Conference Workshops

Below you will find a listing of the conference workshops listed by title. Please click on the title of the workshop to view its description.

25-30 minute workshops with small groups

Compton Scattering
Faculty or Staff, University of Michigan

The scattering of X-rays by electrons was discovered by A. H. Compton in 1923. From careful measurements of the spectrum of scattered X-rays he showed that they suffered a shift to longer wavelengths. The size of the shift depended on the angle of scatter, and could be calculated by considering the process as a collision between a single photon and a single electron in which energy and momentum were conserved. The effect provides a striking demonstration of an electromagnetic wave behaving like a beam of "particles". The main purpose of this experiment is to observe the effect of gamma rays being scattered by material, and to measure their energy shifts as a function of their scattering angles.

Faraday Effect
Faculty or Staff, University of Michigan

This experiment allows the measurement of the effects of a magnetic field on the polarization of light (laser beam) propagating through a solid medium. A new experimental setup that uses modern rare earth magnets will be presented. The use of lasers of various frequencies enhances the pedagogical value of the setup. The experimental setup was developed by Professor Carl Akerlof at The University of Michigan.

Mass Spectrometry: Quadrupole Mass Filter
Faculty or Staff, University of Michigan

The mass spectrometer is essentially an instrument that can be used to measure the mass, or more correctly the mass/charge ratio, of ionized atoms or other electrically charged particles. Mass spectrometers are now used in physics, geology, chemistry, biology and medicine to determine compositions, to measure isotopic ratios, for detecting leaks in vacuum systems, and in homeland security. The first mass spectrographs were invented almost 100 years ago by A.J. Dempster, F.W. Aston, and others, and have been in continuous development ever since. However, the principle of using electric and magnetic fields to accelerate and establish the trajectories of ions inside the spectrometer according to their mass/charge ratio is common to all the different designs. Dempster's original mass spectrograph is a simple illustration of these physical principles.

In practice, it is difficult to achieve very stable and spatially uniform magnetic fields, especially with permanent magnets. These difficulties can lead to degradation of the mass resolution and drifts in the calibration of the instrument. In addition, the presence of stray magnetic fields can affect other instruments that may be used in conjunction with a mass spectrometer, for example, electron energy analyzers. In the early 1950's it was realized, by W. Paul (shared Nobel Prize in Physics, 1989) that use of magnetic fields could be eliminated altogether by a clever design which uses alternating quadrupolar electric fields rather than magnetic fields, hence the name Quadrupole Mass Spectrometer. This is the design that is currently in widespread use for residual gas analysis. It is highly stable and has excellent mass resolution. With high sensitivity electron multipliers, it can measure partial pressures down to 10-14 Torr! The operation of the Quadrupole Mass Spectrometer (QMS) is not quite so simple to understand as the magnetic sector design, but it is extremely elegant and involves some beautiful mathematics, and therefore the details are worth appreciating.

Magneto-Optical Trap
Georg Raithel, The University of Michigan

In this experiment on the magneto-optical trapping (MOT) of Rubidium atoms, students learn the principles of MOT operation. In the first phase of this lab, students develop the following skills: (1) Locking of the trap laser to a suitable frequency within the Rb saturation spectrum, (2) Alignment of the six trap laser beams through the MOT chamber, and (3) development of strategies to determine correct combinations of magnetic-field polarity and laser polarizations. In the second phase, students observe and record the MOT loading curve, that is, the MOT population as a function of time elapse after turning on the trap. From the loading curves, three important parameters associated with the MOT are determined: (1) the loading rate associated with the MOT growth, (2) the characteristic time constant of the MOT, and (3) the total number of atoms trapped. The characteristic time constant equals the average dwell time of a trapped atom in the MOT before it is lost due to collisions.

Blackbody Radiation and the Solar Surface Temperature
Faculty or Staff, University of Michigan

The basic goal of this experiment is the determination of the solar surface temperature from the relative intensities of the spectrum sampled at a number of wavelengths from 450 to 880 nm. The sampling is determined by a set of broadband interference filters that modulate the light intensity measured by the photocurrent in a reverse biased silicon diode. If the detailed characteristics of the filters and photodiode were all initially well known, a single set of measurements of sunlight through the filter set would suffice. In the absence of such information, the light from a tungsten lamp at different temperatures will be used to establish the appropriate calibrations. In addition, sunlight is also reddened by the atmosphere, which differentially absorbs the blue end of the spectrum. This effect can be corrected by measuring the spectral intensities as a function of zenith angle. Finally, least squares techniques determine the solar temperature by modeling the data with the Planck spectral distribution function. The experimental setup was developed by Professor Carl Akerlof at The University of Michigan.

