or quartet of lenses that removes the coma.
In a photometric survey with 8 colors of selected regions of the sky, we discovered some very faint stars near the subdwarf turn-off. (That means these stars are metal poor, being subdwarfs, and have nearly exhausted hydrogen in the cores.) These stars are 10-20 kpc from the sun and therefore serve as a probe of the outer halo of the Galaxy. The question for the REU project is whether it is possible to determine differences in elemental composition between these distant halo stars and nearby halo stars, whether the distant halo formed from material that is more pristine than the nearby halo.
It is well known that certain systems known as amphiphiles, containing both a hydrophilic as well as a hydrophobic part in one unit, can arrange themselves in a variety of shapes when dissolved in water. For example, surfactants which consist of hydrophobic tails made of hydrocarbon chain and hydrophilic head groups exhibit self-assemblying properties. Even at very low concentrations surfactants form objects called micelles in such a way that the hydrophobic tails go inside to form the core (since they want to avoid water) with the heads protruded at the water boundary and shielding the tails. With increasing concentrations surfactants can also form long cylindrical micelles which in turn can arrange themselves in a periodic hexagonal array. Other well known forms in which surfactant self-assemble are known as bilayers which can turn into a vesicle when the flat surface of the bilayer bends and the two ends merge. The physics of soft-condensed matter systems forming membranes, micelles, and vesicles is already a very interesting subject by itself since some of the issues go beyond the study of inanimates to biology. Analytic theories and numerical work have been able to answer many of the questions. Recently the field has been further enriched by experiments where it has been realized that these organic surfactants of various shapes can be used as templates or structure directing elements to design and fabricate inorganic nanoporous materials which typically span 10-100 A. Controlled synthesis by adjusting the surfactant properties, e.g. chain length, concentration etc. of these so called nano and meso phases of matter is of great practical importance. A theoretical study of these surfactant-host composite systems is naturally very demanding and exciting. Recently we have developed simple continuum models of surfactant-host systems with which we can study some of the phenomena described above. Surfactants are extended objects and hence can move from one point to another by (i) reptation (with which the surfactant will bodily move like a snake) and (ii) kink-kump (with which it wiggles its back-bone or the tail). By these movements surfactants can come close to each other and minimize the energy of certain combinations of staying together. These calulations will greatly simplify, if instead of continuum, we restrict the surfactants to move only on a lattice. There are compelling reasons to believe that certain general features of self-assembly will not depend on these lattice models of surfactants. The advantage of studying lattice models is that not only they are simpler but computationally more efficient. The codes are already written and simple to understand. Some experience with simple computer codes is desirable. The project will introduce the student a new and exciting area of future research. A similar REU project two years ago was published in a reputed journal by the student and us.
The development of radioactive ion beams at facilities like the NSCL has allowed access to new regions of the chart of the nuclides for the elucidation of the decay properties of exotic nuclear species. In an experiment carried out at the NSCL in December 1997, a Ge-76 beam at 70 Mev/A was fragmented in a Be target to produce a series of neutron-rich nuclides having Z > 28, N > 40. An REU student will participant in the analysis and interpretation of results from this experiment. This will include the use of the NSCL data analysis programs to examine beta-gamma and gamma-gamma coincidence data from the ground state decays of Co-67 and Cu-71. The particle-triaxial rotor model (PTRM) will also be applied to understand better the systematic trends in the low-energy structure of these nuclides.
RR Lyrae stars are pulsating giant stars, which typically pulsate with only a single period. Some RR Lyrae stars pulsate in more than one mode simultaneously. Double mode RR Lyrae stars pulsate simultaneously in the fundamental mode (typically 0.5 day) and the first overtone mode (typically 0.3 day). Blazhko effect RR Lyrae stars have a secondary periodicity of some tens of days, much longer than the fundamental mode. The theoretical understanding of multimode RR Lyrae stars is poor. In this project, CCD observations of RR Lyrae stars will be analyzed to shed light on the multimode phenomena.
