August 1994



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Daniel H. Reich

Many students beginning graduate study in experimental physics know very little about the techniques, lore, and art of the field in which they have chosen to work. For both the student and the advisor, the challenge is to get the student up the learning curve as quickly as possible so that he or she may begin to function as a productive member of the research group. The range of material the student must cover is extremely broad, from the relevant theory to the relevant vacuum pump. This knowledge is usually obtained through work in the laboratory, individual study, and interactions with other members of the group; hence, there is a risk that students may become too narrowly focused on their own work and learn little about how experiments are done outside their own laboratory.

This situation may be addressed in part by a classroom course in experimental techniques. This course can serve both as a means of passing on information about techniques used locally and as a means of imparting general knowledge about techniques used in a particular field. Such a course is often organized in a seminar format. One approach is to have a series of single lectures given by different faculty members about the techniques that they use. Another is to have the students themselves give the lectures. In Condensed Matter physics, perhaps the best known example of this latter approach took place in the low temperature physics group at Cornell in the early 1980s. The lecture notes from this course have been published, and are now one of the standard references on low temperature techniques [1]. At Johns Hopkins University, where the experimental Condensed Matter group consists of only four faculty and approximately fifteen graduate students, neither of these approaches is practical. What has proved to be effective, instead, is to offer a more formal course in Experimental Condensed Matter Physics with one professor taking the primary teaching responsibility. In teaching this course I have primarily targeted students in their first year of research. My goal has been to provide a basic underpinning of knowledge, and then to give some impression of the range of techniques available. In the first part of the course, I have concentrated in some detail on a few of the most basic and widely used techniques. These include transport measurements, vacuum technology, small signal ac measurements, cryogenics and low-temperature techniques, thermometry and temperature control, and statistical analysis and fitting of data. The middle part of the course contained lectures on more specialized topics, and in the last few weeks each student was asked to give a one-hour talk in this same vein. Examples of areas covered include electron spin resonance, molecular beam epitaxy, Auger spectroscopy, lithography, DC and RF SQUIDS, and small angle neutron scattering.

The most obvious problem that arises in teaching such a course is that it is very difficult to make an adequate presentation of a technique with which one has no direct experience. In this regard, this course would clearly benefit from team teaching. As this has not been possible to date, I have prevailed on interested faculty to serve as guest lecturers. One professor, for example, gave two lectures on neutron scattering and then organized a field trip for the students to the research reactor at NIST. Such additions need not come only from the experimentalists. A theorist gave a lecture on "computer experiments" done by Monte Carlo or molecular dynamics simulations that fit in very well. Another way of broadening the range of material covered is to have the students give their talks about techniques that they are using. This is particularly effective if senior students are enrolled, as they may be more well versed in the practical aspects of a given topic than the instructor.

Another challenge is to find appropriate reading material to supplement the lectures. Some sub-fields have a number of good reference books, but these tend to become dated as techniques evolve and new equipment becomes available. For some hardware topics, such as vacuum technology or the theory of operation of a lock-in amplifier, good introductory material may often be found in the catalogs and manuals provided by the manufacturers. For a broader perspective on a particular technique, an approach that works well is to find a scientific paper with an accompanying article in a journal such as Reviews of Scientific Instrumentation.

The students' reaction to the course has been very positive. They like the emphasis on the practical and feel that the course also served to broaden their perspective on experimental research. Judging by its success, this is a course that will probably become a standard part of the training of condensed matter experimentalists at Johns Hopkins.

[1] R. C. Richardson and E. N. Smith, Eds., Experimental Techniques in Condensed Matter Physics at Low Temperatures, Addison-Wesley, (1988).

Daniel H. Reich is an Associate Professor of Physics at Johns Hopkins University. He conducts research on superconductivity in artificially structured materials, and magnetism in low-dimensional systems.