## Physics Clinic

The Harvey Mudd College Clinic Program is a nationally recognized industry sponsored academic program centered around a multidisciplinary approach to real world problem solving. The program consists of roughly 40 projects per year sponsored by industry, in the departments of engineering, computer science, mathematics, and physics. Since the inception of the Clinic Program over 40 years ago, approximately 1000 projects have been sponsored by more than 250 individual sponsors.

The Clinic Program presents opportunities for juniors and seniors to work on practical projects relevant to industry. The problems usually involve components of measurement, design, simulation, and analysis. Solutions arise from team efforts which integrate the broad laboratory and discipline-specific skills that characterize a Harvey Mudd College education. Students who are enrolled in the Clinic Program work in teams of four or five under the guidance of a student team leader, a faculty advisor, and a liaison from the sponsoring organization. Some projects are jointly run by two or more departments to promote cross-fertilization between fields, and to encourage application of diverse viewpoints and a variety of techniques. In addition to putting into practice the theories learned in the classroom, students must deal with the psychology of teamwork, as well as budget and schedule constraints.

 2014 — Integrated Dynamic Electron Solutions Dynamic Transmission Electron Microscopy 2013 — Aerosol Dynamics, Inc. A Portable, Tippable Airborne Particle Counter 2013 — Trivec Avant Corporation, a COBHAM Company Developing a Compact, Planar, Ultra-Wideband Antenna 2013 — Sandia National Laboratories Measuring Nanoparticle Permittivity in Colloidal Suspension 2013 — Lawrence Livermore National Laboratory A Tunable Resonant Microwave Cavity for the Axion Dark Matter eXperiment 2012 — Lawrence Livermore National Laboratory Design of a Hybrid Antineutrino Detector Using Scintillation and Wavelength-Shifting Materials 2012 — SLAC National Accelerator Laboratory Femtosecond Laser Timing Measurement 2012 — Artemis Innovation Management Solutions, LLC Microwave Power Transmitter-Receiver for Application to Space Power 2011 — Lawrence Livermore National Laboratory Axion Dark Matter Experiment 2010 — Lawrence Livermore National Laboratory Liquid Organic Scintillator Detectors for Nuclear Material Monitoring 2010 — Southwest Research Institute Data Inversion For a New Spectral Imaging Technique 2009 — Cardinal Health Modeling Fluid Transport in Subcutaneous Tissue 2009 — Lawrence Livermore National Laboratory Calibration Source for a Prototype Car-Wash Detector of Fissile Material 2008 — Southwest Research Institute Modeling the Performance of a Jupiter Electron Sensor in Strong Magnetic Fields 2008 — HMC Physical Plant & Campus Planning Committee of the Board of Trustees – Sustainability Clinic Guiding Sustainability at Harvey Mudd College 2007 — Lawrence Livermore National Laboratory Muon Veto System for a Reactor-Monitoring Anti-neutrino Detector 2007 — Los Alamos National Laboratory Design and Construction of a Thermal Link for Optical Isolation 2005 — Lawrence Livermore National Laboratory Implementation of Adaptive Optics in a Clinical Ophthalmic-Imaging Instrument 2005 — Sandia National Laboratory Measuring the Optical Properties of Coated Soot Particles 2005 — Sandia National Laboratories Optical Characterization of Coated Soot Aerosols or "Flames and Laser" 2004 — Sandia National Laboratories Measuring the Optical Properties of Coated Soot Particles 2004 — University of California Irvine Department or Otolaryngology Modification of Laryngoscope for Optical Coherence Tomography 2003 — Northrop Grumman A MEMS Vibrating Beam Gyroscope 2003 — Northrop Grumman Electronic Systems Vibrating Beam Angular Rate Sensors 2002 — Jet Propulsion Laboratory The Challenge of Pointing Stability and Accuracy in the Space Interferometer Mission (SIM) 2001 — Etec Systems, Inc., An Applied Materials Company A Method for Beating the Diffraction Limit in Photolithography 2001 — Jet Propulsion Laboratory LA-ARB-1: A Magnetotactic Bacterium 2001 — Trivec Avant Compact Planar, Omnidirectional, Ultra-wideband Antenna 1999 — Jet Propulsion Laboratory Infrared Interferometer 1999 — Optivus Technology, Inc. Design of a Detector Electronics System for Feedback Control of Proton Beam Intensity in the LLUMC Proton Medical Accelerator 1998 — Aerojet Innovation for the Next Generation 1997 — Arete Associates Software Simulation of Water Surface Optical Glitter 1996 — Aerojet/Gencorp Field-Widened Fourier Transform Spectrometer 1996 — BHK, Inc. Designing and Modeling a High Intensity Deuterium Lamp 1996 — Science Applications International Corporation (SAIC) Even Illumination Light Source