About fifteen years ago, physicists at IBM invented the scanning tunneling microscope (STM), ushering in a new era for the study of surfaces. By monitoring the quantum mechanical tunneling between the surface of a solid and a sharp tip, the STM can produce amazing pictures. You can actually see the individual atoms that make up the material. In addition, the microscope can be used as a local probe of the electronic properties-- with atomic resolution. We use STM and similar techniques to probe the physics of electronic interactions in conducting materials. During the summer, we will be building and testing two systems. REU students would be welcomed to work on various aspects of these projects, depending on the student's interest and experience.
Proteins are large macromolecules that affect just about every property that characterizes a living organism. The functionality ascribed to proteins is diverse, ranging from storing and/or transporting particles, mediating signaling processes to providing a means for converting between chemical and mechanical energy. Proteins are built up from a linear sequence of 20 basic building blocks, called amino acids. A particular sequence of amino acids will fold up into a well characterized three dimensional structure that will generally consist of rigid substructures and floppy regions. The floppy regions make it possible for the protein to undergo low energy conformational changes that take place over long times (milliseconds or greater), and these motions play an important role in biological functionality. We have recently developed a combinatorial algorithm, based on constraint counting theorems from graph theory, that identifies the Floppy Inclusion and Rigid Substructure Topography (FIRST) of a given protein structure. The summer project for the interested REU student is to apply the FIRST algorithm to trajectories 9from a molecular dynamics simulation) defining the protein structure over a series of time frames. The objectives of the project are to quantify the level of precision given by the FIRST algorithm, and to characterize the mechanical stability through the FIRST analysis. This project is most suitable for a student interested in biophysics and/or computational biochemistry. Programming in FORTRAN will be required.
The theoretical elementary particle physics group is engaged in a comprehensive project to perform "global QCD analysis" which applies the theory of Quantum Chromodynamics (QCD) and the Quark Parton Model to describe a wide range of high energy elementary particle processes. The REU student will be introduced to the current understanding of the elementary particle physics world and the structure of strongly interacting particles (such as the proton) in terms of quarks and gluons. He/she will work with the supervising faculty and a research associate to apply tools of the global analyses to new experimental results from the high energy accelerators, and to work on the parton distribution functions of the proton. These parton distribution functions describe how quarks and gluons are distributed inside the proton.
Solid state Nuclear Magnetic Resonance (NMR) is a novel approach to macromolecular structure determination and involves measurement of specific interatomic distances and angles with radiofrequency pulse sequences and magnetic fields. We are currently using solid state NMR to investigate the structures and dynamics of both AIDS-related proteins and magnetic materials. The AIDS proteins bind to human receptors and antibodies and structural data for them should greatly aid in the development of HIV vaccines and therapeutics. In addition to our disease and materials-specific research, we also develop new solid state NMR techniques for biological and other macromolecules. Our work includes NMR physics, analytical quantum mechanical calculation and computer simulation, building apparatus, and RF electronics. For more information, please e-mail me at weliky@cem.msu.edu.
The response function of a detector is the relationship between the characteristics of the particles which enter the detector and the signals it produces in 'response' to the particles. This spring the 4p Group at the NSCL installed a new, 60-element array of silicon & cesium iodide detectors for use in nuclear reactions studies. This exciting addition to the 4p Array distinguishes not only the charge and energy of fragments emitted from nuclear collisions but also the isotopes of these fragments, greatly broadening our research capabilities. Before data from our recent experiment can be analyzed, the response function of the new array must be determined. This is carried out by combining data from the experiment and a special calibration run. The project will require developing a keen understanding of:
The response function will then be incorporated into our existing analysis programs, allowing it to be utilized in future 4p experiments. For more information, go to the 4p Group home page.
