Research Projects
The projects and groups listed below are intended to provide interested
students with an overview of research offerings in the Department of Physics,
University of Washington. The list is not inclusive, but it is representative
of the breadth of research opportunities within the Physics Department and
INT. Students with particular interests should feel free to ask Wick or
Martin whether special projects can be designed: we have done this in past
years with good success.
NUCLEAR PHYSICS LABORATORY
Testing the Equivalence Principle using a High-Precision Torsion Balance
Faculty: Eric Adelberger, Jens Gundlach, Blayne Heckel
The Eot-Wash group is building a new instrument to make the world's most
precise test of Einstein's equivalence principle which says that gravitation
is equivalent to an acceleration of the coordinate frame and is the
underpinning of general relativity. You can find out more about this by
clicking on the Eot-Wash research group on the University of Washington
Physics Department home page on the Web. We have several interesting
technical projects suitable for experimentally inclined summer students.
Our lab is well equipped with instrumentation, machine and electronic shops
so that plenty of resources are available for attacking these problems.
Two examples are:
1) developing a higher performance optical system for reading out the twist
of the torsion balance
2) developing an actively controlled temperature-regulation system for
the torsion balance. We currently hold the temperature constant to a few
millidegrees and want to do better.
3) testing the noise performance of torsion fibers made of different materials.
Sub-millimeter-scale Tests of the Gravitational Inverse-square Law and Other Precision Tests of Gravitational Physics
Faculty: Eric Adelberger, Blayne Heckel, Jens Gundlach, and Ulrich Schmidt
The Eot-Wash group has begun a new project to test an exciting prediction that Newton's
inverse-square law could break down at the millimeter scale. If verified experimentally,
this prediction would provide strong evidence for more than 3+1 dimensions, i.e. that some of the
"extra dimensions" of modern theories could have detectable consequences. Our experiment employs
a novel torsion balance and a rotating attractor. Two REU students from last year's
program worked on the first version of this experiment which has just appeared in Physical
Review Letters.
We are also continuing to improve the torsion balance instruments used in our tests of Einstein's Equivalence Principle. These instruments, which currently yield the most precise tests of this important physical principle, are continuously being upgraded and provide many interesting projects for technically inclined students. Our lab is well equipped with instrumentation, machine and electronic shops so that plenty of resources are available for attacking these problems.
You can learn more about our group by clicking on the Eot-Wash research group on the University of Washington Physics Department home page.
The Sudbury Neutrino Observatory
Faculty: Peter Doe, Steve Elliott, Hamish Robertson, Tom Stieger, John Wilkerson
The Sudbury Neutrino Observatory (SNO) is a massive, heavy water Cerenkov detector in operation 2 km underground in Sudbury, Ontario. SNO's main research thrust is the study of solar neutrinos, but it is also sensitive to atmospheric neutrinos as well as neutrinos emitted from nearby (galactic) supernova. Using its unique neutrino flavor detection capabilities, SNO hopes to provide a definitive resolution of the long standing "solar neutrino problem", where all existing experiments observe fewer neutrinos from the sun than predicted by theory. Current explanations of the problem favor the existence of new neutrino properties such as neutrino mass and the violation of lepton family number. Work at UW in the summer of 2001 by our group (5 Faculty, 1 postdoctoral fellow, 8 graduate students) will concentrate on the operation of the detector system, analysis of the data being collected, and final preparation of a neutron detector system that will be used by SNO to make the key measurement of neutral-current neutrino interactions. There are numerous interesting research opportunities available. More information on SNO, plus other useful links can be found at our web site: http://EWIServer.npl.washington.edu/sno/sno.html
Weak Interactions, Symmetries, and Neutrinos
Faculty: Peter Doe, Steve Elliott, Hamish Robertson, Tom Steiger, and John Wilkerson
In addition to SNO, our group is involved in a number of projects probing the weak interaction and neutrino properties. Current projects underway include emiT, a precision neutron beta decay measurement that is testing time-reversal invariance, as well as SAGE, the Russian American Gallium Experiment. On SAGE we are involved in the analysis of data from this gallium based solar neutrino experiment (an experiment sensitive to the low-energy p-p fusion neutrinos). We are also investigating an idea for using Pb as a target in a new neutrino-oscillation search at an accelerator. The Pb nucleus has a relatively large cross section for neutrino interactions. An REU student is encouraged to consider working with us in any of these areas. More details of the research activities of the Electroweak Interactions Group are available at: http://EWIServer.npl.washington.edu .