Positron-Electron Annihilation
Faculty or Staff, University of Michigan

This experiment attempts to explore several features of positron-electron annihilation. One of the attractive aspects of e+-e- annihilation is the relative simplicity of the interaction. To first order, the two-body system decays into two back-to-back photons, each carrying an energy of mec2. This feature has provided the basis for a medical imaging technique called Positron Emission Tomography (PET). PET is often used in conjunction with other tomographic techniques, such as MRI, to image potentially cancerous tumors in which exploratory surgery is particularly hazardous. In condensed matter, the interactions between positronium and the substrate can provide information about the details of the substrate structure via the effects on the momentum distribution at the instant of annihilation. The angular distributions measured in this experiment will be used to estimate the typical momenta associated with these systems. This is not quite trivial because the angles are typically of the order of a few milliradians(fractions of a degree).

The source for positrons in this experiment is a radioactive source, Na-22, with an activity of about 5 µCi. Na-22 has a half-life of 2.6019 years and decays with the release of 2,842.3 keV of energy. In 90.3% of the decays a ß+ is emitted with a 545.7 keV maximum kinetic energy followed by a 1,274.5 keV gamma-ray transition to the Ne-22 ground state. Approximately 0.06% of the time, the ß+ emission bypasses the excited state and directly transitions to the Ne-22 ground state. About 10% of all decays proceed by electron capture instead. The total energy budget is satisfied by including the 511.0 keV rest mass energy carried off by the sodium valence electron that is now unbound.

Raman Spectroscopy
Faculty or Staff, University of Michigan

When light is scattered from a molecule or crystal, most photons are elastically scattered. The scattered photons have the same energy (frequency) and, therefore, wavelength, as the incident photons. However, a small fraction of light (approximately 1 in 107 photons) is scattered at optical frequencies different from, and usually lower than, the frequency of the incident photons. The process leading to this inelastic scatter is termed the Raman effect. Raman scattering can occur with a change in vibrational, rotational or electronic energy of a molecule. If the scattering is elastic, the process is called Rayleigh scattering. If it's not elastic, the process is called Raman scattering. Raman scattering (or the Raman effect) was discovered in 1928 by V. C. Raman who won the Nobel Prize for his work. If the substance being studied is illuminated by monochromatic light, for example from a laser, the spectrum of the scattered light consists of a strong line (the exciting line) of the same frequency as the incident illumination together with weaker lines on either side shifted from the strong line by frequencies ranging from a few to about 3500 cm-1. The lines of frequency less than the exciting lines are called Stokes lines, the others anti-Stokes lines. Raman spectroscopy is very important practical tool for quickly identifying molecules and minerals. A Raman spectrometer was deployed on the Viking landers in 1972 and in other missions. Raman spectroscopy also has important scientific applications in studying molecular structure. In this experiment we will study both kinds of applications. A set of real, man-made, and optically equivalent diamonds will be provided as a final project.

Transmission Electron Microscope
Faculty or Staff, University of Michigan

In this experiment we will explore the use of transmission electron microscopy (TEM) to take us into the world of ultra-small structures. This is the regime between 1000 Å and atomic dimensions in which the continuing miniaturization of integrated electronics is being pursued. It is also a very important region for structural biology. These length scales are far below the limit where the resolution of conventional optical microscopy becomes dominated by the wavelength of visible light (~5000 Å). The transmission electron microscope (or TEM), first invented in the late 1930's, has now developed into the technique of choice for micro-structural studies in a wide range of fields: materials research, biophysics, polymer science, mineralogy, and health sciences, to name a few.

In the first part of the experiment, you will get a feel for the capabilities and immense resolving power of TEM by imaging some samples of DNA. We will measure the diameter and pitch of DNA's famous double-helix structure. In the second part of the experiment, we will use TEM to study some "quantum well" structures made from ultra-thin layers of Silicon and alloyed Silicon-germanium. We will determine the point spread function of the Philips 420 electron microscope and measure, at the highest magnification, the width of a quantum well and the abruptness of its boundaries. These are key quantities that determine the spectrum of electronic energy levels of the quantum well. The Si/Si-Ge samples will also demonstrate the capability of TEM to obtain selected-area diffraction patterns, from which detailed structural information can be obtained at atomic dimensions.

X-Ray Spectroscopy
Faculty or Staff, University of Michigan

The discovery of x-rays by Roentgen in 1895 in many ways marks the dawn of modern physics. The short wavelength end of the electromagnetic spectrum represented by x rays and g rays is of great practical importance as a probe of the internal structure of matter, as a diagnostic tool in medicine, and as a window into cosmic processes such as supernovae and black hole accretion. In this experiment you will use a precision solid-state detector to study x-ray energy spectra of x-ray from a number of sources. Nuclear x-ray sources are used to calibrate the device to high precision. Then, bombardment from an alpha source is used to stimulate atomic x-ray transitions in a number of materials. The x-ray energies reveal the atomic level spacings with great clarity, and can be used to show the existence the atomic number. The characteristic x-ray lines of the elements are then used to determine the composition of unknown samples. There will be a surprise source of x-rays that will delight you and your students!