The ion cyclotron resonance accelerator is a novel concept for accelerating ions that has not yet been experimentally demonstrated. We are currently building a low energy demonstration model and will be working on the ion source and beam injection system over the summer. In this system the ion source will operate while immersed in a magnetic field and beam will be extracted along a magnetic field line. Therefore, alignment and position adjustments are critical. An Einzel lens will focus the beam, then electrostatic bending plates will bend the beam onto the proper orbit for injection into the high magnetic field region of a superconducting solenoid. The REU student who works on this project will assist in the design and building of components for the ion source and beam optics. The work will involve computer modeling of the beam trajectory, making parts in the machine shop, and taking beam measurements. This project is recommended for a student who wants hands-on experience with accelerator components. The student should have completed at least one semester course in electricity and magnetism and be generally computer literate. Machining experience would be a plus, but is not necessary as it will be gained on the job.
Nuclei with a number of particles in an upper partly filled valence shell frequently have large shape fluctuations around average spherical equilibrium. This happens when vibrations around the sphere have a low frequency and large ampltude. In this situation "normal" approaches to the description of nuclear states fail. Currently a huge amount of experimental information is accumulated which is not well understood. Using simple physical ideas we can try to find some trends which may serve as guidelines for a future microscopic theory. The purpose at this stage is to construct phenomenological models capable of describing the main features of observed data. Some knowledge of basic quantum mechanics is necessary.
26. LOCALIZATION OF SOUND IN THE BRAIN, Prof. W. Hartmann
To localize sounds, the brain uses a comparison of the signals in the two ears. In a free
field, these two signals are coherent and their cross-correlation function correctly
points to the source of the sound. In a room, reflections from the room surfaces may
produce interaural incoherence, which we suspect leads to uncertainty about the source
location. Alternatively, reflections may produce interaural coherence, albeit with a
cross-correlation function that misleads the listener.
This summer's REU project is a study of interaural coherence and cross-correlation
function as measured in a reverberation room with an artificial head. A goal of the study
is to investigate particular geometries
that are expected to produce different degrees of coherence with cross-correlations of
varying reliability. A second goal is to compare the physical measurements with human
perception.
27. ELECTRONICS FOR ACOUSTICS DEMONSTRATIONS, Prof.
W. Hartmann
Analog and digital electronics is being constructed and programmed for an interactive
perceptual demonstration hall called the Waves Place. This summer's REU project consists
of constructing signal generating electronics for acoustical demonstrations, where the
signal characteristics are heard, seen, and controlled by the observer. Some (but not
necessarily much) experience with electronics would be helpful.
The National Superconducting Cyclotron Laboratory at MSU has the unique capability of
producing beams of short-lived nuclei. Our group studies the decay of nuclei along the
proton dripline, which means that these nuclei decay by emitting protons. One
specially interesting decay mode is the emission of two simultaneous protons. Although
predicted over 30 years ago it has never been observed experimentally. Last summer we
found first evidence for this decay mode in the first excited state of 17Ne. We
plan to improve the experimental setup in order to confirm our first tentative results.
This summer we intend to test a magnet together with a silicon detector array as a
possibility to separate, detect and measure the protons in coincidence with the heavy
fragments (15O). The REU student will be involved in these tests and will
work directly with the large magnet and the silicon array including the vacuum system, the
electronics and the data acquisition.
Many nuclear physicists are presently directing their efforts towards the determination
of the thermodynamic properties of nuclear matter. One of these properties, namely the
phase transition between bound nuclear matter
and a gas of free streaming nucleons, can be experimentally studied at the NSCL by
colliding two heavy nuclei. We will be performing two experimental measurements of
nucleus-nucleus collisions this summer. One experiment will be aimed at determining the
temperatures and densities achieved for collisions in which there is some evidence that
such a phase transition may be occurring. These experiments provide an ideal opportunity
for a summer student to gain experience with the experimental techniques utilized in
strong interaction studies. For a very highly motivated REU student, the project could
lead to inclusion on subsequent publications.
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Physics- Astronomy Department
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the National Superconducting Cyclotron Laboratory