#### Dynamic Transmission Electron Microscopy

Integrated Dynamic Electron Solutions
Year
2014 – 2015
Peter N Saeta
Team
Natasha (Tasha) Arvanitis (’15)
Allison Mis (’15)

#### A Portable, Tippable Airborne Particle Counter

Aerosol Dynamics, Inc.
Year
2013 – 2014
Thomas D Donnelly

Aerosol Dynamics has patented a novel process called diffusive mixing that could be used to grow water droplets around airborne nanoscale particles and improve the efficiency of aerosol counters.  The Clinic team’s project is to develop computational models to simulate diffusive mixing, and then design and build a prototype aerosol counter which implements the diffusive mixing technique.

#### Developing a Compact, Planar, Ultra-Wideband Antenna

Trivec Avant Corporation, a COBHAM Company
Year
2013 – 2014
John Molinder

Most antennas with wideband range and high directionality are three dimensional in shape, with spiral and bicone antenna geometries as notably useful and common examples.  A three-dimensional shape makes antennas non-ideal for aerospace applications.  Trivec Avant asked the Clinic team to develop a planar, ultra-wideband antenna (225 MHz–2000 MHz) with return loss below –5 dB and directivity at azimuth above –6 dBi across the entire frequency band.

#### Measuring Nanoparticle Permittivity in Colloidal Suspension

Sandia National Laboratories
Year
2013 – 2014

The Sandia National Laboratories clinic team characterized the permittivity of barium titanate particles in colloidal suspension as a function of primary particle size, synthesis method, and surfactant choice using electrochemical impedance spectroscopy.  To accomplish this goal, the team has built a sample holder to contain the suspension, developed a procedure to extract nanoparticle permittivity from the suspension permittivity, and integrated both of these deliverables into a testing procedure.

#### A Tunable Resonant Microwave Cavity for the Axion Dark Matter eXperiment

Lawrence Livermore National Laboratory
Year
2013 – 2014

The LLNL Clinic Team has simulated, designed, built, and tested a large-volume, high-frequency resonant microwave cavity to be used in the Axion Dark Matter experiment (ADMX).  Multiple conductive tuning posts within the cavity are used to manipulate the characteristic modes of the system, allowing the cavity to potentially detect axions, a possible candidate for dark matter, by tuning the cavity resonant frequency.

#### Design of a Hybrid Antineutrino Detector Using Scintillation and Wavelength-Shifting Materials

Lawrence Livermore National Laboratory
Year
2012 – 2013

Sensitive monitoring of antineutrino flux from nuclear power plants documents the consumption of fissile materials, thereby enhancing nuclear safeguards and non-proliferation.  In the team’s newly designed hybrid scintillation detector, energy depositions from prompt gamma rays and delayed neutron capture events provide an unambiguous signal for antineutrino detection.  Dual scintillation materials are used with wavelength-shifting plastics to direct light to photomultiplier tubes most efficiently.  Material characterization tests and Monte Carlo simulations were used to optimize the design of the detector.

#### Femtosecond Laser Timing Measurement

SLAC National Accelerator Laboratory
Year
2012 – 2013

The SLAC clinic team is working with researchers from the LINAC Coherent Light Source, the world’s brightest X-ray laser.  Our goal is to reduce timing errors that occur when synchronizing laser pulses in their pump-probe experiments.  Since researchers believe the current 250 femtosecond ($$2.5 \times 10^{-13}~\text{ s}$$) timing error is primarily caused by their photodiodes, the team built a timing platform to characterize the errors introduced by these devices.

