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For more information, contact:

Prof. Robert H. GilesDepartment ChairPhone: 978-934-3779Email: Robert_Giles@uml.edu

Prof. Partha ChowdhuryGraduate Program CoordinatorPhone: 978-934-3730Email: Partha_Chowdhury@uml.edu

Lecturer Nikolay LepeshkinUndergraduate Program CoordinatorPhone: 978-934-3193Email: Nikolay_Lepeshkin@uml.edu

Department of Physics and Applied PhysicsOlney Science Center 136CUniversity of Massachusetts LowellOne University Avenue, Lowell, MA 01854

Merging Science with TechnologyThe Physics and Applied Physics Programs at the University of Massachusetts Lowell

uml.edu/physics

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From the Chair

The Department of Physics and Applied Physics at the University of Massachusetts Lowell continues

to build new academic programs through the dedication of its faculty to teaching, research and

service. Leading investigations in the areas of materials science, device-fabrication techniques and

source/detector technologies, our faculty are pioneering cutting edge-research in nuclear physics,

advanced materials, photonic devices, terahertz technologies, biomedical photonics and atmos-

pheric and space physics. Based on the strategic growth and academic diversity of our faculty,

the department continues to posture for greater achievements in each of these areas.

Leveraging the recently articulated vision for the entire university for the upcoming years—

called the “UMass Lowell 2020 Five Pillars of Excellence”—our department is a destination for

the next generation of scholars and students.

Recognized for their innovative research, global engagement and methods of transformational

education, the faculty members of physics lead the implementation of the university’s goal of

becoming a world-class research university.

With excellent graduate and undergraduate programs supported by exemplary research and

scholarships, the Physics Department has partnered with local, national and international institu-

tions in broadening its framework of academic research. The result is a major doctoral-level

research department, ranging from substantial increases in externally funded research to exciting

new educational opportunities for undergraduate and graduate students alike.

The synergistic goals of academic research and education have enriched our population of alumni

in prominent academic institutions, government research laboratories and industrial facilities

across the nation and abroad.

Students who wish to learn more about the exciting B.S., M.S. and Ph.D. programs in physics

offered at UMass Lowell should review our website, www.uml.edu/physics, or contact me

directly at the university. I look forward to hearing from you.

Robert H. Giles, Ph.D.

Chair

Department of Physics and Applied PhysicsOlney Science Center 136CUniversity of Massachusetts LowellOne University AvenueLowell, MA 01854

Merging Science with TechnologyThe Physics and Applied Physics Programs at the University of Massachusetts Lowell

2 Meet Our New Faculty MembersTheorists Conduct Research on Cosmology, Stellar Atmospheres, Quantum Engineering, Soft Matter

4 Radiation LaboratoryInterdisciplinary Program in Nuclear Science and Technology

7 Radiological Health PhysicsA Growing Need for Radiological Sciences and Protection

8 Nanoscale Medical PhysicsFrom Low-cost Nanofilm Detectors to High-Z Nanoparticle Radiotherapies

10 Advanced Biophotonics LaboratoryBiomedical Optics and its Applications

11 Center for Advanced Materials’Green’ Chemistry and Engineering at UMass Lowell

12 Photonics CenterLaboratory for Advanced Semiconductor Epitaxy

14 Laboratory for Nanoscience and Laser ApplicationsCreating Nanostructures on Solid Surfaces Using Femtosecond Pulsed Laser

15 Multiscale Electromagnetics LaboratoryStudying Metamaterials and their Interactions with Light

16 Submillimeter-Wave Technology LaboratoryResearch Center Offers Breakthroughs in Terahertz Imaging

18 Biomedical Terahertz Technology CenterDeveloping Innovative Imaging Technology for Cancer Diagnosis

19 Lowell Center for Space Science and TechnologyResearchers Use Sounding Rockets and Balloons to Explore the Cosmos

21 EXCEL: An Experimental Center for Environmental LidarApplications in Terrestrial Ecology, Oceanographic Bathymetry and Aerodynamics

22 Astronomy and Astrophysics GroupX-ray Binaries as Astrophysical Probes, Multi-wavelength Observations and Time-domain Astronomy

23 Space Science LaboratoryInvestigating Space Weather, the Magnetosphere and Ionosphere

24 Haiti Development Studies CenterMaking Positive Change in the Impoverished Caribbean Nation

25 Physics Faculty and Expertise

On the Cover:

Undergraduate physics student Cameron Oliver works on the terahertz optical systems used for biomedicalimaging at the Biomedical Terahertz Technology Center. Bottom inset photos, from left: the uranium core ofthe UMass Lowell Research Reactor, the Photonics Center’s molecular beam epitaxy system and the spiralgalaxy M101 in Ursa Major.

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The Physics and Applied Physics Programs at the University of Massachusetts Lowell

www.uml.edu/physics

Table of Contents

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Nishant Agarwal, Ph.D.

Asst. Prof. Nishant Agarwal’s interest is to answer fundamentalquestions in physics and cosmology using a combination of high-precision cosmological data, numerical simulations and theoretical techniques.

“My research focuses on using detailed measurements of the cosmic microwave background [CMB] sky and multiple tracers of large-scale structure [LSS] in the universe to study theuniverse’s evolution, starting from its earliest stages to the currentenergy landscape dominated by dark energy and dark matter,” says Agarwal.

Astronomers believe that the universe underwent a phase ofrapid exponential expansion, called inflation, for a fraction of asecond just after the Big Bang.

“My work is to develop techniques to study perturbations ofquantum fields on such a background and their imprints in cos-mological data. I have used CMB and LSS data extensively toprobe the physics of inflation,” says Agarwal. “I am also inter-ested in understanding whether the perturbations generated during inflation could carry information from the pre-inflationaryuniverse, which would in turn give us important insights intoquantum gravity.”

The current universe is undergoing an accelerated expansiononce again, the reason for which is undoubtedly one of the deep-est mysteries of contemporary physics. “Unless we are observingthe effects of a non-trivial form of energy, commonly called darkenergy, the acceleration suggests that Einstein’s general relativitymight not be the correct description of gravity on large scales,”notes Agarwal.

He says any such deviations from general relativity would havealso left imprints, for example, in the growth of structure, redshiftspace distortions and, possibly, the equation of state of dark

energy at different redshifts. “I am interested in understandingwhat modifications of gravity are theoretically allowed, how theyaffect the evolutionary history of the universe and how our pertur-bative modeling of LSS interferes with constraints on dark energy.”

Another major constituent of the universe today is dark matter—the invisible matter that holds galaxies together. “Various dark matter candidates are expected to interact with radiation in the universe and influence galaxy formation,” saysAgarwal. “My work involves developing models which, in con-junction with upcoming polarization experimental data, could be used to test the existence of certain pseudo-scalar particlesthat might form at least part of dark matter.”

Ofer Cohen, Ph.D.

Asst. Prof. Ofer Cohen’s research involves high-performance, parallel computer simulations of the atmosphere of the Sun and other stars, solar and stellar winds, the interplanetary environment and the interaction of the space environment with the upper atmospheres of planets and their magnetic fields(magnetospheres).

“My research is highly interdisciplinary and it involves spaceand solar physics, heliophysics, astrophysics, planetary science andexoplanets, where the fundamental common line is plasmaphysics, or the physics of ionized gas,” explains Cohen. “The science topics I study are the evolution of the Sun and the spaceenvironment of the solar system in time, the impact of this evolution on the Earth, solar physics, space weather and spacehazards forecast, the atmospheres and the space environment of exoplanets and the atmosphere of the early Earth.”

He adds: “I use NASA, National Science Foundation and localsupercomputers to perform the massive simulations I need for my research.”

Meet Our New Faculty MembersTheorists Conduct Research on Cosmology, Stellar Atmospheres, Quantum Engineering, Soft Matter

Archana Kamal, Ph.D.

Asst. Prof. Archana Kamal’s research interests span quantum information and quantum engineering.

“My goal is to build systems that harness quantum effects forpractical applications such as quantum computation, measurementand optimization,” says Kamal. “Precise control of quantum dynam-ics envisioned within such systems will provide a means to test thefundamentals of quantum physics itself. My research lies at the interface of theory and experiments and encompasses several aspects of high-fidelity quantum information processing in low-dimensional systems.”

According to Kamal, one of the primary challenges for scalablequantum information processing is to realize quantum effects atmacroscopic scales while preserving the delicate physics. “I haveworked closely on both theory and experiments, focusing on qubitdesign and control and the characterization/mitigation of decoher-ence in these systems,” she says. “I am also exploring how stronglight-matter coupling readily available with Josephson circuits can be exploited for nonlinear quantum photonics and quantum simulation.”

Another component of her research focuses on developing high-fidelity measurement protocol. “The challenge is to get awaywith the minimum possible perturbation, or back action, as permit-ted by quantum mechanics. I am developing new schemes for quantum-limited amplification and detection; many of these arenow routinely employed in experiments in solid-state quantum computing,” says Kamal.

A related theme of her research is engineering symmetry breaking-in photon transmission and amplification. Photons are theuniversal carriers of information across several quantum informationplatforms. Since the laws of electromagnetism are inherently time-reversal invariant, photon-propagation and information transfer isnaturally reciprocal.

