Abstracts of Contributed Papers
October 25-26, 1996

1:30 pm - Comet Hale-Bopp - Pictures and Projections, David R. Renneke, Physics Department, Augustana College, Rock Island, IL 61201, dr@helios.augustana.edu

Discovered over a year ago well beyond the orbit of Jupiter, Comet Hale-Bopp promises a spectacular show next March and April. Items to be discussed and illustrated include its size, angular velocity, trajectory, location in the sky, recent jets, and several pictures. I will show several CCD images taken at or near Augustana College using an SBIG ST-6 CCD camera. I will also show a time-lapse movie of the comet and explain how it was created. The movie and many still pictures can be seen at our astronomy Web site: "http://helios.augustana.edu/astronomy".

Comet Hale-Bopp is promising to light up the skies of 1996 and 1997. Already, in the wake of last spring's Comet Hyakutake, the interest in the comet is running high. Expectations at this time are for Hale-Bopp to outshine Hyakutake are reasonable. Though comets are much like cats in that they have tails and do precisely as they will, nearly everyone will want to know how to find Hale-Bopp. The presenter will discuss when and where to look for this celestial interloper.

2:10 pm - Studying Musical Instruments with Electronic Holography, Thomas D. Rossing, Physics Department, Northern Illinois University, DeKalb, IL 60115

Although holograms recorded on film have high resolution, it is much more convenient to create the holographic images electronically, so that they can be viewed as soon as they are created. TV holography or electronic speckle pattern interferometry allows real-time fringes to be presented on a video monitor without any photographic processing. Modern TV holography systems use sensitive CCD cameras, and they incorporate image processing using microcomputers and techniques such as phase stepping. We are currently applying it to our studies of vibrations in cymbals, bells, and violins, and we are happy to consider collaborative research on other types of structures.

The vibrational modes of a violin constructed by Carleen Hutchins have been studied using electronic (TV) holography. The observed modes are only in partial agreement with those observed in the same violin by Marshall (J Acoust. Soc. Am. 77, 695 (1986)) by modal analysis, but they compare favorably with holographic investigations on other violins. Because of its excellent spatial resolution and its convenience, electronic holography is a useful method for clearing up some of the confusion that has existed about violin modes, especially in the low-ftequency range.

We have used both electronic holography and experimental modal testing methods to study the vibrational modes of Malmark handbells tuned to G3, G4, and G5 . There is good agreement between the results of the two methods, although each one brings out certain features of the bells. Sound spectra reveal a surprisingly large contribution from the (2, 1) mode, especially in the larger bells, which falls more than 3 octaves above the fundamental. Strengths of the higher harmonics can be controlled by changing the clapper hardness and placement.

The emphasis of this summer project explores the use of a holographic technique to rewind and display images from a student microscope and describes a student built compact green laser used to assist in the continued study of holography.

3:30 pm - The Miniaturization of a Time of Flight-Mass Spectrometer for Infield Applications, Bridget Ford, Bradley University, Peoria, IL 61625.

The time of flight mass spectrometer (TOF-MS), due to its simplicity in design lends itself to the miniaturization process. The objective of our project at Argonne, National Laboratory was to design a TOF-MS with the dimensions of 4 " x 7" x 11 " and a weight of 15 lbs. The system was to be capable of determining the chemical composition of both liquid and gaseous samples with a sensitivity of parts per billion and an analysis capability stemming from its connection to a lap top computer. The miniaturized mass spectrometer which used an Nd:YAG pulsed laser for photoionization, an election multiplier detector for ion multiplication, and a digital oscilloscope for signal averaging was designed and constructed. Several components of the TOF-MS, such as the sample inlet mechanism and cooling system are still in the design stage; however, the mass spectrornoter itself has been tested and proven functional.

Apparatus has been constructed to measure and control the concentration of Hydrogen Iodide gas. This gas will be adsorbed on the surface of particulates and the nature of the resulting bonds will be investigated,with Dissociative Resonance Raman Spectroscopy. In order to know the amount of HI flowing through the test cell, the transmittance of thw sample gas is measured with a spectrophotometer, A LabVIEW program records the spectrophotometer input signal, calculates the HI concentration, and Provides an output signal to thermoelectric cooling modules used to control the temperature of the HI bottle. The HI temperature is varied in order to affect the vapor pressure of the liquid and the resulting flow rate of HI gas through the system. This flow regulation system controls smaller amounts of gas with more precision and is less vulnerable to the corrosive effects of HI than commercially available alternatives.

