PHYSICS DEPARTMENT

Nationwide the percentage of students majoring in Physics is about 0.3%. At Williams the physics majors are 4% of the class, i.e. about 10 times the national average. The average number of majors per class at Ph.D. granting institutions is 11 while at Williams the current numbers are 22 seniors and 20 juniors. While these numbers are not large in absolute terms (there is still plenty of opportunity for student/faculty interaction in and out of the classroom), it does mean that Williams is a nationally significant producer of future physicists. About half of our majors choose to go on to graduate programs in physics, applied physics, astrophysics, engineering, computer science, mathematics or other scientific fields (along with the odd composer or economist thrown in for good measure). Currently we have five alumni studying towards a physics Ph.D. at Harvard.

We are proud that one of our 2002 graduates, S. Charles Doret, was selected as the winner of the 2002 LeRoy Apker Award. This national award is given by the major professional society of physicists, the American Physical Society “To recognize outstanding achievements in physics by undergraduate students, and thereby provide encouragement to young physicists who have demonstrated great potential for future scientific accomplishment.” Two awards are given annually and competition is quite intense. The award was based largely on Charlie’s thesis work, Precise Measurement of the Stark Shift in the Thallium 6P1/2  7S1/2 378 nm Transition, with Prof. Tiku Majumder. Charlie received the award at a ceremony at the March 2003 meeting of the APS in Austin, TX. In addition to an honorarium for Charlie, the Physics department received an award of $5000 to support undergraduate research. Charlie is currently working towards a Ph.D. in physics at Harvard University.

On April 11-12, Williams hosted a joint meeting of the New England Sections of the American Physical Society and the American Association of Physics Teachers. We had a fine turnout of some 131 participants including 34 graduate and undergraduate students (plus many of our local students who sat in on some portion of the meeting). Friday’s invited talks were on “Quantum Bits.”

The Williams Inn provided a pleasant dinner after which Prof. Richard Wilson of Harvard University gave a thought provoking talk on “The Role of Physicists in Public Policy.” On Saturday, we had two invited sessions, one on Ultrafast Pulses Beyond the Visible Spectrum, the other on Teaching of Physics. A list of the invited talks can be found at the end of the Physics section.

The meeting also included contributed talks, posters (included several by our own physics and chemistry students) and a series of workshops for teachers.

The college has identified a number of curricular areas where it wants to expand offerings. Of particular interest to the Physics department are interdisciplinary courses and tutorials. These are both areas where the department has already made a major investment of faculty time and effort and we are hopeful that the college will be able to provide the resources to support these efforts in the long run.

In the area of interdisciplinary courses, we are currently offering 300 level courses on Protecting Information: Applications of Abstract Algebra and Quantum Physics (with the Math Department) and Materials Science: The Chemistry and Physics of Materials (with the Chemistry Department). In 2003-04, Prof. Aalberts will be offering a new course on Computational Biology (with the Computer Science Department). In addition we are offering a course open to both science and non-science majors on Science and Religious Experience.

The Physics Department has been an early and enthusiastic supporter of tutorials. We have evolved a variation on the canonical tutorial format, which works well for physics. The weekly cycle starts Thursday evening when students read a chapter in the text (sometimes along with an article from the literature). Friday, there is a one hour lecture/discussion session for the whole class. Students then spend a few days working on problem sets. Tuesday or Wednesday, each pair of students meets with the professor for an hour presenting their solutions thus far and discussing any questions that have arisen. Thursday, students turn in written solutions and the whole cycle begins again. While this is a demanding schedule for students and faculty, we find that the extra effort is well rewarded by the improvement in student’s problem solving skills. We have converted our standard upper level courses on Electromagnetic Theory, Classical Mechanics and Applications of Quantum Mechanics into tutorials. Most of our graduate school bound students take at least two such tutorials.

We are very pleased to report that in support of our efforts to teach tutorials and interdisciplinary courses, the college has added a new tenure track faculty position to the department. Dr. David Tucker-Smith will be joining us next year. A graduate of Amherst College, his Ph.D. is from Berkeley and he is currently a post-doc at MIT. His research is in elementary particle physics beyond the standard model. Next spring he will be teaching an upper level course, Gravity, which will introduce students to the General Theory of Relativity. This course will help strengthen the astrophysics route through the major.

