u Detect and quantify Johnson noise, the ‘Brownian motion’ of electronsu Determine Boltzmann’s constant, kB, from temperature dependence of Johnson noiseu Observe and quantify shot noise to measure the fundamental charge ‘e’u Configure front-end low-level electronics for a variety of measurementsu Investigate ‘power spectral density’ and ‘voltage noise density’ and their V2/Hz and V/√Hz units

u Explore NMR for both hydrogen (at 21 MHz) and fluorine nucleiu Magnetic field stabilized to 1 part in 2 millionu Homogenize magnetic field with electronic shim coilsu Research grade measurement of T1 and T2

u Compare CW and FID signals from both protons and fluorineu Measure chemical shifts in inequivalent hydrogen and fluorine nucleiu Observe PNMR/CW NMR in soft solids

NOISE FUNDAMENTALS

FOURIER METHODS

PULSED/CW NMR SPECTROMETER

SR770 FOURIER ANALYZER(Stanford Research Systems)

ELECTRONIC MODULES(Fifteen Functional Circuits)

COUPLED MECHANICAL OSCILLATOR

FLUXGATE MAGNETOMETER

ACOUSTIC RESONATOR

u Learn frequency-domain analysis using a variety of frequency-space examplesu Use the unsurpassed frequency resolution, dynamic range, and versatility of the SR770u Carry out experiments on modulation, demodulation, and signal recoveryu Execute three ‘external experiments’ reinforcing frequency-space methodsu Explore the comprehensive instruction manual covering curricular activities, projects and mathematics

SHORT FORM CATALOG No. 12

Instruments DesIgneD for teachIng

Have you ever considered the under-representation of condensed-matter physics in the advanced lab? In an era of unprecedented technological application of solid-state physics, in a time when perhaps half of all physicists work in condensed-matter areas, does your advanced lab accurately reflect the importance of this area of physics? Reflections like these motivated a multiyear program at TeachSpin to develop Condensed Matter Physics (CMP) experiments. Rather than a set of individual instruments, we have created an apparatus collection that enables a whole set of experiments. Our debut offering includes apparatus that allows students to explore three fundamental areas in CMP: electrical transport, magnetic susceptibility, and specific heat. And our apparatus is designed to accommodate many more types of experiments – some of them our future developments, and some of them yours and your students’. We thought very carefully through the ‘parameter space’ we wanted to explore, agonizing first over the temperature range to cover. Because it can display so many physics phenomena while remaining both accessible and affordable, we settled on the 77 – 400 K range, provided at minimal cost-of-operation by using liquid nitrogen as a coolant. We also identified the need to work over the 0-1 atmosphere

range of pressure, and thought through the magnetic-field requirements necessary for both initial and future experiments. A centerpiece of our CMP initiative is an all-metal dewar vessel, custom-made for us by Janis. It includes a 2-liter LN2 reservoir, and an experimental ‘baseplate’ thermally linked to it, with baseplate temperature servo-controllable in the temperature range above 77 K. That baseplate is the arena on which experiments get mounted. The experiments, once mounted, are enclosed by an ‘inner can’ that permits them to operate at pressures ranging from vacuum to an atmosphere of a chosen gas. There is also a straight-shot mechanical access from above into that experimental space. Meanwhile, around that ‘can’ and the LN2 reservoir is an insulating space, designed to be held at vacuum. Our dewar is artfully mounted on pivots, permitting an easy mechanical inversion that allows convenient access to the experimental baseplate.

The Teachspin/Janis CMP dewar, mounted on its wooden base, with the outer ‘vacuum can’ in place; all vacuum and electrical feedthroughs are at the top.

The dewar, with its outer and inner cans removed, can be inverted on its base to allow easy access to the experimental ‘baseplate’ seen at the top of this image.

CONDENSED MATTER PHYSICS

Our dewar is also fully ‘connectorized’ – a total of 30 electrical leads pass though vacuum seals into the outer and inner spaces. Connections inside the dewar are made with press-fit and screw-terminalfittings – no soldering required. Similarly, without any need for any soldering, students will use our Cryostat Interface box to make reliable and traceableconnections between all the wires emerging from the dewar, and the external world of electronics.

TeachSpin has thought out the vacuum requirements, too. Some schools will already have access to pumping stations; others might want our suggested (oil-free, air-cooled, diaphragm/turbo-molecular) system. Either way, two industry-standard KF25 flanges form the interface between the vacuum ‘supply’ and the dewar ‘demand’. From a warm 1-atm start, our dewar has a pump-down time < 5 minutes; and once LN2 is added, a cool-down time < 1 hour.