“My collaborators and I have developed schemes that implementseveral forms of nonreciprocal photon scattering,” says Kamal. “Unlike commercial nonreciprocal devices, our proposals do not relyon magnetic fields or introduce any dissipation, which are both extremely crucial considerations for any practical on-chip quantum-mechanical processor. Such dissipationless nonreciprocity, especiallyat the level of a few quanta, can be exploited to engineer novel cou-pling mechanisms between quantum systems. This opens doors to aqualitatively new paradigm for studying physics of strongly interacting quantum systems.”

Johannes Zwanikken, Ph.D.

Asst. Prof. Johannes Zwanikken performs theoretical research in“soft matter,” a highly interdisciplinary field at the interface ofphysics, mathematics, chemistry, biology, computer science and engineering.

“It involves the study of thesolid and liquid states of matter, and beyond that, a vastcollection of states of colloids,nanoparticles, biological matter,granular matter, active matter,vesicles, polymers and morecomplex manifestations of matter,” he says.

According to Zwanikken, theunderlying physics concerns itselfwith the connections betweenthe interactions at the molecularlevel and the emergence ofstructure and symmetry at larger length scales that give rise to mechanical, electric or optical properties. “These systems provideconcrete inspiration for fundamental questions in physics,” he says.

Zwanikken says although it is well known how the thermo-dynamic properties of a simple liquid are connected to the ratherchaotic motion of the molecules it consists of, much less is knownabout the behavior of “active matter,” systems that consist of driven particles such as bacterial colonies, self-propelled colloids and other non-ergodic systems.

“The collective behavior of active particles shows remarkable resemblance with thermodynamic systems, but also striking differ-ences,” he notes. “While active particles have the ability to phase-separate, reminiscent of a gas-liquid coexistence, the fluctuations of these phases follow completely different scaling laws, as yet eluding theoretical description.”

He adds: “Understanding the underlying physical principles of active matter would enable new methods for materials design andfor accelerating industrial processes that are limited by thermalprocesses, such as diffusion.”

Zwanikken and his collaborators are developing thermodynamicmodels for polymers and polyelectrolytes for applications in energystorage. Since the early 1970s, lithium has been the most popularelement for batteries since it is the lightest of all metals and has thegreatest electrochemical potential. But lithium-based batteries arehighly flammable and, when they overheat, they can burst intoflames.

In 2014 the group married two traditional theories in materialsscience that can explain how an ion charge dictates the structure of plastic materials known as block copolymers. This opened thedoor for many applications, including a new class of safer, polymer-based batteries. Their work was featured on the front cover of “Nature Materials.”

Merging Science with Technology Fall 2016 uml.edu/physics

At the center of all atoms in the universe are the nuclei, whichprovide 99.99 percent of the atoms’ mass and form the core of allmatter. Learning how these tiny systems work teaches us abouthidden forces in nature that are found only inside the nuclei,forces that generate almost all the energy that powers the sunand stars and make life possible here on Earth. The atomic nucleiplay a crucial role in the history of our universe through the for-mation of heavy elements, and all the atoms that comprise us and the world we live on were forged by the stars. Thus, we are all stardust. A century after the discovery of the nucleus, new experiments, particle accelerators and detector technologiesare being developed to synthesize and study thousands of previously unknown isotopes and deepen the universality of our understanding.

UMass Lowell’s Radiation Laboratory offers a balanced portfo-lio of academic and applied research on this field. On the aca-demic side, we have programs that measure and calculate thelightest nuclei from first principles, study fission fragments and ex-plore the balance of forces that dictate what the heaviest nucleimight form and how to synthesize them. To fathom the quantummechanics of these systems has required many new experimentaland theoretical techniques to be developed, methods which have

devolved into all branches of science. Applied nuclear techniquesare now used in medical diagnostics and therapeutics, space sci-ence, power generation, stockpile stewardship, environmentalmonitoring, homeland security, geology and oceanography, aswell as many other new and emerging sciences.

The university has a long history of excellence in nuclear science. The Radiation Laboratory features a 1-megawatt (MW)research reactor and a 5.5-million-volt (MV) Van de Graaff acceler-ator, enabling both academic and applied research avenues. The facility is especially well-equipped for neutron science, withthermal neutrons produced with the reactor and fast neutronswith the accelerator. Partnerships with industry and national labo-ratories are in place for developing new detector technologies. For example, new scintillating detector materials from a local Massachusetts company show great promise for fast-neutronspectroscopy, while others have an extremely fast response forgamma rays. Another avenue of research is in the development of position-sensitive germanium detectors for medical imaging,space science and homeland security with a company from Oak Ridge, Tenn.

Another new direction in interdisciplinary research is the creation of a proton microprobe, funded by a Science and

Radiation LaboratoryInterdisciplinary Program in Nuclear Science and Technology

Technology grant from the UMass President’s Office,which will enable the focusing of the accelerator’s pro-ton beams down to micron sizes. Potential applicationsrange from surface modification and characterization inmaterials science to biomedical research, such as map-ping specific metal content in the brain that has beentied to Alzheimer's disease.

UMass Lowell students and post-doctoral researcherslead many of these projects, working with a robust in-house infrastructure for multi-parameter data acquisitionand analysis as well as digital signal processing. A newgrant from the National Nuclear Security Administrationis funding the R&D to develop an array of new scintilla-tors capable of detecting and differentiating betweenthermal neutrons, fast neutrons and gamma raysthrough differences in their pulse shapes. Students alsorepair gamma-ray detectors for the national RadiologicalAssistance Program teams, who are on round-the-clockalert to address nuclear accidents and emergencies.

Medical physics and radiological health research arealso key areas of study with the reactor facility. Metabolicimaging using neutrons are being carried out to signifi-cantly improve spatial resolutions and lower radiation exposures to patients compared to current nuclear

Radiation Laboratory co-director Prof. Christopher “Kim” Lister and Ph.D. student Emily Jackson set up a position-sensitive, double-sided germanium stripdetector for gamma-ray imaging. The project, a collaborative partnership with industry to investigate radiation damage in semiconductor detectors, isfunded by a Small Business Innovation Research Grant from the U.S. Department of Energy.

The Radiation Lab’s Newest Faculty Member: Andrew Rogers, Ph.D.The field of expertise of Asst. Prof. Andrew Rogers is experimental nuclear physics.

“My research focuses on the study of exotic nuclei, the role theyplay in unlocking the fundamental inner workings of the nucleus, andunderstanding nuclear processes occurring in extreme astrophysical environments,” says Rogers, who obtained his doctorate in physicsfrom Michigan State University in 2009.

“I’m particularly interested in neutron-deficient isotopes—nucleicontaining far fewer neutrons than their stable counterparts—at thelimits of nuclear stability. While exotic isotopes live only for a fraction of a second after they are produced, their properties are critical for ourunderstanding of processes that create the heavy elements in stars, in supernova explosions and in Type I X-ray bursts on the surface ofneutron stars. Much of my work is centered on learning about therapid proton-capture process, thought to take place during X-raybursts,” he explains.

To access these short-lived isotopes here on Earth, powerful particleaccelerators must be used. Rogers’ experiments are conducted at theNational Superconducting Cyclotron Laboratory (NSCL) at MichiganState University as well as other accelerators in the United States andaround the world. An upgrade to the NSCL facility—the Facility forRare Isotope Beams, with a price tag of three quarters of a billion dollars—is scheduled to come online within the next decade. “This upgrade will allow us to explore, study and discover nuclei that are cur-rently difficult or impossible to access but are key to our understandingof the cosmos,” notes Rogers.

Rogers is a hands-on experimentalist, with strong expertise and in-terest in radiation detection, instrumentation, digital electronics andsoftware. At the Radiation Laboratory, Rogers—with the help of twophysics undergraduate seniors as part of their capstone projects—recently completed the commissioning of a proton microprobe at theVan de Graaff accelerator facility. The microprobe can now deliver proton beams a few microns in diameter for a wide variety of imagingapplications, ranging from medical physics to materials science and en-gineering, using proton-induced X-ray emission techniques and digitaldata acquisition systems. n

Asst. Prof. Andrew Rogers, right, and graduate student Alvin Kow withthe proton microprobe at the Radiation Lab.

The bluish glow of Cerenkov radiation, emitted by charged particlesfrom fission traveling faster than the speed of light in water, lightsup the core of UMass Lowell’s 1 MW research reactor.

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Ph.D. student Nathan D’Olympia assembles oneof 16 detectors in a novel scintillator array(right) that detects and distinguishes betweenneutrons and gamma rays through digital pulse-shape discrimination (diagram above). The project is funded by the National Nuclear Security Agency, and the array is being deployedin-house and at national laboratories for fundamental and applied research.