The Washington Large Area Time Coincidence Array
Faculty: John Cramer, Steve Elliott, Jeff Wilkes
We propose to construct the Washington Large Area Time Coincidence Array (WALTA), an extended network of cosmic ray shower detectors, the elements of which will be placed in Washington area high schools. The primary functions of this network are physics education outreach and investigation of ultra high energy cosmic rays, the existence of which is one of the major unsolved problems of contemporary astrophysics. Work at UW in the summer of 2001 will include computer simulation of the response of the array to ultra high energy cosmic rays, prototyping an individual array element and characterizing its response to cosmic rays. An REU student would be a welcome participant in any of these activities.
Super-Kamiokande and K2K: Neutrino Oscillations Studies
Faculty: Jeff Wilkes and Steve Boyd
The Super-Kamiokande underground neutrino detector reported evidence for neutrino oscillations in 1998, and last year the K2K (KEK to Kamioka) long-baseline experiment began taking data with a high-purity muon neutrino beam, directed from a near detector site at KEK through the earth to Super-K. Students will have an opportunity to help on any of a wide variety of data analysis topics relating to these projects. Also, we will be preparing hardware for the planned Super-K upgrade in 2001.
Solar fusion of protons with beryllium-7 and the solar neutrino puzzle
Kurt Snover, Arnd Junghans, Eric Adelberger
The "solar neutrino puzzle," one of the current major puzzles in physics, consists of the observation that many fewer neutrinos from the sun are detected here on earth than are expected based on solar model calculations. We are in the process of making a new laboratory measurement of the reaction rate for the fusion of 7Be with low energy protons, producing 8B. In our Sun, high energy neutrinos originate from the decay of 8B produced by this reaction. This reaction rate is a crucial ingredient in the model calculations. An interested REU student is welcome to join us and participate in measurements, data analysis and interpretation of results.
Fundamental Physics with Ultra-Cold Neutrons
Faculty: Thomas Bowles
** This project is sited in New Mexico **
We are carrying out development work on an experiment to measure the beta asymmetry in the decay of polarized Ultra-Cold Neutrons (UCN). UCN are neutrons with velocities so low ( a few m/s) that they can be physically bottled and thus one can produce a compact source of neutrons to study neutron beta decay. We have constructed a prototype source at the Los Alamos Neutron Science Center (LANSCE) that is the most intense UCN source in the world. The UCN are produced from spallation neutrons made with the 800 MeV LANSCE accelerator that are moderated into the UCN regime using solid deuterium at 5 K. Research activities directed towards the beta asymmetry experiment involve design, construction, and testing of systems with the prototype UCN source, data acquisition and analysis, detector development, Monte Carlo simulations, and studies of systematic effects. We believe that a mix of some of these activities would provide a very good and broad learning experience for a REU student. The research would be carried out at Los Alamos National Laboratory, located in the mountains of northern New Mexico close to Santa Fe.