Now to those three experiments we offer in our debut effort: Based on the system of dewar, vacuum pump, Cryostat Interface, and basic electronics, the three experiments can be bought separately. ELECTRICAL TRANSPORT enables measuring electrical resistivity and Hall coefficients in semiconductor samples. Here an obstacle we’re surmounting is the supply of samples – we’re initially supplying n- and p-type silicon samples, professionally photo-lithographed, gold wire-bonded, thermally-mounted, encapsulated and connectorized samples, with connections optimized for resistivity and Hall-effect experiments.

The magnetic field needed for semiconductor Hall-effect studies comes from a coil wound on a radiation shield mounted inside the dewar. As a bonus, these mounted samples also will fit into our new Room-Temperature Hall Effect

apparatus. With this stand-alone kit, the absolute sign and magnitude of the Hall Effect, both in silicon samples and in copper, can be measured.M A G N E T I C SUSCEPTIBILITY makes possible the measurement of the

susceptibility χ as a function of temperature. This CMP experiment builds on concepts introduced in our existing Foundational Magnetic Susceptibility apparatus. What’s new in the CMP context is a way to measure χ(T) over a factor-of-4 range in absolute temperature. Remarkable sensitivity to χ is provided by

an ‘a.c. transformer’ or Hartshorn-coil technique.

The Cryostat Interface box, shown with its cover to the side, to expose how wiring to/from the dewar can be managed, without soldering.

The CMP dewar at left, and a recommended vacuum-pump system atright, ready for use in the lab.

The Room-Temperature Hall-Effect apparatus: at upper right, a moveable permanent-magnet structure, and a CMP Si sample in place.

A TeachSpin CMP silicon sample (8x3 mm2) encapsulated on itsmount, with 8-pin connector at right.

We use lock-in detection to process the signals, and thereby also become sensitive to electrical conductivity (if any), in addition to sensing magnetic susceptibility. We provide a suite of samples with the experiment; and in addition, we empower students to create their own samples, using an epoxy-encapsulation technique.

SPECIFIC HEAT uses a vacuum heat-pulse calorimetry technique that measures the heat capacity of samples. Measurements using it will show, experimentally, that the classical Dulong-Petitclaim of the temperature-independence of the specific heat, cp(T), is false. The motivation, of course, is the investigation of Einstein and Debye models for specific heat. The investigation thus shows the applicability of quantum-mechanical principles to the thermal behavior of macroscopic bodies. The technique is also directly sensitive to phase transitions, if any, in the sample.

Here too, we provide a suite of samples, interesting for their temperature-dependent specific heat, and for various kinds of phase transitions. Again, our set-up will also accommodate student-created samples, either in solid or powder-in-epoxy form.

ELECTRONIC SUPPORT for these experiments, and for our dewar, is also part of our CMP development. Our vacuum system comes with the gauges required; our dewar comes with the temperature-stabilizing servo-mechanism, and the temperature-measuring transducers, that are required. We house the associated electronics in a Stanford Research Systems bin or ‘rack’ for SIMs (Small Instrument Modules), and we make use of modules both from TeachSpin and from SRS.

The SIM-bin also accommodates the proprietary electronic modules that come as parts of our individual experiments. Thus the low-level and custom analog electronics needed for the experiments you choose will arrive with your chosen apparatus.

SUMMARY: On a well-thought-through ‘platform’ of a dewaroptimized for use in the advanced lab, you can host, in turn, one of three experiments introducing your students to fundamental phenomena in condensed-matter physics. You might already have the vacuum system you’d need; you might start with just one of our three experiments on offer. See our website for details (and prices), and our collection of newsletters for samples (and sample data), to learn how TeachSpin hopes to address the under-representation of condensed-matter physics in the advanced lab.

The specific-heat experiment, showing at top a round white sampleclipped to the ‘addendum’, suspended above the baseplate.

The Hartshorn-coil structure, shownmounted on the dewar’s baseplate,with the inner can removed.

Stanford Research System’s ‘mainframe’ for SIMs, populated with electronicmodules from TeachSpin and SRS

Support electronics on optional TeachSpin shelving (at left) accompaniesthe CMP dewar (center) and recommended pumping system (at right) to create a laboratory system for condensed-matter physics fitting into 2 meters of table space.