#### Microwave Power Transmitter-Receiver for Application to Space Power

Artemis Innovation Management Solutions, LLC
Year
2012 – 2013
Qimin Yang

The Harvey Mudd College Artemis clinic team will design, build, and test a mobile prototype of a microwave transmitter and receiver system for wireless solar-generated power transmission operating at 2.45 GHz.  The clinic team will construct a prototype capable of transmitting 100 watts of power at a distance of 100 meters.  The prototype will be modular in design and possess beam directional control capability.

#### Axion Dark Matter Experiment

Lawrence Livermore National Laboratory
Year
2011 – 2012

The Axion Dark Matter Experiment (ADMX) clinic project is sponsored by Lawrence Livermore National Laboratory to develop a piezo-electric rotary drive system.  This drive system will move tuning rods within a microwave cavity to adjust the cavity’s resonant frequency as it scans for signatures of axion dark matter.  The system must be able to operate with heat generation on the order of 100 microwatts or less at 0.1 K in an 8 T magnetic field and 10-6 torr vacuum.

#### Liquid Organic Scintillator Detectors for Nuclear Material Monitoring

Lawrence Livermore National Laboratory
Year
2010 – 2011

The joint Physics/Engineering project sponsored by LLNL aims to research a potential organic scintillator for use in an antineutrino detector.  Such a detector must have neutron-gamma discrimination capabilities, and the HMC team will test those capabilities for various cell dimensions and reflectivity levels.  The team will also investigate the relative efficacy of two different algorithms for discriminating between neutron and gamma events.   The result of the team’s research will inform the direction of LLNL’s next antineutrino detector.

#### Data Inversion For a New Spectral Imaging Technique

Southwest Research Institute
Year
2010 – 2011

The SHAZAM system is able to take very high resolution data of the Sun’s magnetic field through a new technique called Stereoscopic Spectroscopy.  This technique combines a unique instrument setup with new reduction algorithms to allow for full integration over all wavelengths and spatial dimensions.  This Clinic project produced a data processing pipeline that performs standard data reduction, cross correlation stereoscopy, and newly developed differential stereoscopy on recorded data in order to produce final magnetograms.

#### Modeling Fluid Transport in Subcutaneous Tissue

Cardinal Health
Year
2009 – 2010

The goal of this project is to produce a mathematical model of fluid flow in subcutaneous tissue.  Two models have been developed: a compartment model that segregates the fluid into homogeneous regions, and a continuous model that describes the properties of the fluid at each point in space and time.

#### Calibration Source for a Prototype Car-Wash Detector of Fissile Material

Lawrence Livermore National Laboratory
Year
2009 – 2010

The joint Physics-Engineering clinic team has designed and constructed a waterproof, tagged neutron source for the purpose of calibrating a new type of neutron detector currently in development at LLNL.  The calibration of the LLNL detector is required to verify that its efficiency is maintained as the detector is scaled up to the size required for security scanning at major ports of entry as part of a program aimed at non-proliferation of fissile material.

#### Modeling the Performance of a Jupiter Electron Sensor in Strong Magnetic Fields

Southwest Research Institute
Year
2008 – 2009
Vatche Sahakian

In August of 2011, NASA will launch the satellite Juno to conduct an in-depth study of the planet Jupiter. On board the satellite there are three electrostatic analyzers (ESAs) that will measure the energy and trajectory direction of electrons in Jupiter’s auroras. The behavior and performance of ESAs is well understood in the absence of a magnetic field. It was the task of this Clinic team to account for the effect of these magnetic fields. The team ran computer simulations of the ESAs in magnetic fields of varying magnitude and direction. Mathematical models were then devised for the energy of the electrons and their incoming angle relative to the direction of the magnetic field. These models can be used to translate the data that will be collected by the ESAs into a map of the spectrum of the electrons near Jupiter.