Radiation Laboratory co-director Prof. Partha Chowdhury, second from left, and Ph.D. students Yuan Qiu, Sankha Hota, Emily Jackson and Vikram Prashergather around the proton irradiation chamber beam line of the lab’s 5.5 MV Van de Graaff accelerator.

medicine technologies. Identification of dosimetry exposure biomarkers can also help first responders to triage victims of radiation exposure and calculate the dose of mitigating agents that need to be administered onsite. n

uml.edu/research/radlab Assoc. Prof. Mark Tries uses the 1MWUMass Lowell Research Reactor to inves-tigate parameter optimization for high-throughput neutron activationanalysis, dose assessment for specializedreactor irradiation facilities, analysis and calibration of radiation detector response for environmental surveillanceand leakage rate for the reactor’s con-tainment vessel.

Tries had secured funding to construct a thermal neutron radiogra-phy facility within the research reactorthat can be used for the non-destructiveexamination of a wide variety of indus-trial components as well as for biologi-cal imaging. In addition, he obtainedfunding for a major upgrade of the reactor’s power and radiation monitorsto help ensure the longevity and availability of this facility.

Tries is also part of a team—withProf. Susan Braunhut in the Departmentof Biological Sciences and a faculty researcher from the Medical College of Wisconsin—that was awarded twogrants by the U.S. National Institutes ofHealth to develop ways to predict and mitigate injuries resultingfrom radiation exposure.

The first project identifies and quantifies innovative “biomark-ers” that can potentially predict radiation injuries to the lungs,weeks before symptoms become apparent. This will help doctorsin deciding on the appropriate treatment and reducing lung

injury in victims of a radiological terrorist attack, a nuclear reactor accident or in patients receiving radiation therapy for lung andbreast cancers.

The second project studies the use of the anti-hypertensiondrug lisinopril to mitigate radiation injuries to multiple organs,such as lungs and kidneys, before symptoms develop. The teamevaluates the effectiveness of the drug on laboratory test subjectsthat have been exposed to neutrons and gamma rays that mimicthe explosion of an improvised nuclear device.

Tries also have collaborated with faculty researchers in the uni-versity’s Francis College of Engineering in using radiotracers tomeasure the residence time distribution for thermoplastics in anextruder and to investigate the diffusion characteristics of a novelcation-exchange membrane.

“The UMass Lowell Research Reactor plays a major role in all these collaborations by providing the radiation fields and producing the radioisotopes necessary for investigations thathave wide-ranging impact to society,” he says. n

Radiological Health Physics A Growing Need for Radiological Sciences and Protection

Assoc. Prof. Mark Tries with a Canberraalpha/beta air monitor and a Technical Associates radiation monitor.

The thermal neutron radiography facility at the UMass Lowell Research Reactor is used as a quality assurance and R&D tool for the non-destructiveinspection of mechanical parts, electronics and assemblies.

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Medical physicists are concerned with applying physics to medicine, particularly in therapy, diagnostic imaging and nuclearmedicine. These areas employ ionizing radiation for the benefit of patients. Another area is medical health physics, which is concerned with radiation safety in a hospital setting. Qualifiedmedical physicists are graduates of accredited programs and arecertified in their specific subfields by an appropriate national certifying body.

UMass Lowell’s medical physics program offers dedicated mas-ter’s and doctoral degrees accredited by CAMPEP, the Commissionon Accreditation of Medical Physics Education Programs.

“This is the only nationally accredited program in New Englandthat leads to a doctoral degree in medical physics,” says directorProf. Erno Sajo. “We have an active research-centered student-exchange program with Heidelberg University in Germany inwhich courses and thesis research are mutually accepted. In addition, we have close research and clinical training collabora-tions with Harvard-affiliated health-care institutions, particularlyBrigham and Women’s Hospital [BWH], Dana Farber Cancer Insti-tute, Massachusetts General Hospital and Beth Israel Deaconess Medical Center, where many of their researchers also serve as adjunct faculty in the program.”

The UMass Lowell–BWH collaboration, under the direction of Sajo, Asst. Prof. Wilfred Ngwa of UMass Lowell’s Physics and Applied Physics Department and Asst. Prof. Piotr Zygmanski ofHarvard Medical School, focuses on the application of nanotech-nology to diagnostic imaging and treatment of diseases with the following concentrations.

Nanostructured Radiation Detector Development

A novel, low-cost nanofilm radiation detector invented by UMassLowell and BWH researchers uses thin-film sensors to harness theenergy of the radiation it detects to power itself. Unlike existingtechnology, the device does not need external high voltage or sig-nal amplification to operate. It is also flexible, able to conform tocurved shapes while being largely transparent to radiation, includ-ing visible light. The detector’s cost per unit area is only a fractionof that of present devices. It can detect the type and intensity ofionizing radiation as well as the location of its emission, and it

employs simple electronics to report digital signals that may bewirelessly transmitted. Nanofilms are suitable for new radiation-imaging or monitoring devices for many applications, rangingfrom national security, disaster relief and nondestructive testing to medical imaging and treatment.

“When fully developed, this device carries the potential to be atrue in-vivo implantable radiation detector that wirelessly trans-mits its signal to simultaneously tell its location in the body andthe received radiation dose in real time, while the radiation beamis targeting the tumor,” Sajo says. “In this way, organ motion will no longer impede targeting precision.”

Nanoscale Medical PhysicsFrom Low-cost Nanofilm Detectors to High-Z Nanoparticle Radiotherapies

Prof. Erno Sajo directs the university’s medical physics program. His researchinterest is the study of fundamental interactions between radiation and biological matter, with particular emphasis on cancer therapy.

The photo above shows the detector setup being developed by Profs. Sajoand Piotr Zygmanski and their team. At upper right is a calibrated radi-ographic image of the pixelated target pattern obtained with the detector.The cost to fabricate the detector array was only about $10.

High-Z Nanoparticle Research

In recent years there has been a rapid increasein the application of nanoparticles and nano-structures to medicine—from being used ascontrast agents for diagnostic imaging to potential dose enhancement in radiotherapy, to name only a few. The perturbation of the radiation field, resulting in dose enhancementor suppression near high-Z (high-atomic num-ber) materials has been known since almost thedawn of X-ray applications. Gold nanoparticles(GNPs), owing to their biocompatibility, can bedelivered to the tumor or its blood vessels with-out affecting the rest of the body. However,once the nanoparticles reach adequate concen-tration in the target, they can boost the radia-tion dose and either inactivate the neoplasticcells or disrupt the tumor’s blood supply.

“GNPs have been shown to yield significantradiation-dose enhancement when irradiatedwith low-energy X-rays,” notes Sajo. “Beforepractical applications could be developed, however, detailed computations and experi-ments of nanoparticle behavior are necessary.”

This includes characterizing the nanoparticles’dose-enhancement properties as well as under-standing their transport through the patient’s airway and bloodstream and theirbio distribution.

“Our research group has devel-oped a deterministic method to compute dose enhancement atthe nanoscale and its impact on theradiobiology of cells. This is a partic-ularly difficult task because thecomputations must be done at disparate scales, spanning seven orders of magnitude,” he says.“Separately, we have published acomputer code that can predict the coagulation of nanoparticlesen route, from the injection site to the target tissue. The signifi-cance of this research is that optimal dosimetric scenarios can befound in a methodical way as a function of irradiation conditionsand potential biological targets, which will eventually lead to realistic treatment planning methods.”

The delivery method of nanoparticles that effectively trans-ports them to the target is an active research area in which Sajo’sgroup has made significant advances. In brachytherapy, radioac-tive “seeds” or sources are implanted in or near the tumor, givinga high radiation dose to the tumor itself while minimizing exposure in the surrounding healthy tissues.

“Led by Dr. Ngwa, we introduced a method for applyingbrachytherapy to prostate cancer treatment with in-situ dosepainting, in which the seed spacers are coated with nanoparticle-containing polymer for sustained and locally controlled drug

release and subsequent radiation therapy,” he says. “We alsopioneered a similar technique in which the surface of the MammoSite balloon applicator used routinely for the treatmentof breast cancer after lumpectomy is coated with micrometer-thick polymer film to provide the same controlled drug delivery.”

Nanoparticle-aided radiotherapy for eye cancers is another application of nanotechnology in which Ngwa and Sajo and their co-researchers have been active. This work investigates the dosimetric feasibility of employing GNPs or carboplatin nanoparti-cles (CNPs) to enhance the efficacy of radiation treatment for ocular cancers, specifically retinoblastoma and choroidalmelanoma, during internal and external beam radiotherapy. The results predict that substantial dose enhancement may beachieved by employing GNPs or CNPs in conjunction with radio-therapy using kilovolt (kV)-energy photon beams. The use of thebrachytherapy approach yields higher dose enhancement thanthe external beam kV-energy devices. However, the latter havethe advantage of being non-invasive.

The team also predicted, for the first time, that by using FDA-approved concentrations of the platinum-based drug cisplatin, major radiosensitization, or enhancement, may beachieved during concomitant chemoradiotherapy (CCRT). The cisplatin is released in-situ from routinely used biomaterialsloaded with cisplatin nanoparticles.

“Our computer simulations estimate that radiotherapy dose tocancer cells may be enhanced via this mechanism by more than100 percent during CCRT,” says Sajo. n

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Profs. Wilfred Ngwa and Sajo and their research group are investigating the use of nano-particle-aided radiotherapy to help treat eye cancers, such as retinoblastoma, or cancer of theretina, which afflicts mainly young children. This panel shows retina scans of a patient’s left andright eyes with retinoblastoma (white patches) before and after chemotherapy.