As we noted last year, the college has received an extraordinarily generous bequest for the support of teaching and research in the Physics Department. Mrs. Frances McElfresh Perry has left the college some 12 million dollars in honor of her father, Prof. William Edward McElfresh, who taught at Williams 1902-1936. Prof. McElfresh was chair of the Physics Department from 1905 until his retirement. At this point, the college is still deciding how to use the very generous gift, but we are hopeful that a small portion will be used to support summer students (in addition to those already supported by the existing Somers and Synnott funds). This summer, the Bronfman Science Center was able to be unusually generous in supporting summer students, and we expect to have 18 students doing research with Physics faculty. We hope that in future years the McElfresh gift can be used to support this high level of student participation.

Assistant Professor Daniel Aalberts was awarded a $155,183 grant by the National Institutes of Health for his proposal, “Splicing, Folding, and Stretching Nucleic Acids.” This year, he and Nathan Hodas ’04 modeled how intramolecular base stacking interactions effect the physical properties of stretched DNA, investigated novel RNA pseudoknot structures, and studied the statistical thermodynamics of DNA “gene chip” microarrays. Aalberts and Jeff Garland ’03 developed the “finding with binding” method to identify RNA splice sites, an approach that equals the best statistics-based techniques. His work with John Parman ’02 and Noel Goddard (Rockefeller University) exploring intramolecular interactions in DNA was published in Biophysical Journal. This summer, Eric Daub ’04 will join the Aalberts group to model alternative splicing in RNA.

Aalberts taught Particles and Waves---Enriched (PHYS 141), Mathematical Methods for Scientists (PHYS/MATH 210, and Statistical Physics (PHYS 302). Aalberts is one of the founding members of the College’s new Bioinformatics, Genomics, and Proteomics (BiGP) program. In fall 2003, he offers a new course, Computational Biology (PHYS/CSCI 315).

Aalberts advised the Society of Physics Students and served on the Committee for Educational Policy. He sang with student/alumni/faculty quintet “With and Without” and faculty quartet “the Diminished Faculty,” performing in Thompson Chapel and in classrooms. Aalberts was promoted to Associate Professor, with tenure, on 1 July 2003.

Associate Professor Sarah Bolton enjoyed her 2002-03 sabbatical leave. She spent the year in Williamstown, working in her lab with honors student Sarah Nichols ’03. The two Sarahs continued the Bolton lab’s studies of semiconductors using an ultrafast Titanium Sapphire laser. The laser produces pulses of less than 20 femtoseconds in duration (20 x 10-15 seconds) - short enough to take “snapshots” of electron motions and molecular vibrations. We are using the laser to determine how these very fast motions are altered when the electrons in a material are confined to two dimensions. This year the work progressed significantly, as our new NSF grant allowed us to take measurements with samples held at Liquid Helium temperature (4K). Working at such low temperatures allows us to control all of the energy in the sample using the optical pulse. This project will continue in the summer of 2003 with Jenni Simmons ’05, Zophia Edwards ’05, and thesis student Jesse Dill ’04.

This year Professor Bolton again reviewed grants for the National Science Foundation, in both the Engineering and Condensed Matter Physics programs. She was also a reviewer for the journals Optics Communications, Optics Letters, and Physical Review.

Emeritus Professor Stuart Crampton continued to teach his interdisciplinary course, Science and the Religious Experience. He has received a $4000 grant from the American Scientific Affiliation to bring distinguished speakers to campus next year to interact with this course and to give public lectures on the general topic of the relationship of science to religion. He continues as a consultant for the Sherman Fairchild Scientific Equipment Program, and he has recently been elected Chairman of the Board of Directors of Research Corporation, America’s oldest science-related foundation.

Professor, and department chair, Kevin Jones continues to collaborate with the Laser Cooling and Trapping group at the National Institute of Standards and Technology in Gaithersburg, MD headed by Dr. William Phillips. In collaboration with NIST scientist Dr. Paul Lett, Jones uses the cold atom facilities at NIST to study collisions between atoms at <1/1000 degree above absolute zero. Atoms colliding in the presence of laser light can “photoassociate” to form molecules. From detailed study of these photoassociation spectra one can learn about the nature of the atomic collisions. The detailed understanding of the collision properties they have derived from these photoassociation experiments is proving to be essential background information for understanding other experiments on Bose-Einstein condensates and for proposed experiments on quantum computation.

In the summer of 2002, Jones received a grant from NIST to support Rachel Gealy ’04 as part of their Summer Undergraduate Research Fellowship program. Working with Jones and Lett, as well as other visiting scientists at NIST, she did experimental and theoretical work on a novel non-linear optics effect. She was able to explain the somewhat curious behavior of diffraction patterns formed when two laser beams cross in a liquid crystal material. A paper based on her work is in the review process.