• Measure magnetic susceptibility of solids, liquids and powders• Unambiguously distinguish dia- and para- magnetism• Verify properties exclusively predicted by quantum mechanics• Use first-principles calibration to get quantitative results• Detect magnetic susceptibility of water with S/N ≈ 10/1• Exploit Guoy method for straightforward and understandable data reduction

• Optimized for demonstrating the Hall Effect• Accommodates TeachSpin silicon and copper samples• Permanent-magnet structure provides reversible B-field• Transparent connections for tracking polarity• Unambiguously gives sign of charge carriers, for n- and p-type Si and for Cu• Permits 4-wire measurement of resistivity in semiconductors• Comes with current-limiting resistor and current-reversing switch• Guides students to first-principles measurements of sign and magnitude of B-field

FOUNDATIONAL MAGNETIC SUSCEPTIBILITY

ROOM TEMPERATURE HALL EFFECT

DEMYSTIFY & QUANTIFY DIA- & PARA-MAGNETISM

DEMONSTRATE & MEASURE THE HALL EFFECT

TWO-SLIT INTERFERENCE, ONE PHOTON AT A TIMEu Recreate Young’s two-slit measurement of the wave- length of lightu Perform two-slit interference with single-photon source and detectoru Investigate quantitatively the one-slit and two-slit interference patternsu Learn the properties of photomultiplier tubes and pulse discriminatoru Use Counter’s computer interface to investigate the statistical properties of photon events

OPTICAL PUMPING of RUBIDIUM VAPOR

u Optical pumping of rubidium atoms, Rb85 and Rb87

u Explore magnetic hyperfine interactions of rubidiumu Observe zero-field transitionsu Confirm Breit-Rabi equation

u Observe double quantum transitionsu Study Rabi Oscillationsu Measure optical pumping timesu Study temperature dependence of experimental parameters

DIODE LASER SPECTROSCOPY u Perform Doppler-free spectroscopy of rubidium vaporu Use Michelson and Fabry-Perot interferometers for calibrationu Observe resonant Faraday rotation in Rb vaporu Observe Coherent Population Trappingu Measure temperature dependence of absorption and dispersion coefficients of Rb vaporu Lock laser to rubidium hyperfine transitionu Study Zeeman splitting in Rb spectrum at two wavelengthsu Study stabilized diode laser characteristics

EARTH’S FIELD NMR withGRADIENT/FIELD COILS

u Observe the free-induction-decay signals from protons, fluorine, and other nucleiu Discover Curie’s Law and spin-lattice relaxationu Cancel out local gradients to obtain long-lasting precession signalsu Use Helmholtz coils for absolute measurement of proton magnetic momentu Create a one-dimensional magnetic resonance image (MRI)u Generate (and hear!) audio-frequency ‘spin echoes’u Includes spin-flip coils for investigations of resonant excitation

TORSIONAL OSCILLATOR

u Experiments in Simple Harmonic Motion appropriate at all undergraduate levelsu Independently adjustable torsion constant, rotational inertia, and dampingu Precision analog angular-position and angular-velocity transducersu Magnetic torque actuator permits arbitrary drive waveformsu Eddy-current (v1), sliding-friction (v0), and fluid-friction (v2) damping options

SIGNAL PROCESSOR/LOCK-IN AMPLIFIER

u A teaching lock-in amplifieru Multiple electronic strategies for processing electronic signalsu Built-in noise generator and test signalsu Follow the signal path u Modular design

MODERN INTERFEROMETRY

u Build Michelson, Sagnac, and Mach-Zehnder interferometersu Generate and count interference fringes manually or electronicallyu Use ‘quadrature Michelson’ interferometry to count bi-directionallyu Perform experiments in thermal expansion, magnetostriction, index of refraction, and the electro-optic and piezoelectric effectsu Observe white-light interference and quantify optical coherenceu Measure thickness interferometrically with 80-nm resolutionu Includes two lasers, proprietary mirror mounts, up-down electronic counter, multiple detectors, etc. – everything you need for a course in interferometric measurements

MAGNETIC TORQUE

u Measure magnetic moment, µ, FIVE independent waysu Observe classical analog of magnetic resonanceu Model nuclear precession and NMR spin-flip

FARADAY ROTATION u Measure Verdet constant of transpar- ent solids and liquidsu Study interaction of light, matter, and magnetic fieldsu Use with Lock-in Amplifier to measure extremely small Verdet constants