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Asst. Prof. Wilfred Ngwa

Left Eye Right Eye

Assoc. Prof. Anna Yaroslavsky is the director of the Advanced Biophotonics Laboratory (ABL) at the Department of Physics andApplied Physics. She is also a visiting scientist at the Departmentof Dermatology at the Massachusetts General Hospital and Wellman Center for Photomedicine.

The ABL has state-of-the-art optical and NMR (nuclear magneticresonance) spectroscopic and imaging equipment as well as several high-performance instruments built in-house, includingtwo in-vivo multimodal confocal microscopes specifically designedfor imaging small animals and human subjects and an in-vivo polarization-enhanced reflectance/fluorescence imager.

The major focus of the research efforts at the lab is to developand integrate experimental and theoretical multimodal technolo-gies and methods for functional and structural biological tissuecharacterization, pathology detection and treatment. In particular,the research directions include:

• Integration of multiple optical imaging and spectroscopic approaches (i.e., elastic scattering, polarization imaging, fluorescence and fluorescence polarization imaging and spectroscopy) to monitor biochemical and physiological processes in real time on spatially different scales;

• Modeling of light propagation in and interaction with biological tissues, liquids and cells;

• High-precision quantitative measurements of optical properties of tissues and liquids and

• Development of all-optical and multi-modal image-guided intervention techniques.

Diagnosing Cancer at Optical Wavelengths

Recently, Yaroslavsky developed a multispectral reflectance/fluo-rescence imaging technique that enables both wide-field andhigh-resolution imaging in-vivo and in real time. The techniqueholds the potential to improve the diagnosis and treatment of malignancies, including, but not limited to, cancers of the skin,brain and breast.

The technique combines the ability of CCD macro imaging to rapidly inspect superficial tissue layers over large surfaces with confocal microscopy’s ability to take images within turbid tissuesat resolutions comparable to that of histology. The optical systemcan zoom in between these modes, allowing the wider view to direct the high-resolution view. Both modes can acquire images inreflectance, fluorescence and fluorescence polarization.

“The non-invasive system and methods we have developed inthe course of this project will enable us to identify tumor marginsand small tumor nests in-situ, which can lead to improved out-come of cancer treatments,” she says. “The diagnostic applicationof the technology can potentially replace biopsy, thus reducingmorbidity and time associated with this invasive procedure.”

Yaroslavsky uses her wide-field, high-resolution optical imaging system, which has proven to be successful in dermatological on-cology, in conjunction with a variety of dyes with specific tumoraffinity. In addition to skin cancer, she utilizes wide-field, high-resolution optical polarization imaging to identify boundaries ofinfiltrative brain tumors.

“Our goal is to improve the quality of life and survival in patients with infiltrative brain tumors,” she says. “We seek to improve the surgeon’s ability to distinguish brain from tumor on amicroscopic scale at the margins. Given the demonstrated benefitof resection for patients with a variety of intrinsic brain tumors,we hope that microscopic total resection will result in improvedoutcomes.”

Yaroslavsky is also currently collaborating with Prof. RobertGiles of the Submillimeter-Wave Technology Laboratory on imag-ing malignant and benign skin structures in the terahertz spectral range (see page 16). n

Advanced Biophotonics LaboratoryMultimodal Imaging and Spectroscopy for Medical Applications

A fluorescence confocal image (excitation wavelength = 630 nm) of a thick,fresh skin sample (size: 85 × 55 × 5 mm) with basal cell carcinoma andstained with a dye (top panel) is compared to a frozen, stained section (~5µm thick) of the same sample. The confocal image demonstrates thatstraightforward comparison with the histological section is possible.

These panels show confocal fluorescence (A) and fluorescence polarization(B) images of a skin sample with micronodular basal cell carcinoma (size:0.8 × 0.6 mm). The red arrows point to cancer cells, blue to hair follicle andyellow to inflammatory infiltrates. Comparison of fluorescence emissionand fluorescence polarization images shows that cancer exhibits higher fluorescence polarization than hair follicles and inflammatory infiltrates.

A B

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Center for Advanced Materials‘Green’ Chemistry and Engineering at UMass Lowell

Prof. Jayant Kumar, left, with research chemist Ravi Mosurkal, Ph.D., at the Center for Advanced Materials lab.

The Center for Advanced Materials (CAM) is a multidisciplinary research and resource facility for the design, synthesis, characteri-zation and intelligent processing of advanced materials in theareas of organic polymers, ceramics, biomaterials, composites,semiconductors and electro-optic materials.

Physics Prof. Jayant Kumar and plastics engineering Prof. Ramaswamy Nagarajan currently co-direct the CAM, which hasparticipating faculty researchers from the Kennedy College of Sciences, Francis College of Engineering and College of HealthSciences. The following are areas of active research being conducted by the center:

Molecular and Organic/Inorganic Hybrid Solar Cells

Materials for molecular and polymeric solar cells are synthesizedand characterized for their electronic and optical properties. Solarcells are fabricated from the materials developed, and the cells’current-voltage characteristics (efficiency, open circuit voltage andshort circuit current) and long-term stability are evaluated.

Synthesis, Properties and Applications of ‘Soft’ Materials

Polymers, small molecules and colloidal materials are synthesizedand their properties are investigated using a variety of techniques.Properties of interest include optical, nonlinear optical and elec-tronic characteristics (conductivity, electron and hole mobility) aswell as the organization of the materials in the solid state (crys-talline, liquid crystalline or amorphous) or in solution. Researchers

are interested in the optical properties of materials for their poten-tial use in fabricating optical elements and devices. Some of thematerials are designed to self-organize into micelles or vesicles insolution and have been studied as vehicles for delivering drugs.

Sensor Development and Characterization

“Intelligent” electronic sensors being investigated by CAM researchers are designed to detect chemical toxins in the air (e.g.poisonous gases, nerve agents), water (heavy metals, pathogens)and food supply as well as for health monitoring. The scientistshave also been active in developing novel sensor arrays for detect-ing traces of TNT and other explosives as tiny as one part per trillion, or even smaller.

Synthesis of Non-Halogenated Flame-Retardant Materials

The use of flame-retardant (FR) additives for making commercialflame-resistant polymers exceeds 900,000 tons per year globally.Current FR additives are often toxic and can threaten humanhealth as well as ecosystems. Research is ongoing to develop non-halogenated FR materials based on naturally occurring, sustainable materials that can be utilized as additives to rendertextiles and commercially used plastics less flammable. n

uml.edu/research/cam

Merging Science with Technology Fall 2016 uml.edu/physics

Established in 1994 by Prof. William Goodhue, now professoremeritus in the Department of Physics and Applied Physics, thePhotonics Center’s mission is to support government research, regional industries and startup companies, train undergraduateand graduate students and perform industry- and government-sponsored studies. The center’s design and fabrication capabilitiessupport various university initiatives that require innovative semiconductor-based photonic and nanoelectronic device technologies.

The Laboratory for Advanced Semiconductor Epitaxy (LASE),the main part of the Photonics Center located on the university’sEast Campus, is equipped with state-of-the-art facilities for grow-ing III–V compound semiconductor materials, fabricating devicesand characterization research.

“Our lab is currently developing a large variety of III–V material-based optoelectronics devices, thanks to the incrediblefacilities at the Photonics Center,” says Asst. Prof. Wei Guo, who heads LASE.

Photonics CenterLaboratory for Advanced Semiconductor Epitaxy

LASE researchers have also grown and fabricatedhigh-performance THz quantum-cascade lasers, orQCLs (shown with arrow), with high operatingtemperature and large output power.

High-performance InAs quantum-dot lasers are integrated with othersilicon photonics components to achieve ultra-energy-efficient andlarge-bandwidth optical interconnections.

Nanoscale highly uniform InAs quantum dots are grownself-assembled using the Photonics Center’s state-of-the-art molecular beam epitaxy systems.

Asst. Prof. Xifeng Qian, the group’s co-leader, adds: “Ourdevices will have great impact in the areas of solar energy,data centers, medical science and homeland security.”

The center’s research efforts focus on self-assembled nanomaterials, quantum dots and nanowires and their deviceapplications. These devices include InAs (indium arsenide)quantum-dot lasers for silicon photonics and medical imagingapplications, InAs and GaAs (gallium arsenide) quantum-dotnear-IR and mid-IR detectors and InGaN (indium gallium nitride) nanowire LEDs.

“Owing to unique quantum confinement effects, these devices are advantageous in many aspects compared to their bulk counterparts,” notes Guo.

LASE is working closely with other groups and researcherson campus and in other countries. At UMass Lowell, the labcollaborates with the Photonics Center’s Multiscale Electro-magnetics Laboratory (see page 15), along with the groups of Prof. Xuejun Lu and Assoc. Prof. Joel Therrien in the Electrical and Computer Engineering Department.

Quantum-cascade Laser Technology

Semiconductor quantum-cascade lasers (QCLs), due to theirhigh power and ultra-small footprint, are often used as thesources of choice at mid-IR and terahertz (THz) frequencies in multitudes of applications, ranging from health-care andpollution monitoring to homeland security.