Nonlinear Motion
Robert DeSerio, University of Florida

A chaotic pendulum apparatus, Am. J. Phys. 71, 250-257 (2003), and an electronic chaos apparatus, Am. J. Phys. 72, 253-258 (2004), will be demonstrated with interfaces for a stepper motor, rotary encoder, and electronic chaos circuit plainly visible on a standard breadboard. Software for simulating the apparatus, for acquiring and displaying data, and for calculating fractal dimensions, Lyapunov exponents, and system parameters from the data will be presented.

Robert DeSerio, University of Florida

Simple data acquisition programs and electronic circuits will be available to demonstrate the low-level interfacing to a stepper motor, Pasco rotary encoder, Pasco motion sensor, and electronic chaos apparatus.

Mössbauer Effect
Van Bistrow, University of Chicago

Participants will be shown the Mössbauer Effect experiment done at the University of Chicago.

Students typically measure

  • the natural line width of a nuclear transition
  • nuclear Zeeman splitting
  • magnetic quadrupole splitting of nuclear energy levels
  • chemical shift of nuclear energy levels
The Austin Scientific apparatus consists of a magnetically driven rod, which moves a Co-57 source with a constant acceleration.  The resulting Doppler-shifted Co-57 photons have a range of energies which span the resonant absorption energy of nuclei in a stationary absorber.  Photons not absorbed by the stationary nuclei are detected in a proportional counter.  Students use a laser and Michelson interferometer to determine the velocity of the source at each point in the spectrum.

A multi-channel analyzer/multi-channel scaler is used to obtain and display the Mössbauer spectra. Various absorbers are provided, placing the Co-57 nuclei in a variety of lattice environments. We hope to show the participants one technique for obtaining Mössbauer spectra and a start on their interpretation.

Optical Pumping A

To facilitate real comfort with both the physics and the apparatus, we have limited the sessions to groups of 3, and created double sessions. We strongly recommend that you sign up for both A and B sessions.

Optical pumping is a non-laser way to use light, interacting with atoms in the vapor phase, to 'pump' the atoms into states that permit the observation of radio-frequency quantum transitions between energy levels of the atoms' ground states. This experiment is a fine illustration of the polarization properties of light, the energy-level structure of atoms' ground states, and the Zeeman effect of external magnetic fields on these atomic energy levels.

Participants will see, at level A, Introduction to Optical Pumping

  • a hands-on familiarization with the parts of the apparatus, and instruction on how to align it for operation
  • magnetic-field sweeps through zero (total) field, in the presence of the earth's ambient field, and detection of the 'zero-field resonances'
  • optimization of the zero-field resonance, and detection of its width; also application of the resonance to the detection of magnetic-field fluctuations

Optical Pumping B

Available only to those who have taken session A.

For abstract, see above in 'Optical Pumping A'.

Participants will see, at level B, More on Optical Pumping

  • radio-frequency resonances, induced by the addition of a radio-frequency magnetic field (of frequency 10 - 100 kHz), and the dependence of the resonances' location and size on the frequency and amplitude of the r.f. fields
  • the Zeeman effect, in the dependence of the resonance's location on the strength of the steady magnetic field

Pulsed NMR (nuclear magnetic resonance) A

To facilitate real comfort with both the physics and the apparatus, we have limited the sessions to groups of 3, and created double sessions. We strongly recommend that you sign up for both A and B sessions.

Nuclear magnetic resonance is a tool that allows the interaction of external radio-frequency magnetic fields with the magnetic moments of the nuclei found in ordinary liquids. In this workshop offering, participants will work on TeachSpi's new PS2-a, a tabletop, permanent-magnet, pulsed-NMR system that will display all the basic features used in modern pulsed-NMR technology.

Participants will see, at level A, Introduction to pulsed NMR

  • a working PS2-a unit, configured for pulsed (rather than cw) operation on proton (rather than 19F) nuclei
  • familiarization with the permanent magnet and its temperature stabilization, and the sample-holder and its 'tuning' for optimal operation
  • installation of a sample, and detection of the pulsed-NMR signal, and its optimization by electronic gradient cancellation
  • measurement of the nuclear resonant frequency, and the inference of the magnetic-field strength, to 6-digit precision
  • variation of the signal with pulsed-rf amplitude and duration, and an interpretation in terms of rotation of a spin vector on the Bloch sphere

Pulsed NMR (nuclear magnetic resonance) B

Available only to those who have taken session A.

For abstract, see above in 'Pulsed NMR A'.