#### Guiding Sustainability at Harvey Mudd College

HMC Physical Plant & Campus Planning Committee of the Board of Trustees – Sustainability Clinic
Year
2008 – 2009
Daniel C Petersen

The team was asked to systematically evaluate a broad range of possible conservation-themed projects to improve campus sustainability at HMC.  The team developed a set of metrics that prioritizes and compares the performance of diverse projects such as real-time monitoring of electricity usage, solar photovoltaics, and improvements to landscaping.  The metrics will also be used to evaluate future HMC sustainability projects.

#### Muon Veto System for a Reactor-Monitoring Anti-neutrino Detector

Lawrence Livermore National Laboratory
Year
2007 – 2008

The Clinic team designed, constructed, and tested a new muon veto system for LLNL’s second generation cubic meter scale antineutrino detector for use in reactor monitoring applications.  To maximize the efficiency and effectiveness of this veto system the team conducted tests to characterize the spatial response of different types of muon veto paddles.

The team also conducted simulations to verify and extend our experimental data.  The team designed and implemented a framing system to hold the muon veto paddles in a robust and gap-free arrangement around the anti-neutrino detector.

#### Design and Construction of a Thermal Link for Optical Isolation

Los Alamos National Laboratory
Year
2007 – 2008

The Los Alamos National Laboratory Solid State Optical Refrigerator cools a Ytterbium doped fluoride glass with a high power infrared laser, and presents the means for vibrationless localized cooling to 77 K. For practical cooling implementation, photon absorption on an attached thermal load must be greatly reduced. The team has designed, constructed, and tested a thermal link to attach to the system that optically isolates the thermal load and that minimizes photon absorption within the link.

#### Implementation of Adaptive Optics in a Clinical Ophthalmic-Imaging Instrument

Lawrence Livermore National Laboratory
Year
2005 – 2006
Among the central themes of vision research within the United States today, are the efforts to understand the limits of human visual acuity and the changes in vision associated with aging and retinal disease. The Adaptive Optics group at Lawrence Livermore National Laboratory (LLNL), in collaboration with researchers at the UC Davis Medical Center (UCDMC) and the University of Rochester, has applied adaptive optics technology to the study of the human eye to: (1) measure the visual performance of the eye when virtually all the aberrations of the eye are corrected, and (2) obtain high-resolution images of the retina, thereby allowing correlation of retinal structure with visual performance. The research program at UCDMC has focused specifically on the optical and neural factors responsible for the normal aging of the human visual system, and cellular mechanisms of age-related macular degeneration (AMD), the leading cause of blindness in the United States. The goal of the LLNL clinic project at Harvey Mudd College is to convert the current adaptive optics ophthalmic-imaging instruments from prototype/bench-top systems into a “clinical” instrument. The Harvey Mudd team will be responsible for the development of a next-generation ophthalmic imaging instrument that incorporates new design features aimed at improving the clinical utility of the instrument, for instance, by reducing its size and by making it easier to be operated by a trained technician. The HMC team will implement a broad range of optical, mechanical and software improvements required to make these changes.

#### Measuring the Optical Properties of Coated Soot Particles

Sandia National Laboratory
Year
2005 – 2006
Soot particles are a common byproduct of combustion. These sub-100-nm carbon particles can lodge deep in the lungs, leading to cardiovascular and pulmonary health problems. They also contribute significantly to air pollution and potentially to global warming. Recent work has clarified the absorption and scattering properties of bare carbon particles in sunlight, but impurities in fuel often produce carbon particles coated with significant layers of sulfur and other dielectric compounds. To understand the role carbon aerosols play on global climate, and potentially to build remote optical diagnostics of soot emissions, it is necessary to measure the optical properties of these coated nanoparticles. The goal of this clinic is to characterize the light absorption and scattering properties of coated soot aerosols. Soot particles will be generated in the lab by partially combusting ethylene and subsequently coated via a particle coating condenser. Their optical properties will be determined using angle-resolved scattering and cavity ringdown techniques. Last year's team built most of the apparatus, including the means to filter the soot from the exhaust air so it can be exhausted into the room. This year's team is refining the setup, calibrating both ringdown and angle-resolved scattering setups, and investigating the impact of oleic-acid coatings.