A collaborative project between the Photonics Center andUMass Amherst, NASA’s Jet Propulsion Laboratory and theGerman Aerospace Center (DLR) aims to build a sensitive,

compact coherent THz heterodyne transmitter/receiver systembased on THz QCLs and Schottky diode balanced mixers. TheUMass Lowell part of the project is directed by physics Lec-turer Andriy Danylov, Ph.D., and Prof. Emeritus Jerry Wald-man. University researchers have demonstrated significantimprovement in spatial and temporal coherency of THz QCLs,which opens the door for applications of the system in THz astronomy, imaging, spectroscopy and plasma diagnostics. n

Asst. Profs. Wei Guo, left, and Xifeng Qian work in the Photonics Center’s Laboratory for Advanced Semiconductor Epitaxy (LASE), which is currently developingindium arsenide (InAs) quantum-dot lasers for silicon photonics and medical imaging applications.

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Laboratory for Nanoscience and Laser Applications

“We are using intensive pulsed laser light to study interactionsbetween laser pulses and matter for potential applications innanoscience and nanotechnology,” says Assoc. Prof. MengyanShen, head of the Lab’s Femtosecond Laser Group. The team utilizes a femtosecond (10-15 sec.) pulsed laser at 400 and 800nanometers (nm) to fabricate nanostructures on a solid surface.

“The technique is highly efficient because it is several ordersfaster than electron-beam writing and ion-beam etching, and isapplicable to different materials,” he says. “It has applications in opto-electronics such as high-efficiency photodetectors andsolar cells, as well as in biology and medical research such asmicro/nano tunnels for low-friction fluidity, and nanostructuredmetal surfaces for other applications.”

The group has successfully developed soft nanolithography to three-dimensionally replicate silicon nanospike structures madeby femtosecond laser pulse irradiation to a precision of 5 nm.

The replicated nanostructures are being used to manufactureidentical chemical and gas sensors at very low cost. This researchhas been supported by the National Science Foundation (NSF).

“With metal nanostructures formed with femtosecond laser irradiation, a natural-like photosynthesis has shown great potential for storing solar energy and saving our environment,”says Shen.

This research has been partially supported by a seed fund from the NSF Center for High-Rate Nanomanufacturing at UMass Lowell.

He says the group is also developing techniques for time-resolved spectra measurements, in the time range from secondsto femtoseconds, for other applications in nanoscience and nanotechnology. n

uml.edu/research/nanosciencelab

Creating Nanostructures on Solid Surfaces Using Femtosecond Pulsed Laser

Assoc. Prof. MengyanShen (right) and graduate student Cong Wang workon the lab’s laser setup.

The sequence above shows the formation of siliconnanospikes on a silicon surface irradiated in distilled waterby an increasing number (from blue to red) of femtosecondlaser pulses. The nanospikes in the background are about 100 nanometers wide and up to about one micrometer high.

Recent developments in fabri-cation and metrology have enabled scientists to create anew generation of complexnanostructured materials. Re-search being conducted at theuniversity’s Multiscale Electro-magnetics Laboratory focuseson understanding light interac-tions with these materialsthrough advanced analyticaland computational studies.

“Some of the fundamentalproblems we are trying to solveinclude confinement and manipulation of optical pulses at the deepsubwavelength scale,” says Prof. Viktor Podolskiy. “We are also interested in computational optics and imaging.”

Engineered composites open fascinating opportunities in moldingthe flow of light at the nano- and micro-scale.

“Optical properties of these composite structures, or metamateri-als, depend not only on the electromagnetic properties of their constituents, but also on the arrangement and shapes of their components,” explains Podolskiy.

A subclass of metamaterials, gold nanowire arrays are rapidly becoming flexible platforms for high-performance optical applica-tions in biosensing and opto-acoustics as well as for experimentaldemonstrations of novel physical phenomena that include negativerefraction of light and anomalous transmission. However, despitesignificant previous research, the physics behind the counterintuitiveoptics of nanowire arrays has not been completely understood.

“Over the past several years, our group has collaborated closelywith the group of Prof. Anatoly Zayats from King’s College Londonin trying to uncover the origin of the unusual optical response oftenseen in experiments,” Podolskiy notes. “We now have a workingmodel that not only quantitatively describes the optics of nanowire

structures, but also reveals how the observed optical response stems from the interaction of light with the collective oscillation of free-electron plasma propagating inside the metallic wires. Ourwork, pushed forward by Brian Wells, a graduate student at UMass Lowell’s Physics Department, paves the way for understanding emis-sion and absorption of light by these fascinating complex materials.”

Podolskiy’s group also explores opportunities in developing novelimaging techniques, opened by the exponential growth of computa-tional processing power and fueled by Moore’s law. Recent develop-ments in optical technology allowed drastic reduction in physical sizeand weight of consumer photo and video cameras. Unfortunately,the same technology cannot be used to reduce the size of camerasand radars working at longer wavelengths. These imaging systems,which have multiple applications in night-vision technology, pollu-tion monitoring, safety, security and fundamental science, remainrelatively bulky and expensive.

“One of the factors that limit the size of a camera is the size ofthe pixel on its imaging sensor,” explains Podolskiy. “In conven-tional, lens-based systems, the size of this pixel is determined by the wavelength of light in the vacuum. Longer wavelength meanslarger pixels, which in turn means larger sensors, lenses, camerabodies, etc.”

Pixel size, however, can be dramatically reduced in materials with larger index of refraction.

“In our recent work, we demonstrate that replacing lenses withdiffraction, or grating-type, elements along with the incorporationof high-refractive-index materials allows one to reduce the size of in-dividual pixels and potentially create much-smaller, long-wavelengthcameras,” he says. “As an added benefit, diffraction-based systemsallow one to restore volumetric image of the surroundings—similarto hologram—based on a single exposure. Sandeep Inampudi, agraduate student in the department, is now working on exploringthe limitations of diffraction-based imaging.” n

uml.edu/research/multiscale-electromagnetics

Multiscale Electromagnetics LaboratoryStudying Metamaterials and their Interactions with Light

Prof. Viktor Podolskiy

A beam of laser excites a slab of uniaxial metamaterial, formed by an array ofaligned metallic wires (left). The resulting oscillation of electrons in the wiresexcites two fundamentally different optical modes with identical polarization—a plasmon-like wave where electrons oscillate perpendicular to the wire and a polariton-like longitudinal mode where electrons oscillate along the wire (shown at right).

Diffraction element uses the radiation emitted by the seven-source scene toproduce highly oscillatory pattern (left), with subwavelength peak-to-peak distance. This pattern is detected by the sensor (center) and used by the numerical imaging algorithm to reproduce the light distribution in the original scene (right).

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For the past 30 years, UMass Lowell’s Submillimeter-Wave Technology Laboratory (STL) has been at the forefront of terahertz(THz) transmitter and receiver technologies and has pioneered in designing and fabricating broadband solid-state multipliersources, high-power ultrastable CO2 and far-IR lasers, andlaser/microwave hybrid systems. The lab has developed and applied these technologies in the areas of military surveillance,homeland security, medical diagnostics and scientific and academic research.

At the heart of the facility is a staff of 20 full-time researchersand 40 graduate and undergraduate students. Together they design, build and maintain a variety of high-performance solid-state and laser-based measurement systems and implement anumber of novel techniques for simulating microwave radarmeasurements in a laboratory environment.

“Our staff represents scientists and engineers of every university discipline, and every aspect of our investigative studiesrequires interdisciplinary collaborations,” says STL director Prof.Robert Giles.

From the Lab to the Battlefield

In 1979, then-STL director (now science adviser) Prof. Jerry Waldman recognized that emerging THz-frequency source/receiver technologies could be used to simulate the military’s sophisticated microwave radar systems in the laboratory to obtaincharacteristic radar fingerprints of aircraft, ships, tanks, trucks andother tactical vehicles at low cost and very high accuracy. The con-cept of radar scaling is embedded in the basic equations of elec-tromagnetism and is similar to, but more exact than, aerodynamicscaling, where wind tunnels are employed with model aircraft.

Researchers at the lab spent more than a decade engineeringand fabricating scale versions of the military radars and high-precision models of actual targets, as well as measuring and analyzing the resulting radar backscatter. To reduce backgroundstray scatter, the lab developed a unique anechoic material called FIRAM™, which is vastly superior to other materials at submillimeter wavelengths.

“As a member of ERADS, the Expert Radar Signature Solutionsconsortium developed by the Army’s National Ground Intelligence

Submillimeter-Wave Technology LaboratoryResearch Center Offers Breakthroughs in Terahertz Imaging

Terahertz scientist Jason Dickinson works on one of the Submillimeter-Wave Technology Laboratory’s powerful carbon dioxide lasers.

Scaling the acquisition of radar-signature data requires realistic modeling of the ground terrain as well as fabricating precisely scaled replicas of tactical vehicles. A significant portion of STL’s efforts concentrate on building precision scale models of a wide variety of vehicles. The lab’s success also relies on carefully designed metallic and non-metallic coatings and structures that are added to the models to simulate the full-scalevehicle’s radar-scattering behavior. STL produces comprehensive libraries of target radar signatures of vehicles for use by agencies developing automated target-recognition systems.