Participants will see, at level B, Advanced topics in pulsed NMR

  • methods for measuring T1, the 'spin-lattice relaxation time'
  • the simplest spin echo, and its near-immunity to magnetic-field imperfections
  • multiple-pulse spin-echo sequences
  • methods for measuring T2, the 'spin-spin relaxation time', in the presence of gradients
  • (as time permits) Fourier methods, and the detection of chemical shifts

Modern Interferometry A

To facilitate real comfort with both the physics and the apparatus, we have limited the sessions to groups of 3, and created double sessions. We strongly recommend that you sign up for both A and B sessions.

The 'Modern Interferometry' set-up available from TeachSpin offers a tabletop-sized optical breadboard, and all the components required for students to lay out, build, and apply a variety of interferometer topologies. In the Workshop, participants will be guided through the actual assembly, alignment, and use of one such topology -- the Michelson interferometer.

Participants will see, at level A, Introduction to Interferometry

  • an optical table with laser and alignment system installed
  • how to lay out, assemble, and align a Michelson interferometer
  • how to detect 'fringe formation' visually, and how to optimize alignment
  • how to understand 'interferometric sensitivity', and its implications for vibrational effects
  • how to add a photodetector, for the high-speed detection of signal variation

Modern Interferometry B

Available only to those who have taken session A.

For abstract, see above in 'Modern Interferometry A'.

Participants will see, at level B, Applications of Interferometry

  • how to make controlled and measureable sub-micron displacements of one mirror in the interferometer
  • how to process fringe signals electronically, and how to 'count fringes', in order to measure the wavelength of light directly with a micrometer
  • how to derive an experimentally-measured value of the wavelength of light

Diode-laser Spectroscopy A

To facilitate real comfort with both the physics and the apparatus, we have limited the sessions to groups of 3, and created double sessions. We strongly recommend that you sign up for both A and B sessions.

Modern diode-laser technology makes it possible to realize on a tabletop the ideal of a monochromatic, yet tuneable, source of collimated light waves, in the form of a laser beam of many mW of power, and well under 10 MHz of optical linewidth, near a frequency of 384 million MHz (near wavelength 780 nm in the near-infrared). This laser radiation can resonate with an optical transition in atoms of rubidium, conveniently available in the vapor phase in glass cells near room temperature. The result is a system in which the fundamentals of the resonant interaction of light and atoms can be studied in exquisite detail.

Participants will see, at level A, Introduction to Diode-laser spectroscopy

  • how to activate a (temperature-stabilized) diode-laser system; how to detect the (invisible) beam, and how to reach threshold and operating points of the laser
  • how to make the laser beam interact with an atomic vapor, and how to image the fluorescence that occurs when the laser is properly tuned
  • how to use a piezo-electric drive to tune the diode-laser source, and how to display the effect of 'scanning' the laser frequency over the atomic resonance(s)
  • how to use a non-imaging photodetector to display the absorption (as well as the fluorescence) by the atomic sample
  • how to use a slow scan to show the absorption and fluorescence are correlated properties
  • how to use the spectroscopy system to infer the 'Doppler width' of the atomic transitions observed

Diode-laser Spectroscopy B

Available only to those who have taken session A.

For abstract, see above in 'Diode-laser Spectroscopy A'.

Participants will see, at level B, Advanced diode-laser spectroscopy

  • how to set up a 'pump-probe' experiment in rubidium vapor
  • how to use differential probe absorption to isolate the effects of pump light
  • why Doppler-free signals result, and what Doppler-free signals reveal
  • why there are more peaks observed than expected, and what 'crossover transitions' are

Two-slit interference, one photon at a time A

To facilitate real comfort with both the physics and the apparatus, we have limited the sessions to groups of 3, and created double sessions. We strongly recommend that you sign up for both A and B sessions.

Young's experiment of two-slit interference is a very convincing demonstration of the wave properties of light, and it makes possible a direct measurement of the wavelength of light. In this version of the experiment, a special apparatus makes it possible to perform Young's experiment at a level of light intensity so low that light can be thought of as passing through the apparatus 'one photon at a time'. Yet despite the detection of light at the single-photon level, displaying the particulate nature of light, the interference of the light persists, and the wavelength of the light can still be measured.

Participants will see, at level A, Quantitative Two-slit Interference

  • how to 'open the cover' of the apparatus, and identify all of its parts
  • how to use a laser light source to trace the transport of the light from entrance slit, to double slit, to exit slit; how to use the 'slit-blocker', and how to move the exit slit
  • how to see the regime of single-slit diffraction, and how to see the emergence of the two-slit interference
  • how to use a photodiode system to map the two-slit interference signal quantitatively; and how this permits wavelength measurement

Two-slit interference, one photon at a time B

Available only to those who have taken session A.

For abstract, see above in 'Two-slit interference, one photon at a time A'.