#### Optical Characterization of Coated Soot Aerosols or "Flames and Laser"

Sandia National Laboratories
Year
2005 – 2006

The optical properties of coated soot aerosols produce the greatest uncertainty in climate change models.  This project aims to measure the scattering and absorption of light by sub-micron-sized soot particles similar to those produced in diesel exhaust.  Total absorption and scattering cross sections of 635 nm laser light are measured using cavity-ringdown and angle-resolved scattering techniques.  Soot particles are created in situ by partially combusting ethylene and coated with a volatile organic compound.

#### Measuring the Optical Properties of Coated Soot Particles

Sandia National Laboratories
Year
2004 – 2005
Robert P Wolf
Soot particles are a common byproduct of combustion. These sub-100-nm carbon particles can lodge deep in the lungs, leading to cardiovascular and pulmonary health problems. They also contribute significantly to air pollution and potentially to global warming. Recent work has clarified the absorption and scattering properties of bare carbon particles in sunlight, but impurities in fuel often produce carbon particles coated with significant layers of sulfur and other dielectric compounds. To understand the role carbon aerosols play on global climate, and potentially to build remote optical diagnostics of soot emissions, it is necessary to measure the optical properties of these coated nanoparticles. The goal of this clinic is to characterize the light absorption and scattering properties of coated soot aerosols. Soot particles will be generated in the lab by partially combusting ethylene and subsequently coated via a particle coating condenser. Their optical properties will be determined using angle-resolved scattering and cavity ringdown techniques.

#### Modification of Laryngoscope for Optical Coherence Tomography

University of California Irvine Department or Otolaryngology
Year
2004 – 2005

Currently laryngeal cancer can only be diagnosed with biopsies which are invasive, permanently damaging, and can miss cancerous tissue.  Optical Coherence Tomography (OCT) is an imaging technique that non-invasively images several millimeters into tissue to seek structural abnormalities, which can indicate cancer.  We will design and construct an OCT device for attachments to a laryngoscope that will image two-dimensional cross-sections in the larynx, for the purpose of diagnosing laryngeal cancer in its early stages.

#### A MEMS Vibrating Beam Gyroscope

Northrop Grumman
Year
2003 – 2004
Peter N Saeta
This year’s project continues the work of last year’s on vibrating beam angular rate sensors, but aiming to develop an over-size working prototype compatible with MEMS production techniques.

#### Vibrating Beam Angular Rate Sensors

Northrop Grumman Electronic Systems
Year
2003 – 2004
Peter N Saeta
Robert P Wolf

Northrop Grumman is the second largest defense contractor in America, designing and producing a wide variety of technologies ranging from aircraft to sensors.  The clinic team performed a proof-of-concept study using microelectrical mechanical systems (MEMS) technology to produce a vibrating beam angular rate sensor based on the Coriolis force.  Experimental and analytical results were reported.

#### The Challenge of Pointing Stability and Accuracy in the Space Interferometer Mission (SIM)

Jet Propulsion Laboratory
Year
2002 – 2003

SIM is an orbiting interferometer telescope capable of relative star measurements 100 times more accurate than ever before.  Specifically, the team is devising a technique for measuring the spacing between telescopes, measuring changes in distance to an accuracy of 100 picometers, or 1 angstrom, roughly the size of a hydrogen atom.

#### A Method for Beating the Diffraction Limit in Photolithography

Etec Systems, Inc., An Applied Materials Company
Year
2001 – 2002
Peter N Saeta

Etec Systems, Inc. is a worldwide leader in the designing, manufacturing, and marketing of mask-making solutions for the semiconductor industry.  Our Clinic team is providing Etec with a feasibility study on a potential technology for tightening the focus point of a laser on the photoresist layer of a mask beyond the normal diffraction limit, enabling the writing of smaller mask features.  We report both analytical and experimental results.

#### LA-ARB-1: A Magnetotactic Bacterium

Jet Propulsion Laboratory
Year
2001 – 2002
Nancy Hamlett
Alexander Rudolph

The Jet Propulsion Laboratory Clinic team investigated various behavior aspects of a novel magnetotactic bacterium, LA-ARB-1.  Aerotaxis, phototaxis, motility, and viability studies were the focus of the team’s investigations.  Results from their work contribute to a better understanding of how LA-ARB-1 uses its internal structure to take advantage of its unique environment.