Jones (aided in summer 2001 by Sarah Iams ’04) and several other NIST scientists have completed a series of measurements on the very highest vibrational levels of the triplet ground state of the sodium dimer. Although Na2 is one of the best studied of all molecules, the new measurements are orders of magnitude more accurate than earlier measurements where they existed and fill in an important gap in our knowledge of the highest levels. This work has been accepted for publication in the Journal of Chemical Physics.

Aubryn Murray ’05 will accompany Jones to NIST in summer 2003, supported by a grant from NIST, to continue experiments on ultracold molecules. Jones and his colleagues have been able to produce and detect ultracold ground state molecules. This work was reported in a 2002 paper in The Physical Review. Thus far, the molecules have not been trapped and simply fall to the bottom of the vacuum chamber under the force of gravity. Using a large magnetic field gradient, it should be possible to trap the molecules and, if all goes well, study collisions between molecules and atoms at temperatures well below those accessible by other techniques.

On the teaching side, Jones has been teaching our upper level tutorials on electromagnetism and classical mechanics and is endeavoring to develop polished course materials that can be passed along to future instructors. He has also been revising some of the lab exercises in our sophomore level Waves and Optics course.

Jones was an outside reviewer for the Swarthmore College honors program and for a number of research journals and granting agencies, including Physical Review Letters, The Journal of the Optical Society of America, The Physical Review and The American Journal of Physics.

During the summer of 2002, Associate Professor Protik (Tiku) Majumder supervised four students in the summer research program. Charlie Doret ’02, having graduated in June 2002, spent his third summer in the lab. Charlie worked on writing up a manuscript describing his thesis work measuring the “Stark shift” in thallium using UV laser light, a thallium atomic beam, and a high-voltage electric field. This paper was submitted in the summer and appeared in print in Nov. 2002 in the journal Physical Review A. As Charlie’s thesis result built upon development work of his two predecessors in the lab, this paper had additional co-authors Paul Friedberg ’01, and Andrew Speck ’00. Charlie also helped to introduce incoming thesis student Christopher Holmes ’03 to the experiment and the apparatus. In July, Charlie and Prof. Majumder presented two posters on work in the lab at the 18th International Conference on Atomic Physics (MIT, Cambridge, MA). First-year students Josh Cooperman and Joe Kerckhoff also joined the research group and completed a number of projects associated with a new experimental effort to use thallium atoms to search for time-reversal-violating forces.

Prof. Majumder had a busy fall, teaching both PHYS 131 and PHYS 109, the latter being the course he developed some years ago with Prof. Sarah Bolton in which students learn about sound and light and wave phenomena in a small, interactive, hands-on format. In the spring, Prof. Majumder taught the Quantum Mechanics tutorial, PHYS 402T to a large and hard-working group of 15 students. He also served this year as a member of the College’s Committee on Priority and Resources.

The Majumder group continues to pursue high-precision diode laser spectroscopy of thallium in their atomic physics lab. A better understanding of the structure of this complex atom is essential to be able to interpret recent precise measurements of parity nonconservation (i.e. the “Weak” force) in thallium in terms of fundamental physics. With aid from the new NSF grant supporting this research, a new postdoctoral research associate, Dr. Michael Green, was hired and arrived at Williams in November from Adelaide, Australia. The department is happy to welcome Michael to Williams! He has quickly come up to speed on the experiments in the Majumder lab and worked closely with thesis student Chris Holmes during the academic year. Chris’ thesis work involved the development of a new method of spectroscopy and signal processing designed to improve the detectability of a weak transition in thallium. Chris worked on optical, electronic, and data acquisition/analysis projects, and upgraded aspects of the thallium atomic beam oven system. He demonstrated the potential of this new experimental method, “two-tone FM spectroscopy”, by using a thallium vapor cell, and this summer the technique will be extended to the atomic beam. Chris Holmes and Michael Green attended the annual APS “DAMOP” conference in Boulder, CO (May 2003) and presented a poster on the FM-spectroscopy work that comprises Chris’ thesis.

Chris Holmes ’03 will be continuing work in the lab for part of summer 2003, prior to beginning an M. Phil. degree in Philosophy of Physics at Cambridge University, UK, this fall. We look forward to having incoming thesis student, Mark Burkhardt ’04, as well as sophomores John BackusMayes ’05 and Colin Bruzewicz ’05, join the research group in June to work with Dr. Green and Prof. Majumder in pursuing the thallium spectroscopy experiments this summer.

Associate Professor Jefferson Strait taught Electricity and Magnetism (PHYS 201), in the fall term and Electromagnetism and the Physics of Matter (PHYS 132), in the spring term. He also taught a course called Light, Color, and Vision for the Berkshire Institute for Lifetime Learning (BILL). A lively group of about 30 senior citizens attended the six lectures and viewed several of the optics demonstrations from our department’s collection.