Participants will see, at level B, Single-Photon Two-slit Interference

  • how to replace the laser source by a bulb, and the photodiode detector by a photomultiplier tube, to get into the single-photon mode of operation
  • how to hear, and to see, the count rate of single-photon events
  • how to map out the interference signal that remains visible in the single-photon mode of operation
  • how to estimate the 'number of photons in the box' in the 'single-photon' mode

Quantum Analogs A

To facilitate real comfort with both the physics and the apparatus, we have limited the sessions to groups of 3, and created double sessions. We strongly recommend that you sign up for both A and B sessions.

The wave equation for the propagation of sound in air inside structures, and the Schrödinger Equation for electron waves in space, share many mathematical features. This apparatus is aimed at building intuition about solutions of the fundamental equation of wave mechanics via hands-on encounter with analogous features in the properties of sound waves in air. The experiments are conducted using sound waves of ordinary (1 - 10 kHz) frequencies, produced and detected by ordinary speakers and microphones, inside metal-walled resonant systems. In particular, participants may choose the general area of either resonant modes inside an spherical cavity, or resonant modes in a periodic 1-dimensional system. The analogous features in quantum mechanics are the spherical harmonics that emerge in any spherically-symmetric system, and the 'bands and gaps' that appear in the mode structure for a 1-d spatially-periodic system.

Participants will see at level A, Introduction to Quantum Analogs

  • how sound waves are generated, detected, and quantified in the quantum-analogs system
  • how to set up 3-d spherical, OR 1-d spatially-periodic, acoustic 'testbad' systems
  • how to sweep in frequency, and how to identify normal modes of the acoustic system with eigenstates of the analogous quantum system
  • how to detect the angular structure of modes in 3-d space, OR how to see band and gap structure in the 1-d system

Quantum Analogs B

Available only to those who have taken session A.

For abstract, see above in 'Quantum Analogs A'.

Participants will see at level B, More on Quantum Analogs

  • how to explore the angular structure of mode patterns in 3-d space, and how they are connected with spherical harmonics
  • how to identify and change parameters in 1-d spatially-periodic systems, and how they are correlated with changes in the band structure that results

The Torsional Oscillator A

To facilitate real comfort with both the physics and the apparatus, we have limited the sessions to groups of 3, and created double sessions. We strongly recommend that you sign up for both A and B sessions.

The simple harmonic oscillator is perhaps the most central 'model system' in all of physics, and TeachSpin's 'Torsional Oscillator' is a fully-instrumented example of the harmonic oscillator. It permits an extremely wide variety of experiments, appropriate to instruction from introductory to graduate-level lab courses. The torsional oscillator can be calibrated and modelled in detail, it can be damped by three independent mechanisms, and it can be driven by arbitrary torque waveforms.

Participants will see, at level A, Intermediate torsional oscillations

  • where the 'spring' and the 'mass' are located in a torsional oscillator
  • how static, and oscillatory, properties of the oscillator can be deduced directly from experiment
  • how the separate angular-position and angular-velocity transducers work, and how they can be calibrated
  • how the 'torque drive' works, and how to calibrate and use it
  • how the linear-in-velocity damping works, and how to acquire, and to model, the damped-oscillatory decaying waveforms

The Torsional Oscillator B

Available only to those who have taken session A.

For abstract, see above in 'The Torsional Oscillator A'.

Participants will see, at level B, Advanced torsional oscillations

  • the simplest 'driven damped oscillations', and how to get, and to model, amplitude resonance
  • how to get, and how to model, the behavior of phase shift near resonance
  • how to understand the response to non-sinusoidal drive
  • how things change for other damping laws
  • coupled oscillators, energy interchange, and normal modes

Muon Physics

Cosmic-ray protons impinging on the upper atmosphere create showers of secondary particles, and the (relatively) long-lived muons resulting from pion decay reach the earth's surface to offer a free and reliable steady flux of fundamental particles for study. TeachSpin's 'Muon Physics' apparatus uses a single large scintillator, a photo-multiplier tube, and its associated electronics to make possible the study of muons' arrival. Happily, some muons come to rest in the scintillator, and decay within microseconds to produce a second detectable event.

Participants will see

  • how the configured apparatus produces a series of 'muon arrival events'
  • what a 'Poisson process' looks like, and what can be inferred from it
  • what a 'muon arrival followed by decay' event looks like, and how to measure muon survival time
  • how to histogram the measured muon survival times, and how to interpret this histogram
  • understanding mean life and half-life, and the lifetime for muons in matter

Atomic resolution imaging with the Scanning Tunneling Microscope
Mark R Flowers, Nanoscience Instruments, Inc

Participants will use the scanning tunneling microscope to image carbon atoms in highly ordered pyrolytic graphite (HOPG).  Experiment will demonstrate the setup of the easyScan STM, cutting an STM tip, and scanning HOPG to reveal the atomic lattice structure.  The atomic spacing will be measured.  Additionally, given more time, I/V curves will be demonstrated to show the quantum mechanical tunneling current dependence on voltage, and I/Z curves showing the tunneling current dependence on distance.