Actual Tank Scale Model Radar Image

STL Engineering Director Michael Coulombe works on a solid-state, high-resolution THz radar system.

Center [NGIC], we and our government sponsors are the only research program that uses terahertz-frequency measurement sys-tems to collect real-world radar signature data,” says Giles in ex-plaining the lab’s unique position. ERADS also includes researchersat the Aberdeen Proving Grounds and the University of Virginia.

Today, the lab’s high-resolution THz imaging systems are sosensitive that, based on the radar signatures, they can distinguisha target’s non-metallic materials (rubber, fiberglass and canvas) ordetect the target’s presence on desert, soil, asphalt, concrete andother terrains amid ground clutter found in actual military opera-tions (troop packs, ammunition crates, fuel containers, etc.).

To help fund STL’s research, in 2001 the NGIC awardedthe lab a five-year, $27 million contract—the largest sin-gle award ever given to UMass Lowell. And in 2011, the

agency awarded a renewal grant to the lab worth $23 millionover five years.

In addition to its work for the Army, the lab has used its unique capabilities to fulfill radar measurement requests fromother Department of Defense agencies as well as defense-related laboratories and companies, including MIT Lincoln Lab, Boeing,Lockheed-Martin and Raytheon. n

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STL is leveraging its expertise in terahertz technology to develop advanced imagingsystems to detect objects such as weapons and explosives hidden under clothing.

Merging Science with Technology Fall 2016 uml.edu/physics

The Biomedical Terahertz Technology Center (BTTC) was estab-lished in 2012 with the goal of translating the extensive terahertz(THz) technology expertise at UMass Lowell to biomedical applica-tions (see page 16). THz radiation, which lies between the mi-crowave and infrared regions of the electromagnetic spectrum, ishighly sensitive to water content in tissues and, unlike X-rays, isnon-ionizing. THz imaging has been shown to offer intrinsic con-trast—i.e., no external contrast agent is needed—between normaland cancerous tissues, making it well-suited for biomedical imag-ing, especially for studying colorectal cancer and non-melanomaskin cancer.

Colorectal cancer is the third most common cancer in theUnited States, with approximately 140,000 new cases each year.Early diagnosis and surgical removal of benign neoplastic lesions isan effective method for reducing a patient’s cancer risk and pre-venting cancer-related death. The current standard for screening isconventional colonoscopy, which relies on visual inspection of thelining of the intestine.

The BTTC, in collaboration with Dr. Karim Alavi in the Divisionof Colorectal Surgery at UMass Medical School in Worcester, isevaluating the tissues’ intrinsic contrast, combining it with thecenter’s existing efforts on THz waveguide development.

“We have shown that polarized THz images can differentiatebetween healthy and cancerous tissues,” notes UMass Lowellphysics Prof. Robert Giles, the center’s director. “This technique

potentially offers surgeons a tool to aid in colon-cancer screening.”

Going More than Skin-Deep

Non-melanoma skin cancer accounts for half of all cancers in theU.S. Of the more than 3.5 million cases diagnosed each year,about 3,000 patients die from the disease. And the cost of treat-ments exceeds $600 million annually.

The most effective treatment usually involves Mohs micro-graphic surgery, in which the tumor is removed by excising the tis-sue layer by layer, with each layer examined under a microscopeto help map the diseased area. This ensures the complete removalof the tumor while preserving much of the surrounding normaltissue. While the procedure is effective, it is time-consuming,labor-intensive and costly.

Although THz imaging offers intrinsic contrast, its resolution islimited in wavelength to approximately 0.5 millimeter. Imagingwith optical polarized light offers higher resolution (comparable tohistology) but lacks the contrast. BTTC researchers are collaborat-ing with UMass Lowell physics Assoc. Prof. Anna Yaroslavsky ofthe university’s Advanced Biophotonics Laboratory (see page 10)to develop a non-invasive multi-modal optical/THz imaging systemfor non-melanoma skin cancer that would complement currenttreatment techniques and aid in the demarcation of cancer margins. n

Biomedical Terahertz Technology CenterDeveloping Innovative Imaging Technology for Cancer Diagnosis

Graduate student Jillian Martin works on the BTTC terahertz optical systems used for biomedical imaging.

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A team of scientists, engineers and students in the university’s Lowell Centerfor Space Science and Technology (LoCSST) directed by Prof. SupriyaChakrabarti is conducting research tostudy Earth, other Earthlike exoplanets,the Milky Way galaxy and the cosmos.

“The center aims to train the nextgeneration of scientists and engineersthrough hands-on involvement in allphases of the mission, from instrumentdevelopment to data analysis,” saysChakrabarti. “We will also mentor andtrain early career professionals in spaceastronomy and engineering and promotehands-on undergraduate participationin space and technology research.”

In 2014, NASA awarded Chakrabartia grant worth nearly $5.6 million overfive years to develop and test an instru-ment system that could potentially de-tect young, Jupiter-size planets orbitingother stars in the Milky Way. The team’sultimate goal is to discover Earth-likeplanets around sun-like stars capable of supporting life.

The instrument—dubbed the Plane-tary Imaging Concept Testbed Using a Recoverable Experiment –Coronagraph, or PICTURE C—is scheduled to be launched on twoseparate flights, in the fall of 2017 and 2019, from the ColumbiaScientific Balloon Facility in Fort Sumner, N. M., where it would becarried aloft to the edge of the atmosphere using helium balloonsseveral stories tall.

“PICTURE C will enable us to learn about the disk of dust, asteroids, planets and other debris orbiting the stars and gain abetter understanding of the processes and dynamics that formedour own solar system,” explains Chakrabarti, who is the principalinvestigator for the NASA study. “But in order for us to do this,we have to fly the instrument to altitudes of about 120,000 feetto get above most of the Earth’s atmosphere. Atmospheric turbulence distorts and blurs our image of the stars.”

Aside from Chakrabarti, the other members of the UMass Lowell team are physics Asst. Prof. Timothy Cook, who is the project’s co-investigator; graduate student Kuravi Hewawasamand post-doctoral associates Susanna Finn and ChristopherMendillo. Other collaborators include researchers from NASA’s Jet Propulsion Laboratory and Goddard Space Flight Center, Caltech, MIT, the Space Telescope Science Institute and the University of California Santa Barbara.

Employing Cutting-Edge Technologies

Five stars have been selected as test targets for the two missions,representing a wide range of brightnesses, ages, distances andspectral types: Alpha Lyrae (Vega), Sigma Draconis, Epsilon Eridani, Alpha Aquilae (Altair) and Tau Ceti.

The mission will allow PICTURE C to test its coronagraph, aspecialized optical imaging system coupled to a 24-inch-diametertelescope designed to “mask,” or block out the direct light fromthe star so that faint objects very close to the star—such as plan-ets, asteroids and interplanetary dust, which otherwise would behidden in the star’s bright glare—can be studied in great detail.

The scientists expect the instrument to be rocked by turbulence in the upper atmosphere. To keep the coronagraphaimed precisely at the target, the instrument is mounted on a special gimbal platform in the balloon’s gondola that can compensate for any unwanted movements. PICTURE C will use the platform in conjunction with an onboard active opticalpointing control system.

“Chris Mendillo designed and built this fine-pointing systemand had validated it on an earlier mission,” notes Chakrabarti. “Itcan provide the coronagraph a pointing accuracy of 5 milliarcsec-onds, which is comparable to that of the Hubble Space Telescope,or even better.”

Lowell Center for Space Science and TechnologyResearchers Use Sounding Rockets and Balloons to Explore the Cosmos

Asst. Prof. Timothy Cook, right, and post-doctoral associate Christopher Mendillo prepare an earlier versionof the PICTURE C payload, which was flown in 2011 aboard a sounding rocket.

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To the Threshold of Space

The researchers have also used sounding rockets to lift instru-ments weighing more than 1,000 pounds to altitudes of up tomore than 900 miles above the ground. These rockets are notpowerful enough to boost their payload to orbital speed—afterscientific observations have been completed, the payload fallsback to Earth, deploying a parachute to slow down its descentand allow for a safe recovery of the payload on the ground.

“Prof. Cook and I havea combined 40 years of ex-perience launching experi-ments aboard soundingrockets, and we have suc-cessfully launched 20 ofthem during that timespan,” says Chakrabarti.

For example, in Novem-ber 2012 Cook launchedanother NASA-funded in-strument, called IMAGER,aboard a sounding rocketto observe the spiral galaxyM101 and measure theproperties of its dust. Cookand his team are now analyzing the data from the IMAGER flightto understand how ultraviolet light is absorbed by the dust, how itheats and destroys the dust and how new dust is formed.

Sounding rockets and high-altitude balloons offer a relativelyinexpensive way to verify the flightworthiness of the science hardware before they are placed into orbit, which costs tens ofmillions of dollars per launch. However, scientific observationsaboard sounding rockets are limited to about seven minutes or so before the rocket’s payload falls back to the ground.