ASTROPHYSICS
Planetesimal Dynamics
Faculty: Tom Quinn, George Lake
From planet formation to planetary rings, from fragile comets and asteroids to sandpiles, there is a large diversity of problems related to planetary science that can be addressed with numerical simulations. For example, the surprising configurations of planetary systems recently discovered around nearby stars imply that planets can undergo large-scale radial motions during their formation. It is known that planetesimal scattering can cause a planet's orbit to shrink and circularize, but numerical simulations are needed to quantify this process for various disk parameters. As a different example, the spectacular breakup of Comet Shoemaker-Levy 9 and measurements of remarkably low bulk densities in some asteroids imply that small bodies in our Solar System may not be solid monoliths as we once thought. Numerical simulations reveal how these fragile bodies evolve but there are many parameters to explore. At even smaller scales, there are interesting topics in granular dynamics to investigate, such as self-organized criticality in sandpiles. The chosen project would provide experience performing simulations with sophisticated numerical code on a cluster of workstations and carrying out some analysis and visualization. We invite one REU student to join us in this effort. For more information, visit www-hpcc.astro.washington.edu/faculty/dcr or email trq@astro.washington.edu.
CONDENSED MATTER EXPERIMENT
Dynamics at Ice Surfaces
Faculty: Sam Fain
The environment of molecules of a given material near an interface is different from that of molecules in the bulk of the material, due to bonds missing at the interface. Thus the structure and dynamics near an interface can be quite different than in the bulk. Water ice is important in a number of environments on the earth, in the atmosphere, on comets and planetary satellites, and in space. Atomic resolution non-contact mode AFM measurements to investigate the structure, morphology, and annealing behavior of ice that is vapor deposited on various single crystal substrates in ultra-high vacuum work for temperatures between 50K and 150K using a new microscope manufactured by Omicron in Germany as well as a homemade low-current low-energy electron diffraction apparatus. The fundamental information obtained by such measurements will aid in understanding the influence of substrate on the growth and annealing behavior of ice at low temperatures such as occurs in the much colder environments in space where comets and dark interstellar media occur. An undergraduate student could assist in these experiments, learning about ice surfaces as well as about the surface physics techniques used. For more information see http://faculty.washington.edu/fain/research.html.
Physics of Thin Films
Faculty: Oscar E. Vilches
Our Low Temperature Physics laboratory is dedicated to the study of the phases of and phase transitions in very thin (one to a few atomic layers) films of simple gases on various surfaces. The goal is to understand the behavior of matter in quasi-two dimensions, particularly the importance of quantum effects on dimensionality. To make films of the various isotopic forms of He atoms and Hydrogen molecules, temperatures have to be reduced below 30K, while to study films of molecular nitrogen, methane, or Ar atoms temperatures can be in the liquid nitrogen temperature range. The laboratory is equipped with instrumentation to work below 1K (a dilution refrigerator), a cryostat to work above 1K using liquid helium, and small adaptable cryostats for work above 4K. Projects for Summer 2001 may involve joining graduate students studying mixtures of Helium 3 and Helium 4 below 1K adsorbed on graphite, hydrogen or deuterium molecules above 4K adsorbed on graphite or carbon nanotubes, hydrogen adsorption on gold, or Ar adsorption in silica particles. Three graduate and three undergraduate students are working currently on various projects related to the topics above. REU students have worked at the lab for four of the past five summers (1996, 98, 99, and 2000).
The Evolutionary History of the Three-Dimensional Microstructure of Bone
Faculty: Jerry Seidler
The advent of the third generation synchrotron radiation sources has provided experimentalists with x-rays of unprecedented intensity and collimation. One technique which has been especially enhanced by these new beam characteristics is microtomography, more commonly known as computerized axial tomography or CAT scans. Recent technological advances have pushed the spatial resolution of three-dimensional microtomography down to 100 nm. Our group is using microtomography to study the full three-dimensional microstructure of bone. We are particularly interested in bone development, including the evolutionary history of bone development. Our long-term goal is to arrive at a statistical mechanical model for bone remodeling, the processes by which bone is constantly reforming itself from the nano- to the macro-scale. A final successful model would have applications in paleontology, biology, anthropology, othopaedics, and forensics. The interested student would: (1) help with upgrading our tomography apparatus to make use of techniques from optical astronomy to mitigate defects on the CCD-based detector, (2) assist a local curator with preparation of bone samples from recent and paleontological specimens, (3) participate fully in data collection on a trip to the Advanced Photon Source x-ray synchrotron, and (4) be responsible for data processing and initial analysis. This work will not involve studies of live animals or animals which were destroyed for research purposes.