Measure surface forces with the Atomic Force Microscope
Mark R Flowers, Nanoscience Instruments, Inc

Participants will use the atomic force microscope to measure the adhesion forces between a silicon AFM probe and different materials.  The AFM can be operated in "Force-Distance" curve mode that allows very precise measurements of a microfabricated probe coming into contact with a surface and its subsequent retraction. Hooke's law is used to determine actual force. Materials with different surface properties will be investigated.

Introduction to nanoscale imaging with the Atomic Force Microscope
Mark R Flowers, Nanoscience Instruments, Inc

Participants will learn the basics of operating an Atomic Force Microscope by imaging nanoscale particles in both contact mode and dynamic force mode. This will include an introduction to how the AFM scans the surface and interprets interactions into 3D images. Software to measure cross-sections of nanoparticles will be demonstrated as well as additional off-line analysis of data.

Driven Damped Harmonic Motion
Ann Hanks, PASCO Physics

The amplitude vs. frequency curve is measured for a magnetically damped, sinusoidally driven, spring and mass system. The sweep of the driving frequencies is achieved using a computer and the signal output of the ScienceWorkshop 750 interface. The amount of damping can be varied to see how this affects the shape of the curve and the resonant frequency. Also, the phase relationship between the motion of the driver and the motion of the mass can be studied for the frequencies above, below, and at resonance. The simple addition of a point mass makes the system nonlinear, allowing studies of chaos.

Brewster's Angle
Ann Hanks, PASCO Physics

The index of refraction of nonconducting reflective materials can be determined by finding Brewster's Angle. In this experiment the percentage of polarized light reflected off the surface of the material sample is plotted as a function of the angle of incidence. The angle which gives the minimum reflection is Brewster's Angle. Curve-fitting is used to determine this angle precisely. But the question is: Can you see a difference in the index of refraction for different frequencies of light?

Gamma Spectroscopy
Roger Stevens, Spectrum Techniques

Nuclear half lives will be measured using the multichannel scaling feature of an MCA. Several sources will be used including a Cs-137 cow, filtered air, and a simple deposition from natural Thorium. The gamma spectrum from the Thorium deposition includes peaks from only a few of the isotopes of the decay chain.

Adiabatic compression of gases
Physics Enterprises

This workshop will demonstrate the use of the adiabatic gas law apparatus to verify various gas law relationships. Pressure-volume plots illustrating the ideal gas law, Boyle's law and the adiabatic gas law will be examined and the ratio of specific heat at constant pressure to constant volume (gamma) will be extracted. Pressure-volume plots of a complete cycle will be analyzed as well.

PS-15 Pulsed NMR
Joe Dohm, Tel-Atomic

Investigate nuclear magnetic resonance of protons with the PS-15 Pulsed NMR Spectrometer. Both spectroscopy and relaxometry experiments can be performed. By acquiring a signal of a free induction decay (FID) and performing a fast Fourier transform, spectra can be obtained capable of resolving chemical shifts of approximately 5 ppm. T1 (spin lattice) and T2 (spin spin) relaxation times can be measured. The presentation will focus on using TEL-Atomic's proprietary software to acquire and analyze a FID, and also on acquiring a spin echo sequence to measure T2. The PS-15 is a 15 MHz NMR Spectrometer with a .350 Tesla electromagnet. A block diagram is provided summarizing all connections between various components which are inside the unit (with the exception of the probehead and magnet).

CWS 12-50 Continuous Wave NMR/ESR Spectrometer
Joe Dohm, Tel-Atomic

Investigate nuclear magnetic resonance of protons, as well as electron spin resonance with the CWS 12-50 Continuous Wave NMR/ESR Spectrometer. Continuous wave NMR is the simplest method of investigating magnetic resonance. The magnetogyric ratio of protons will be calculated, and the qualitative difference between the spectra of solids and liquids will be discussed. The g-factor of electrons will be calculated.

Joe Dohm, Tel-Atomic

The TEL-X-Ometer is a useful platform that can be used to perform a wide variety of x-ray experiments. Bragg's law will be demonstrated using single crystals of several ionic compounds, such as NaCl and LiF (all face centered cubic). In addition, investigation can be made into Mosley's theory that every element is characterized by its atomic number. The TEL-X-Ometer is a compact and portable x-ray machine. X-rays can be produced at either 20 or 30 KV by an x-ray tube with a copper cathode. Operation of the TEL-X-Ometer can be automated with the TEL-X-Driver. Data is recorded onto a computer using TEL-Atomic's software.