We have reengineered the Hall effect experiment setup in our teaching laboratory with the new Pentium-based PC computers using a multi-purpose data acquisition board and LabWindows/CVI software as part of the efforts to modernize the upper-level undergraduate laboratories. The resistivity, mobility, magnetoresistance and other effects related to Hall effect of an n-type germanium sample are studied by varying the temperature from 77K to 360K.

Some crystal optics concepts such as birefringence* and dichroism can be demonstrated simply and effectively using a microwave beam on wood targets. Some of these experiments will be shown. *Am. J. Phys. 63, 762 (8), August 1995.

A report will be made on the activities of AAPT as it relates to the Illinois Section of AAPT.

Finding ourselves with two revised lab curriculums bemnd us, two ahead of us, and two directly on top of us, we are literally in the middle of a laboratory development project that willaffect 3200 student Per Year, both in our calculus-based and non-calculus- based sequences. We report on our progress as well as what we have learned along the way.

Two Year Colleges in the Twenty-first Century, Breaking Down Barriers (TYC-21) has been in existence for approximately two years. Involvement of two year college physics faculty has been very good, with most regions meeting twice a year. A review of TYC’s mission will be presented along with a summary of past regional and national meetings. Lastly, objectives for future meetings will be discussed.

The critical need to produce scientifically literate citizens has been the major thrust of science education reform. The overworked teacher finds him/herself hard pressed to keep up with the rapid pace of scientific discoveries. With easy to use presentation software like PowerPoint and access to the world wide web through the Internet, science teachers can create vividly illustrated presentations using images and professional commentary available from web pages specifically designed for amateur scientists, educators, and students. This approach was used by the astronomy instructor at John Wood Community College to bring the latest breaking discoveries to his students.

We have developed a new multidisciplinary course for undergraduates called "Methods of Computational Science". This course is designed to introduce students to important algorithms for solving problems in physics and chemistry, with a focus on specific applications. Examples include the Runge-Kutta technique for solving ordinary differential equations (such as Newton's equations of motion or chemical kinetics equations), molecular dynamics simulations of two-dimensional argon clusters using the Verlet algorithm, and Monte Carlo studies of phase transitions in a 2D Ising model. We will also discuss the role of this course within a multidisciplinary program in computational science being developed at Illinois State University.

The rising air stream acquires its vorticity due to viscosity of air and the westward component of the velocity due to Coriolis force. The inclined air stream column causes the pressure gradient, which in turn results in subsidence in the rear and entrainment in the front, causing the system to move under the influence of ever present Coriolis force, changing its direction northwest to north and to northeast until it fizzles out eventually.

Focusing on a conceptual approach to problems when introducing new material, while avoiding reference to equations, can lead to important insights into student misconceptions and misunderstandings. These insights allow the teacher to address issues which make some problems mysteriously difficult for many students. The classroom methodology will be described along with several anecdotes which illustrate the insights to be gained. A source of prepared materials for teachers will also be supplied.

10:05 am - Relativistic Effects of a Classical Electron in an Electromagnetic Radiation Pulse*, Jason C. Csesznegi, Department of Physics, Illinois State University, Q. Su and R. Grobe, Advisors.

Effects of relativity can be practically ignored when dealing with the motion of everyday objects. When dealing with very small objects, such as an electron on the other hand, the large speeds make the effects of relativity very apparent. These effects can be observed by the response of an electron to an electromagnetic radiation pulse, generated by a laser. * Supported by NSF grant #9631245, Res. Corp grant # CC4089, and ISU Honor's program

The recent theoretical progress in the area of interaction of atoms with intense laser fields will be reviewed in this talk. In a super-strong field, the rate of depletion of the atom due to ionization can actually decrease with an increase of laser field strength. Recent numerical experiments have predicted the occurrence of ionization revivals which are periodic occurrences of intensity regimes in which atoms are unstable. A computer simulation program was designed using classical mechanics to explore this regime. * Supported by NSF grant # 9631245, Res. Corp grant #CC4089, and ISU Honor's program.