CONDENSED MATTER THEORY
Computer Simulations of Excited State Electronic Structure
Faculty: John J. Rehr, A.L. Ankudinov
While density functional calculations of ground state electronic structure are now well developed, as recognized by the 1999 Nobel Prize, calculations of excited state properties and response functions are much less developed. Our group is especially interested in ab initio calculations of high energy excitation spectra, as measured by synchrotron x-ray sources. Improved numerical algorithms, e.g., for parallel computers and faster matrix inversion are needed to speed up the calculations.
ATOMIC PHYSICS
Atomic Tests of Parity Nonconservation and Time Reversal Symmetry
Faculty: Norval Fortson, Blayne Heckel, Michael Romalis
Students will be able to work directly on small scale atomic physics experiments that probe the elementary particle physics frontier. In one type of experiment, the electroweak force between electrons and quarks inside atoms is measured by the small degree of left-right asymmetry displayed by these atoms. In another type, a permanent electric dipole of an atom is being looked for as evidence of forces that distinguish between forward and backward in time. Other experiments include laser trapping of Yb atoms and applications of atomic magnetometers to biological measurements. In these experiments students can use and develop high precision lasers, ion traps, laser cooling techniques, and other tools of modern atomic physics.
Precision Measurements on Single Trapped, Laser-Cooled ions
Faculty: Hans Dehmelt, Justin Torgerson, Warren Nagourney
We work entirely with single atomic ions at rest in space. The ions
are stored for long periods (up to a month) in an electrodynamic ion
trap and are brought to rest using the radiation pressure of a laser
beam. By studying essentially motionless ions in such pristine
isolation, extremely precise measurements can be made. One application
being vigorously pursued is the construction of a single-ion optical
frequency standard. An atomic clock based upon such a standard could
have an accuracy of one part in 1018 (or about one second in the
lifetime of the universe). REU students can help with the myriad
mechanical, optical and electronic tasks needed to bring these
experiments to fruition. Since certain single ions can be seen with
the slightly aided human eye (aided by a simple microscope), the
interested student can experience an intimate connection with atomic
matter not available in most other disciplines.
PHYSICS EDUCATION GROUP
Research-based Instructional Strategies for Teaching Physics
Faculty: Lillian C. McDermott, Paula Heron, Peter Shaffer, Stamatis Vokos
The Physics Education Group conducts research on student understanding of physics and uses the results to guide the design of instructional materials, which are intended for national distribution. The effectiveness of these curricula is assessed at the University of Washington and at many other institutions. REU students will have the opportunity to participate in programs shaped by the group's research, such as the summer program for K-12 teachers and the tutorials for the introductory physics course. In addition to taking part in classroom activities, previous REU participants assisted in investigations of the effect of different instructional strategies on student understanding of important fundamental concepts by analyzing student performance on qualitative questions before and after instruction.
EXPERIMENTAL PARTICLE PHYSICS
Muon tube Quality Control and Monitoring
Faculty: Henry Lubatti
We are responsible for constructing a large number of proportional drift tubes that will form a precision muon detector for the LHC ATLAS experiment. The wires in the tubes must be very precisely positioned, and their tensions be within strict limits. The student would be involved in managing the system that performs these quality checks, taking the actual measurements, and managing the associated data base.
D0 Muon Chamber Commissioning
Faculty: Henry Lubatti
For students willing to spend some time at Fermilab, we have lead responsibility for the installation and commissioning of the D0 muon detectors. Under the supervision of physicists, students would help mount the chambers, connect and verify gas flow, apply high voltage and signal processing cables, and perform cosmic-ray tests. The teachers would be expected to learn about muon properties, such as lifetime.