Cavendish Balance
Joe Dohm, Tel-Atomic

The computerized Cavendish balance from TEL-Atomic will be demonstrated. The basic operation of the unit will be demonstrated, as well as sample data provided. The unit uses an innovative capacitive sensor to eliminate much of the noise associated with the traditional setup. Data is collected and analyzed via computer. In addition, a derivation is provided that allows the calculation of G from dynamic data, allowing the experiment to be completed in a single lab period.

Electrical Characterization of Photovoltaic Materials and Solar Cells with the Keithley Model 4200-SCS Semiconductor Characterization System
John Hayes, Keithley Instruments

The Keithley Model 4200-SCS provides a total system solution for DC I-V, C-V, and pulse characterization and stress-measure/reliability testing of a large variety of nanotech and semiconductor devices. This advanced parameter analyzer provides intuitive and sophisticated capabilities for semiconductor device characterization. The 4200-SCS combines unprecedented measurement speed and accuracy with an embedded Windows®-based PC and the Keithley Interactive Test Environment (KITE) to provide a powerful single-box solution.

In this workshop we demonstrate the broad capability of the 4200-SCS using a solar cell as an example device. Because of the increasing demand for energy and the limited supply of fossil fuels, much research is being done on solar or photovoltaic (PV) cells which convert light energy into useful electrical power. When the cell is illuminated, optically generated carriers produce an electric current when the cell is connected to a load.

Some of the electrical tests commonly performed on solar cells involve measuring current and capacitance as a function of an applied DC voltage. Capacitance measurements are sometimes made as a function of frequency or AC voltage. These measurements are usually performed at different light intensities and under different temperature conditions. A variety of important device parameters can be extracted from the current-voltage

(I-V) and capacitance-voltage (C-V) measurements, including output current, conversion efficiency, maximum power output, doping density, resistivity, etc. Electrical characterization is important in determining how to make the cells as efficient as possible with minimal losses."

Computed Tomography
Irwin Malleck, Klinger Educ. Prod. Corp. and Werner Bietsch, LD Systeme

The table top X-ray apparatus allows demonstrations of all major topics concerning basic and advanced applications of X-rays. The new computed tomography module, used with a Tungsten X-ray tube allows the user to perform introductory real time experiments with intensity and transparency control.

In this workshop the participants will perform a selection of experiments concerning the following topics:

  • Computed tomography of a frog and a LEGO house
  • Moseley's law and elemental analysis of coins with x-ray fluorescence
  • Compton effect on x-rays: Measuring of the energy of the scattered photons

NMR of a Flower
Irwin Malleck, Klinger Educ. Prod. Corp. and Werner Bietsch, LD Systeme

To demonstrate the advantages of various spectroscopic methods, e.g. in life sciences, the students can additionally perform introductory experiments of nuclear magnetic resonance. Experiments like NMR of a flower and hand crème (e.g. NIVEA) will enable the participants to understand the kind of opposite elemental sensitivity of x-ray spectroscopy and nuclear magnetic resonance spectroscopy on an introductory level.

How to optimize quantization of detector data by minimizing noise and improving signal fidelity when using a real time oscilloscope.
Marty Gubow, Agilent Technologies, Inc.

A real-time oscilloscope is a critical tool in the quantization of detector data. Modern tools can digitize at rates of 40GSa/s and achieve bandwidths that exceed 10 GHz. Unfortunately data can be distorted by poor signal fidelity and digitizer design. Scientists should understand the effects of inherent noise and digitizer error on their test data.

In this workshop we will explore:

  • Measuring oscilloscope noise floor and its effect on your measurements
  • Quantifying digitizer linearization
  • Limiting bandwidth to reduce noise
  • Advanced analysis techniques using MATLAB®
  • With transient or pulsed events how to maximize sample rate and record length by segmenting memory

Studies in using an Optical Trap
Ludwig Eichner, Thor Labs

An optical trap or an optical tweezers is a scientific instrument that uses a focused laser beam to provide an attractive or repulsive force, depending on the refractive index mismatch to physically hold and move microscopic dielectric objects. Optical tweezers have been particularly successful in studying a variety of biological systems in recent years. Studies in Brownian motion, the random movement of particles suspended in a fluid. Studies in Mie Scattering of particles relative in size as the wavelengths being scattered. Studies in Rayleigh scattering from molecules, describing the electrical charges on the molecule will move in an electric field. Calculating in trap forces, stokes oscillation and spectral density analysis may be calculated and analyzed.

Fundamental Studies in Polarization
Ludwig Eichner, Thor Labs

Polarization is a property of waves that describes the orientation of their oscillations. When light travels in free space it typically propagates as a transverse wave. Polarization occurs perpendicular to the wave’s direction of travel. The phenomena of polarization may be demonstrated in a series of experiments. Specific polarization effects in optical systems can be demonstrated with simple experiments. Polarization effects in reflection, refraction, scattering, circular polarization, and birefringence may be demonstrated.

MATLAB for Data Acquisition and Analysis
James Lockhart, San Francisco State University

Minimum preparation is completion of a MatLab tutorial (free).