QUANTUM ANALOGS

Acoustic models of:u Hydrogen atom and hydrogen moleculeu Lowering symmetry to lift degeneracyu Band gaps in semiconductorsu Impurity states in semiconductors

Thermodynamic measurement of:u Velocity of sound in air and other gasesu Velocity of sound as a function of temperature

MAGNETIC FORCE

u Discover magnetic force depends on field gradientu Measure µ from magnetic force

MUON PHYSICS

u Detect cosmic-ray Muon fluxu Measure lifetime of stopped Muonsu Demonstrate relativistic time dilation

HALL EFFECT PROBE

u Measure the magnetic fields you teachu High sensitivity 2 x 10-6 Tu Student calibration of probe

POWER/AUDIO AMPLIFIER

u True bipolar amplifieru DC – 20 kHz, 10 V p-p, 1 A outputu Low impedance output

COUNTER/TIMER

u True events per-unit-time counteru Measure interval time with μs resolutionu Built-in pulse-height discriminatoru USB interface for computer logging

ULTRASONIC EXPERIMENTS(Collaboration with GAMPT/Germany)

SET 4 ADVANCED APPLICATION OF PULSED ULTRASONICSTeachSpin is the designated distributor in the US of the complete line of GAMPT Ultrasonic instruments. We carry all the GAMPT apparatus including Doppler measurements, medical applications, acousto-optic effects, and computer tomography. Any of GAMPT’s standard ‘sets’ or custom made ‘sets’ can be obtained through TeachSpin. Our proprietary manual is only available through TeachSpin.

DEBYE-SEARS EFFECT, The Basis of Acousto-Optic Modulationu Investigate velocity of propagation, frequency dependence, wavelength, acoustic impedance and absorption coefficients in both liquids and solidsu Observe and characterize both compression and shear waves in solidsu Learn non-destructive detection of imperfections, cracks, vacancies, and defects in solidsu Study the effects of both impedance matching and mismatching at material interfacesu Create an ultrasonic diffraction ‘grating’ using the CW generator and the broadband ultrasonic transducer (Debye-Sears effect)u The proprietary TeachSpin instruction manual emphasizes the basic physics of ultrasound measurements, gives references to the literature, provides self-discovery student experiments, encourages data collection on digital oscilloscopes, and offers self-directed student projectsu Learn experimental skills transferable to other pulsed time-domain investigations

About TeachSpinStarted in a basement to build a table-top Pulsed NMR designed specifically for teaching, TeachSpin now offers a wide range of instruments to an increasingly international constituency. We keep on growing into our mission – to build rugged, reliable, and affordable, hands-on instruments that make it possible for any institution, regardless of its size or the particular specialties of its faculty, to teach a wide variety of modern and classic advanced laboratory experiments. And, while teaching important concepts and experimental skills, TeachSpin instruments provide a ‘wide intellectual phase space’, with choices of parameters and open-ended investigations that give students real ownership.

Many TeachSpin instruments were developed in collaboration with faculty who have created unique experiments for their own students and worked with us to make them available to the entire physics community. Now, partnering in another venue, we have created teaching materials and hardware that use electronics developed by other companies. UltraSonics uses GAMPT signal generators and transducers to explore the physics of a field important in both research and medicine. Fourier Methods, designed around the Stanford Research Systems updated SR770, introduces students to the incredible power of Fourier thinking, providing insights that may well enhance their contribution to whatever field of experimental or theoretical physics they pursue.

All of us here at TeachSpin share a passionate commitment to advanced laboratory education and to the faculty and staff who are making sure that this generation of students will have the tools to make tomorrow’s new discoveries.

Barbara and Jonathan

Instruments DesIgneD for teachIng

2495 Main Street, Suite 409 uTri-Main CenterBuffalo, New York 14214-2153

Phone: (716) 885-4701 uFax: (716) 836-1077www.teachspin.com

Training at TeachSpinA full day of personal attention from the physicists who design and build our apparatus will prepare you to teach a new instrument with confidence or offer an opportunity to explore more advanced applications of an old favorite.

Come alone or with a colleague. In addition to enhancing your instructional and technical expertise, you will get a chance to see the TeachSpin factory in action. You might even find yourself chiming in, over lunch, as we brainstorm development ideas for our next great experiment.

Individual parts, such as proprietary photodetectors and the optical pumping light source, are available upon request.