D0 Level 3 trigger
Faculty: Gordon Watts
UW is heavily involved in D0, a collider detector located at Fermilab, near Chicago. UW has a primary responsibility for the command and control software for the D0 Level 3 trigger system. To participate, a student should have some computer programming experience. We are currently finishing up the control system and supporting it running online in Chicago. One new area of work is web presentation of monitor information. We are also heavily involved in physics analysis, currently working on top quark and Higgs boson searches. Finally, we are also looking forward several years to building a new version of D0. To do this correctly a number of physics studies and detector simulations must be performed. Projects are available in all of these areas.
GLAST Simulation
Faculty: Toby Burnett
UW has a lead in the design and operation of the simulation for the GLAST satellite-based gamma ray detector, scheduled for launch in 2005. We will be designing a system to perform simulations on demand, allocating computing and data storage resources to the task. The physics involves properties of the flux of cosmic-ray particles impinging on the Earth from space, and interactions of gamma rays in matter. The latter can be studied with the simulation tool itself.
THEORY
Effective Field Theory in Nuclear Physics
Silas Beane and Effective Field Theory Group
Effective field theories (EFTs) are based on the simple idea that details
of the short-distance interactions of a system of particles should not
strongly affect the low-energy properties of that system. They offer ways
to systematically include information on the interactions between the
particles at short range while making only minimal assumptions about this
dynamics. Hence, EFTs have proven extremely useful in exploring the ways
in which effects not included in the "standard model" of particle physics
might manifest themselves in low-energy observables.
In recent years much effort has been invested in applying these ideas in
nuclear physics. We know that the forces between neutrons and protons are
very complicated at short distances, and yet we believe that these
complications should be irrelevant for many nuclear physics phenomena. The
University of Washington has been a leader in this work. Some of us have
focused on applying effective field theory to a number of aspects of the
physics of the neutron-proton system. Others have been involved with the
issues which arise when one attempts to apply the ideas of effective field
theory to a systems of three and four neutrons and protons. This REU
project is an exciting opportunity for an undergraduate student to become
involved in work which represents an innovative approach to nuclear
physics. It would provide training in nuclear theory, quantum mechanics
and field theory which would be good preparation for graduate school
courses on these topics.
Light Front Quantum Mechanics
Faculty: Jerry Miller
In 1947 Dirac introduced a new form of relativistic quantum mechanics
in which the variable ct +z acts as a "time" coordinate and ct-z acts
as a "space" coordinate. This so-called light front formalism was
largely forgotten until the 1970's, when it turned out to be useful in
analyzing a variety of high energy experiments. Despite the
phenomenological success of this formalism, it has enjoyed only
limited use in computing wave functions of particles and atomic
nuclei. The present project is devoted to using the light front
formalism to solve quantum mechanics problems involving bound and
scattering states. A mathematically strong REU student would learn
about relativistic quantum mechanics through the process of solving
the relevant relativistic equations. This project would involve
working on interesting and timely topics and could provide great
preparation for graduate school quantum mechanics, field theory or
even string theory.
RESEARCH IN PHYSICS OF MUSIC
Faculty: Vladi Chaloupka
Physics of Music investigates the production, propagation and perception of musical sound. Current projects include room acoustics studies using modern "minimally intrusive" techniques, physics of consonance/dissonance (including a project using real-time MIDI control to achieve context-dependent tuning), experiments on absolute pitch perception, and measurement and evaluation of pipe organ sound, with emphasis on the role of physical imperfections necessary to achieve the perception of perfection. The lab is equipped with advanced hardware and software, including the CLIO system based on the Maximum Length Sequence method (used in many 'spread-spectrum' applications). Recently, we added LabVIEW data acquisiton hardware and software. In addition to Physics, these projects touch on Computer Science, Electrical and Mechanical Engineering, Hearing Research, and of course Music. Many aspects of this research are well suited for the participation of undergraduate students.
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