This workshop will allow attendees to explore the use of MATLAB to acquire data from digital instruments and to perform several types of data analysis commonly used in advanced physics labs. We will run through basic statistical analysis, plotting, curve fitting, spectral analysis, and digital filtering. The use of graphical user interface tools such as cftool (curve-fitting tool), spectool (spectrum analysis tool), and dftool (digital filter tool) will be featured.

Lock-in amplifier Experiment
National Instruments

Thursday 20 minute sessions with focus on using the Lock-in to perform a couple of experiments (Harvard group?). One might be a demo experiment where you send an AC signal through a dark room, AC-modulated LED to photo-transistor receiver. Room lights are turned on and the lock-in does its job.

Ultrasound Imaging: a laboratory in sound, medical physics & imaging
Suzanne Amador Kane, Haverford College

Participants will be able to experiment with an apparatus designed to train physicians and medical physicists about the principles behind ultrasound imaging, as well as to use an actual medical imaging device to image a kidney "phantom" model. Laboratory manuals, purchasing information and other curricular information will be provided via a website to facilitate adopting this lab.

Single Photon Interference
Enrique Galvez, Colgate University

No description provided.

90 or so minute workshops with large groups

The bug: A temperature-controlled experiment on a protoboard
Paul Dixon, California State University at San Bernadino

We will develop and explore a fully-automated temperature-controlled experiment using inexpensive electronic components, LabVIEW and the NI-ELVIS platform. The core of the experimental system, which we call "the bug," is a simple three-component system made up of a thermistor, a resistor, and a ceramic (doped ferroelectric) capacitor bonded together. The thermistor and resistor combine to form the temperature measurement and control system. The ceramic capacitor is the component under study. The overall objective of the experiment is to measure its capacitance, and thus its underling ferroelectric behavior, as a function of temperature. This simple and inexpensive system allows for the exploration of a significant range of computer-based data acquisition and control topics. When fully integrated, this system mimics many of the common interfacing, acquisition, and control issues encountered in table-top condensed-matter physics experiments.

Participants will:

  • develop software to measure resistance, and to control and measure slowly-varying voltage signals
  • implement, tune, and test a software-based proportional-integral-derivative (PID) temperature controller capable of mK stability
  • develop software to generate and acquire buffered voltage waveforms in response to a variety of triggering conditions
  • implement and explore noise rejection techniques using signal averaging and synchronous triggering
  • implement a fully-automated and multi-threaded experimental control system based upon the previous exercises, using it to measure the underlying ferroelectric response of the capacitor versus temperature

NI-Elvis Advanced workshop
Paul Dixon and National Instruments

Minimum preparation is completion of 6-hour on-line LabVIEW tutorial (free).

Projects, from Hands On Introduction to LabVIEW, (Oxford Press, 2009)
John Essick, Reed College

Minimum preparation is completion of 6-hour on-line LabVIEW tutorial (free). Introductory and advanced using NI USB-6009. Participants will complete one or two of the following projects, depending upon each person's level of experience with LabVIEW.

  1. Digital Oscilloscope (Analog Input)
    • (optional) Use MAX to set-up DAQ device (Section 4.6, p132-136)
    • Build DC Voltmeter to acquire single voltage sample (Section 4.7, p136-144)
    • Construct Digital Oscilloscope with digital triggering (Section 4.8, p. 144-152). For help in making the Digitizing Parameters control cluster, see p104-105. The Unbudle By Name icon is explained on p. 107.
    • (optional) Use your digital oscilloscope to measure the time constant of an RC circuit as described in problem 5 on page 414.
  2. Thermistor-Based Digital Thermometer (Analog Input)
    • Thermistor's temperature-dependent resistance obeys the Steinhart-Hart Equation (Section 9.1, p. 304-306). For our thermistor, , , and .
    • (optional) To gain experience configuring the DAQ Assistant Express VI, build DC Voltmeter (Section 4.7, p. 136-144)
    • Construct the Digital Thermometer described on p. 330-331.
  3. Toggle Lighting of Two LED (Digital Output Lines)
    • Carry out Alternating LED project descibed on p. 168-169
  4. Spectrum Analyzer (Analog Input)
    • Build Frequency Calculator VI (Section 10.5, p. 343-345). For help in making the Digitizing Parameters control cluster, see p104-105. The Unbudle By Name icon is explained on p. 107.
    • Construct the Spectrum Analyzer described on p. 374-375. The required front panel and block diagram are shown on the back of this sheet.
    • (optional) Add Estimated Frequency and Amplitude (Section 10.14, p. 370-373) to your Spectrum Analyzer program.
    • (optional) Explore windowing (Section 10.13, p. 365-370) and/or aliasing(Section 10.15, p. 373-374) using your Spectrum Analyzer.