As an outreach project with the local public high school, Strait arranged for the Advanced Placement Physics students from Mount Greylock Regional High School to come to Williams on seven occasions to do experiments in our new David Park Teaching Laboratory. These visits enabled the students to use equipment that is unavailable at most high schools. Several of the students commented that this opportunity significantly enhanced their appreciation of physics. Mr. Kevin Forkey, the Physics Department Lab Supervisor, deserves our thanks for setting up the equipment and for taking care of many of the details of these visits.

Strait and his students have built an optical fiber laser designed to produce pulses of light about one picosecond long. Unlike most lasers, which use mirrors to confine light to the laser cavity, an optical fiber laser uses a loop of fiber as its cavity. A section of fiber doped with erbium serves as the gain medium. Strait and his students pump the gain medium with 1.06 µm light and it lases at 1.55 µm, conveniently the same wavelength at which optical fiber is most transparent and therefore most suitable for telecommunications. The eventual goal is to study how these short pulses propagate in optical fiber.

In January, Paul Crittenden ’04 joined Strait to work with the fiber laser and plans to complete an honors thesis next fall. During the summer of 2003, both Matt Spencer ’05 and Paul will work in the Strait lab.

In the fall, Professor William Wootters taught a new course, Seminar in Modern Physics (PHYS 151), which is designed for first-year students with unusually strong physics backgrounds. He also joined Professor Susan Loepp in co-teaching for a second time the interdisciplinary course Protecting Information: Applications of Abstract Algebra and Quantum Physics (MATH/PHYS 316). Loepp and Wootters are in the process of writing a textbook for their course, to be published by Cambridge University Press.

On the research side, Wootters worked with Naila Baloch ’03 and Sarah Iams ’04 on independent research projects: Naila studied the subadditivity of entropy, while Sarah explored the mathematics of maximally symmetric quantum measurements. Wootters also supervised Kate Gibbons ’03 in her thesis project on phase space representations of discrete quantum systems, which Gibbons and Wootters are currently writing up for publication. In the summer of 2003, Wootters will be working with John Mugno ’05, Josh Cooperman ’05 and Matt Hoffman ’04 on three research projects in quantum mechanics.

Assistant Professor Dwight Whitaker taught Introductory Quantum Mechanics (PHYS 301) in the fall term for the second year. In the spring, he taught The Physics of Everyday (PHYS 100) which featured Whitaker and some students walking across hot coals as part of a student group research project. During winter study, he taught Electronics PHYS 015 s.

During the summer of 2002, Prof. Whitaker worked with Leon Webster ’04, Jed Doench ’04, and thesis student Naim Majdalani ’03 on constructing a Magneto-Optical Trap (MOT) of rubidium-87 atoms. The MOT contains approximately 1 billion rubidium atoms at a temperature of a few hundred microKelvin. During the academic year, Naim and Whitaker worked towards transferring these cold atoms into a dipole trap where they can be further cooled to form a Bose-Einstein Condensate (BEC) - a new form of matter where quantum mechanical nature of the atoms becomes apparent. At extremely low temperatures, these clouds of atoms will begin to behave like one “super-atom” rather than as a collection of individual particles.

This summer his lab will continue towards making a BEC with the help of Justin Brown ’05 and thesis students Leon Webster ’04 and Sarah Iams ’04. In the spring of 2003, Whitaker was awarded a $45,000 grant from the Research Corporation to support this research. He will also be working with Zachary Kung ’04 to update the laboratories in PHYS 301. Next year this course will feature a new lab to observe the hyperfine spectrum of rubidium atoms using diode lasers.

Staff Physicist and Coordinator of Science Facilities, Bryce Babcock, traveled to Hawaii in August 2002 with Professor Jay Pasachoff and a group headed by Professor James L. Elliot of MIT to participate in observations of Pluto’s atmosphere using several telescopes at Mauna Kea, These observations have led to an article in Nature in July 2003, and two other publications are in progress. He also collaborated with Professor Pasachoff on a total solar eclipse expedition to Ceduna, Australia in December 2002. (For further details regarding these experiments and other publications, see the Astronomy departmental and faculty publications sections.) In addition to his work developing research and instructional laboratory apparatus for the sciences, Babcock serves on the Animal Care, Safety, WilliamsScene and Science Executive Committees. He continues as editor of the Report of Science at Williams, the annual review of science activities at Williams, which is provided in both print and web-accessible versions.