“For some experiments, the several hundreds of seconds ofdata from above the atmosphere that a sounding rocket providesare just not enough,” explains Chakrabarti. “In the case of PIC-TURE C, a high-altitude balloon offers a better way to lift the instrument to the threshold of space—above 99 percent of the atmosphere—and keep it aloft for hours or days, depending onthe weather conditions as well as the launch site, the type of balloon, the time of day, etc.”

At the end of the mission, ground controllers would send acommand to release the payload from the balloon, and the payload free-falls to the ground. A parachute is then deployed to slow it down and allow the payload to land gently for reuse in the next mission. n

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The new NASA-funded PICTURE C science experiment will be launched intothe stratosphere in 2017 and 2019 on two high-altitude balloon flights. They will be the first balloon missions for UMass Lowell.

The face-on spiral galaxy M101 in UrsaMajor, shown in this photo taken by theHubble Space Telescope, was the target ofAsst. Prof. Timothy Cook’s rocket experi-ment in 2012.

Prof. Cook, fifth from left, poses with Supriya and Joanne Chakrabarti,Meredith Danowski, Christopher Mendillo, Brian Hicks, Jason Martel andEwan Douglas at the White Sands Missile Range in New Mexico. In the background is the Black Brant IX sounding rocket used in the 2012 launch.

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EXCEL is a multi-campus center sponsored by the UMass Science &Technology Initiatives Fund. EXCEL’s mission is to develop and usestate-of-the-art lidar (light detection and ranging) technologies forresearch and environmental applications relating to forestry, coastalwetland mapping, coastal changes and offshore wind and turbu-lence. The center will also provide field-mapping and data-analysisservices to both public and private sectors.

The EXCEL team brings together existing expertise and resourceswithin the UMass system (Lowell, Amherst, Boston and Dartmouthcampuses), while leveraging its collaborations with industry and government partners to further develop advanced lidars for environ-mental remote-sensing.

“This effort will be supported by a comprehensive data-analysisand synthesis infrastructure. In addition, we will develop prototypesand test and evaluate new sensors and instrument technologies,”says UMass Lowell physics Prof. Supriya Chakrabarti, the center’s director.

EXCEL will utilize lidar technology to address the following criticalareas of interdisciplinary environmental sensing:

Terrestrial ecology. Terrestrial lidar has been used in many appli-cations, particularly in monitoring forests and the erosion of geo-logic bluffs as well as in verifying carbon biomass. A team assembledby Chakrabarti and Asst. Prof. Timothy Cook of UMass Lowell inconjunction with UMass Boston and Boston University has been atthe forefront of research in this field. The team is currently complet-ing the field-testing of the Dual-Wavelength Echidna Lidar (DWEL)funded by the National Science Foundation (NSF). DWEL operates at1064 and 1548 nanometers to separate woody biomass from pho-tosynthesizing foliage and provides 100-meter hemispherical scansof forest canopy structures.

Oceanographic applications. Oceanographic bathymetric lidarcan be applied to the problem of sediment-transport processes associated with coastal change and sea-level rise.

“Coastal erosion both as a chronic issue associated with rising sea levels as well as due to major events such as Hurricane Sandy in 2012 or the Blizzard of 2013, will have increasing impact on theCommonwealth’s economy,” notes Chakrabarti.

A team led by UMass Dartmouth that includes Profs. Cook andChakrabarti is developing critical tools in the maintenance, restora-tion and protection of the state’s coastline, with broader impacts to all coastal regions facing sea-level rise and coastal change.

Wind energy generation. Wind-turbine aerodynamics directlycontributes to efficiency and reliability. One of the biggest challengesis characterizing the turbines’ aerodynamic behavior, which isneeded to better understand their fundamental behavior. The use of atmospheric lidar to quantitatively characterize the wake of full-scale wind turbines would eventually lead to improved designs of turbine and commercial scale wind farms.

UMass Lowell mechanical engineering Assoc. Prof. David Willisand Cook are leveraging existing research efforts in wind energy at the Lowell and Amherst campuses to become a leading environ-mental sensing and impact-assessment resource in the field. UMassLowell recently received funding from the NSF to establish an Indus-try/University Cooperative Research Center for Wind Energy Science,Technology and Research (WindSTAR). n

EXCEL: An Experimental Center for Environmental LidarApplications in Terrestrial Ecology, Oceanographic Bathymetry and Aerodynamics

A team of UMass Lowell students and faculty researchers have used theground-based, portable Dual-Wavelength Echidna Lidar (DWEL) instrument forfield campaigns in Australia, California and Massachusetts (shown here). DWELuses infrared laser light to scan a three-dimensional image of the forest envi-ronment. This allows the team to study the structure and health of the forestand determine the carbon biomass of the area under study.

From left: Students Saurav Aryal, Schayne Lees and Glenn Howe prepare theDWEL unit for deployment. The instrument is battery-powered and mounts on a tripod for easy transport and set up.

Merging Science with Technology Fall 2016 uml.edu/physics

The focus of the Astronomy and Astrophysics Group is the multi-wavelength (infrared, optical andX-ray) study of accretion-poweredX-ray binaries, or XRBs. These fasci-nating star systems consist of acompact companion (neutron staror black hole) and a normal starlocked in orbit around each other.The normal star is slowly consumedby its companion, whose stronggravity is able to capture gas fromthe star and then crush it to nu-clear density, releasing tremendousamounts of energy in the process.As a result, the compact objectshines brightly in X-ray as it feeds.

“By observing the X-ray emis-sion, we can study fundamental astrophysical properties that areunobtainable at other wave-lengths,” says Silas Laycock, Ph.D.,an assistant professor in the Department of Physics and AppliedPhysics and the group’s leader. “Meanwhile, optical spectroscopyenables us to study the stellar companion and trace its orbital motion. X-ray binaries simultaneously probe extreme physics andprovide a unique window into stellar and galactic evolution.”

One of the group’s projects is a time-domain survey of X-raypulsars—spinning neutron stars whose magnetic fields channelthe accretion stream to their poles and emit regular pulses as their X-ray beams rotate around the sky.

“Using thousands of satellite observations of about a hundredknown X-ray pulsars accumulated over more than a decade, weare building the most comprehensive library of pulse profiles,”notes Laycock. “By developing computer models of the pulsars’beams and matching them to the X-ray data, we will shed lighton the structure of the magnetospheres of neutron stars and their dramatic changes over time.”

Black holes and neutron stars are the relics of the most massiveand short-lived stars—the same stars that die in supernovae—which sculpt and enrich the interstellar medium and create thechemical elements needed to seed life. These natural particle ac-celerators are visible in X-rays at intergalactic distances. The groupis using X-ray astronomy satellites (NASA’s flagship Chandra X-rayObservatory and Europe’s XMM-Newton) along with optical tele-scopes (such as the 8-meter Gemini telescope) to discover andmonitor X-ray binaries in nearby dwarf galaxies.

“Different galaxies seem to have produced XRBs in large num-bers, but at different points in their evolution, and curiously thesebinaries involve different types of stars and different ratios ofblack holes to neutron stars,” Laycock explains. “By studyinggalaxies of different ages all the way down to the very youngest—a mere few million years—we are unlocking the secrets of whathappens in this brief but influential period of star formation.” n

Astronomy and Astrophysics GroupX-Ray Binaries as Astrophysical Probes, Multi-wavelength Observations and Time-domain Astronomy

An artist’s impression of the Cygnus X-1 binary system. It shows a massive OB or Be star, at left, losing matterto a compact companion (a black hole or neutron star) and forming an accretion disk around the companion. Matter in the inner disk is heated to millions of degrees, generating the X-rays observed from Earth.Illustration courtesy of ESA/Hubble.

The Astronomy and Astrophysics Group—led by Asst. Prof. Silas Laycock,shown in the photo at left with undergraduate student Kathleen Oram andgraduate student Andrew Balchunas—is interested in high-energy astro-physics, time-domain analysis and data-intensive astronomical research.

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Established in 2014, Space Science Laboratory (SSL) continues theUMass Lowell heritage of conducting scientific investigations inspace weather, magnetospheric physics, ionospheric physics andradio science. Through research grants from NASA, the NSF, AirForce Research Laboratory and NATO, the SSL has developed strongengineering expertise in designing autonomous remote-sensing systems for spacecraft platforms. Computer scientists at SSL alsobuild intelligent systems for automatic interpretation of acquireddata and operate the Global Ionospheric Radio Observatory (GIRO), a worldwide network established in 1969 to conduct radio-wave experiments in Earth’s ionosphere using radar-sensing instruments,or “digisondes.” For more information, go to http://giro.uml.edu.

Other fields of research include:

Very low frequency in space.A self-tuning VLF transmitter willdrive an 80-meter dipole antennaonboard the U.S. Air Force ResearchLaboratory’s DSX satellite to studythe effects of space plasma on theradiation process as well as the ef-fects of the radiation on the trappedelectron population. SSL scientistsdesigned the power transmitter anda narrow-band receiver in coopera-tion with the Southwest Research Institute and Stanford University. The system will measure the localplasma density and automaticallytune the antenna circuit for maxi-mum radiation.