#### Compact Planar, Omnidirectional, Ultra-wideband Antenna

Trivec Avant
Year
2001 – 2002
John Molinder

While modern software radio systems are compact and capable of output across a wide frequency range, existing antenna designs capable of transmitting across a wide frequency range in all directions are too wide and unwieldy for many mobile platforms.  Trivec Avant Corporation team has tasked the Harvey Mudd team with designing a compact, planar, and ultra-wideband (225-20000MHz) antenna that radiates omnidirectionally in azimuth.

#### Infrared Interferometer

Jet Propulsion Laboratory
Year
1999 – 2000
Alexander Rudolph

The Jet Propulsion Laboratory Clinic team constructed a modified Michelson interferometer to combine the light from two 10-meter Keck telescopes situated on the island of Hawaii. The system combines two 1" infrared beams of light from the telescopes and incorporates feedback control to ensure that the optics are correctly focusing the collimated beams into fiberoptic cables. The telescope system will allow for the direct detection of Hot Jupiter planets in other solar systems.

#### Design of a Detector Electronics System for Feedback Control of Proton Beam Intensity in the LLUMC Proton Medical Accelerator

Optivus Technology, Inc.
Year
1999 – 2000
Samuel (Sam) Tanenbaum

Optivus Technology uses a proton accelerator as a radiation source for treating cancer patients. The current method of attacking tumors with the proton beam has been successful, but Optivus would like to improve the treatment by using a raster-scanning technique, requiring a much tighter control on the beam intensity. Our goal is to develop an improved electronics system to process the output of a beam intensity detector, allowing a feedback loop to control the beam at a much higher bandwidth.

#### Innovation for the Next Generation

Aerojet
Year
1998 – 1999
Aerojet's current Advanced Microwave Sounding Unit (AMSU) orbits the earth, passively measuring the intensity of particular microwave frequencies for meteorological purposes. The team has explored and analyzed a number of new and innovative technologies in an effort to reduce the size and manufacturing cost of the AMSU receiver subsystem. Extensive research was done to determine the fundamental properties of the different technologies in order to pinpoint their limitations and foresee possible advances. The team has proposed feasible alternatives to the design of the current AMSU.

#### Software Simulation of Water Surface Optical Glitter

Arete Associates
Year
1997 – 1998
Gregory (Greg) A. Lyzenga
The clinic team investigated and developed models for the reflection of the sun off the ocean's surface to create an improved “glitter” routine for Arete Associates' RenderWorld, their software package for modeling natural scenes. Current software techniques do not allow for efficient simulations of light reflection off small-scale water waves (referred to as glitter) because it is too computationally intensive. The team developed a software implementation of its recommended solution to Arete Associates. Images generated using the RenderWorld's package will be shown.

#### Field-Widened Fourier Transform Spectrometer

Aerojet/Gencorp
Year
1996 – 1997
James (Jim) Monson
Robert P Wolf

The Fourier Transform Spectrometer (FTS) is a widely-used instrument for spectral analysis of thermal sources. The interferometry based FTS has a limited field-of-view (FOV). Gencorp/Aerojet has contracted the Harvey Mudd College Engineering/Physics Clinic team to determine the feasibility of a field-widened FTS. Extensive research has been carried out towards the understanding of both internal and external FOV constraints of the FTS. The focus on internal constraints has led to several interferometry design approaches; the most promising design utilizes a mechanically deformable cat?s eye mirror, which in place of the traditional plane moving mirror, allows for change in the curvature of the mirror as the cat’s eye is moved. Alternate designs include lens focusing systems and the addition of dispersive media. The team explored these prospective designs for a field-widened system through feasibility studies and performance evaluations.

#### Designing and Modeling a High Intensity Deuterium Lamp

BHK, Inc.
Year
1996 – 1997
Graydon Bell
Robert P Wolf

BHK requested a design for a deuterium lamp that has a higher output and greater lifetime than existing lamps on the market. The team developed a model relating to such parameter as fill composition, pressure, and geometrical measurements to the intensity and spectral characteristics of the output, and suggested and evaluated design modifications to improve performance.