We propose to explore the dynamics of electron wave-packets in intense laser fields spatially and temporally resolved. In the range of intensity we will look at (~1019 W/cm2), the corrections of special relativity become important. We will analyze wave packets in this regime by solving numerically the Dirac equation. * Supported by NSF grant # 9631245, Res. Corp grant #CC4089, and ISU Honor's program.

In recent years it was predicted theoretically and later verified experimentally that laser pulses can protect themselves from unwanted losses as they propagate through an absorbing medium. We have explored the propagation of two laser pulses that have different frequencies and found that atomic resonances are not important in maintaining the stability of these pulses. * Supported by NSF grant # 9631245, Res. Corp. grant # CC4088 and ISU Honor's program.

Recent theoretical studies predicted that the stability of the atom can grow with the intensity of the applying laser field. The nature of such a stabilized atom has been associated with the formation of a highly localized and spatially distorted state induced by the laser field. In this project we will examine the properties of these distorted states using a weak tunable laser. * Supported by NSF grant # 9631245, Res. Corp. grant # CC4089 and a URG from ISU.

The relatively mundane damped harmonic oscillator is found to exhibit interesting motion once under the influence of both a velocity dependent and coulomic frictional damping force. Data for the decay of the amplitude as a function of time were collected on a specially prepared torsional oscillator with a variable electromagnetic damping mechanism. An analytical solution of the appropriate equation of motion was obtained by the method of Laplace transforms. In both the limits of zero coulombic friction and zero velocity damping, the solution reduces to the well-known answers to the problem. The solution, when plotted with the correct parameters, fits the experimental data very well.

11:35 am - Presentation of Undergraduate Research Prizes and Certificates.

11:40 am - Preparing Students for Outreach, Curtis Shoaf and Mats Selen, University of Illinois, Urbana, IL 61801.

In order for Physics Van, an outreach program, supported by the University of Illinois, to remain successful, it is necessary to continually train students. The goal of this project is to prepare students each year so that the outreach has qualified individuals to effectively perform each show This training must be done in such a way so as not to diminish interest in the program. Hands on training with smaller groups provides students with the necessary experience while maintaining a high level of interest. This experience is beneficial to both the audience and the students involved. Many students gain knowledge and skills that prove to be propitious to their future endeavors.

In recent years, physics education researchers and cognitive psychologists have turned their attention to the question of how individuals solve basic physics problems. This talk is a presentation of a case study in which three experts and three novices were observed as they solved kinematics problems using a "think aloud" protocol. Follow-up interviews and content analysis lead the researcher to concluded that expert problem solvers do not always follow the most efficient routines, nor do they always use the most effective methods for teaching basic problem-solving skills to students.

In the summer of 1995, a group of college physics teachers met for a week at Lee College in Texas in order to develop a collection of questions for use as an instrument to measure student's conceptual understanding in the areas of electricity and magnetism. This report will deal with some of the preliminary results of these efforts.

We present here the photometric light curve analyses of the eclipsing binary star DN Auriga. The CCD photometry, performed at the Behlen observatory using the 0.76 m automated telscope gave 647 individual data points in V and R bandpass filters. From this data we have determined a new epoch and an orbital period of 0.6168891 days. The published spectral classification is F3. The Wilson-Devinney model was used to derive the photometric solutions. DN Aur is a W UMa type contact binary system. The mass ratio, (q = m2/m1 = 0.209), where star I eclipses at the primary minimum) suggests that the system has A-type cnofiguration. The computed light curve has a third light of about 22% and a total eclipse in the secondary minimum. A solution with a cold spot on the secondary component is also found. We recommend spectroscopic study of DN Aur even though calculations show it to be a single line spectroscopic system. Generally contact systems of spectral type F3 have periods ranging from 0.25 to 0.5 days. The large period of CN Aur suggests that it is an evolved contact system with case-A mass transfer.