Plasma modeling and simulation. Ground-based andspace-borne observations have established a global picture of thespace-plasma environment. The modeling and simulation, combinedwith observations, has proven to be a powerful tool for understand-ing the physical and chemical processes in space plasma and in predicting space weather. The SSL undertakes empirical modelingand computer simulation of antenna-plasma interaction, magnetosphere-ionosphere-thermosphere coupling, ionosphere and magnetosphere density distribution and plasmasphere depletion and refilling.

“Killer” electrons. Featured at #37 in Discover magazine’s “Top 100 Science Stories of 2007,” the discovery of the physicalmechanism responsible for accelerating electrons trapped in Earth’sVan Allen radiation belts to “killer” velocities—as much as 94 per-cent of the speed of light—has been credited to SSL researchers.

Space weather. This is an emerging field of research that appliesknowledge gained in space physics and space-plasma physics toforecast weather conditions in space. Constellations of satellites areto be launched into strategic orbits and global computer-simulationcodes are being developed. The Space Science Lab has developedmodels that are being used in the National Space Weather Services.

NECTAR. The Non-linear Error-Correcting Technique for Associa-tive Restoration employs recurrent neural network optimizer to inferglobal picture of dynamic processes in plasma from the availablefragments.

GAMBIT. The Global Assimilative Model of Bottomside Ionos-pheric Timelines is a database of past space-weather events thatprovides a detailed look at ionospheric plasma dynamics during the most interesting periods of the Sun–Earth system activity. n

http://ulcar.uml.edu

Space Science LaboratoryInvestigating Space Weather, the Magnetosphere and Ionosphere

SSL Director Paul Song and Assoc. Director Ivan Galkin work with former doctoral student Meg Noah during a full functional test of the flight software for the UMass Lowell-designed high-power VLF transmitter. The transmitter will be flown into Earth’s Van Allen radiation belts aboard the Air Force Research Laboratory DSX spacecraft to conduct wave-particle interaction experiments.

NASA’s IMAGE mission (2000 to 2005) flew a UMass Lowell-designed Radio Plasma Imager instrument for remote sensing ofEarth’s plasma using a unique spinning antenna system with two 500-meter dipoles.

The Global Ionospheric Radio Observatory (GIRO) is comprised of 130 SSL-designed and built high-frequency radio-sounder installations in 27 countries,with real-time access to observational data from 45 locations. The data arestored and analyzed at the Lowell GIRO Data Center, which now holds morethan 40 million radio-sensing observations.

Merging Science with Technology Fall 2016 uml.edu/physics

Nishant Agarwal, Ph.D., Cornell University, 2011Theoretical cosmology

Supriya Chakrabarti, Ph.D., University of California,Berkeley, 1982Astronomy and astrophysics

Partha Chowdhury, Ph.D., SUNY Stony Brook, 1979Graduate Program CoordinatorNuclear structure, detector development, applied nuclear science

Ofer Cohen, Ph.D., University of Michigan, 2008Computational plasma physics, magnetohydrodynamics

Timothy A. Cook, Ph.D., University of Colorado, 1991Astronomy and astrophysics

Andriy Danylov, Ph.D., UMass Lowell, 2010Photonics

Robert H. Giles, Ph.D., UMass Lowell, 1986Department ChairExperimental laser physics, optics

Wei Guo, Ph.D., Brown University, 2008Nanomaterial growth, optoelectronic device applications

Archana Kamal, Ph.D., Yale University, 2013Quantum physics, quantum information

Jayant Kumar, Ph.D., Rutgers University, 1983Materials science, optoelectronic properties of materials, optical spectroscopy

Silas Laycock, Ph.D., University of Southampton, 2002Astronomy

Nikolay Lepeshkin, Ph.D., New Mexico State University, 2001Undergraduate Program Coordinator

Optics

Arthur Mittler, Ph.D., University of Kentucky, 1970Experimental nuclear physics, physics education

Wilfred Ngwa, Ph.D., University of Leipzig, 2004Biophysics, medical physics, health physics

Viktor A. Podolskiy, Ph.D., New Mexico State University, 2002Department Assistant ChairElectromagnetism, photonics, nanoscience, metamaterials

Xifeng Qian, Ph.D., UMass Lowell, 2009Photonics

Andrew Rogers, Ph.D., Michigan State University, 2009Nuclear astrophysics, nuclear structure

Erno Sajo, Ph.D., UMass Lowell, 1990Medical Physics Program CoordinatorNuclear science, medical physics

Kunnat Sebastian, Ph.D., University of Maryland, 1969Particle physics theory, theoretical atomic physics

Mengyan Shen, Ph.D., University of Science and Technology of China, 1990Nanoscience and technology, condensed matter and optics

Paul Song, Ph.D., University of California, Los Angeles, 1991Space Physics

Mark Tries, Ph.D., UMass Lowell, 1999Radiological Science Program CoordinatorRadiological science and protection

Anna N. Yaroslavsky, Ph.D., Saratov State University, Russia, 1999Biophysics, medical physics, optics, photomedicine

Johannes Zwanikken, Ph.D., Utrecht University, Netherlands, 2009Condensed matter theory, soft matter

The mission of the university’s Haiti Development Studies Center(HDSC) is to engage science and engineering faculty and studentsin philanthropic research focused on solving life-threatening issuesfaced by citizens in the world’s poorest countries.

“These countries, identified by the international banking sys-tem as having Third- and Fourth-World status, suffer from over-population, soil erosion, drought and famine,” says Prof. RobertH. Giles, the center’s director. “However, the lack of potable waterand sufficient food supplies are not the only barriers to economicdevelopment in the most densely populated regions of the world. Fragmented politically and socially, the general population in theselabor-rich countries face environmentally induced health issuesdue to chemical and biological contaminants in the air, water, soiland locally grown food.”

Whether human-caused or naturally occurring, these contami-nants are crippling communities in impoverished countries.

“They are compromising the health of the indigenous popula-tion, defeating foreign investment for positive change and eliminating possible global participation of the local work force,”notes Giles. “Only treating the contaminant-induced societalsymptoms, international aid agencies developing programs tosupport public work’s projects and medical clinics are often ex-hausted before sustainable change occurs in the poorest regions.”

In response, Giles established the HDSC in 2013 in the port city of Les Cayes in Haiti, which he describes as a Fourth-Worldcountry with First-World possibilities.

“I believe Haiti has First-World potential by virtue of its geo-graphical location in the Caribbean,” explains Giles, who has

more than 10 years of experience working in Haiti and is nowfairly fluent in Creole. “Having a permanent residence within thecommunity will enable visiting UMass Lowell faculty and studentresearchers to perform health and environmental assessmentsacross the Southern Department of Haiti.”

The HDSC employs a full-time staff comprised of an Americanprogram coordinator, Connie Barna, who resides in the facility,and a six-member team of Haitians who are responsible forhousekeeping, ground transportation, security and all in-countryresource requirements.

Giles and Barna advise on projects involving regional and com-munity-based concerns and opportunities while university studentinterns and their faculty advisers may remain in Haiti over ex-tended periods to gather and document the scientific data.

Life-saving Research

With a focus on scalable and sustainable technologies for impov-erished regions of the world, faculty and students at the centerare developing programs to decrease the impact of environmentalcontaminants and assess the efficacy of those programs.

Projects being undertaken at the center include:

• Implementing bio-sand water-filtration systems as well as in-vestigating pilot studies to identify biomarkers for recognizingcontaminated water;

• Developing low-cost, spectroscopic monitoring techniques andthe instrumentation for supporting laboratory analysis;

• Investigating affordable solar energy systems and recycling ofcombustible waste materials as biomass fuels;

• Establishing a directed-studies, college-preparatory programfor select Haitian students in the physical sciences with service-based team training on engineering projects and laboratory skills and

• Conducting an Honors College Seminar Series for science andengineering students focused on impoverished countries and theprocess of developing international research projects to explorescalable and sustainable solutions that address regional concerns.

“As an at-home and abroad program, internationally collabo-rative research projects not only challenge the critical thinkingskills of our students, but also raise their awareness of socio-eco-nomic and regional factors that hinder positive world change,”says Giles.

He adds: “Education is central to our mission. For students andteachers, the opportunities to make a difference in people’s livesare limitless. The center is a place where research is a pathway tocritical change.”

For more information on how to help the Haiti DevelopmentStudies Center, e-mail Giles at Robert_Giles@uml.edu. n

Haiti Development Studies CenterMaking Positive Change in the Impoverished Caribbean Nation

For more information, visit:

uml.edu/physicsOr contact:

Prof. Robert H. GilesChair, Department of Physics and Applied PhysicsPhone: 978-934-3779E-mail: Robert_Giles@uml.eduOlney Science Center 136CUniversity of Massachusetts LowellOne University AvenueLowell, MA 01854

Prof. Robert Giles teaches schoolchildren in Les Cayes, Haiti, how to build asimple telescope out of cardboard tubes and lenses as part of the Haiti Development Studies Center’s astronomy education outreach.

Merging Science with Technology Fall 2016

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Physics Faculty and Expertise