Experimental Researchers, known as experimentalists in physics and observers in astronomy, carry out and utilize measurements to quantify the properties of nature and to evaluate the viability of hypotheses about the workings of nature. For example, experimental atomic physicists have developed instrumentation and techniques to create and trap antihydrogen (a positron bound to an antiproton) to determine whether or not its energy levels are spaced identically to those of normal hydrogen, as predicted by the Standard Model. Experimental particle physicists used the Large Hadron Collider to detect the Higgs boson, the existence of which had been postulated to explain how subatomic particles have acquired mass. Observational astronomers employed telescopes to determine accurate distances to supernovae in distant galaxies, thereby revealing that the expansion of the Universe is accelerating and that the predominant constituent of the Universe is dark energy.
Here are the Experimental Researchers who are able to supervise graduate students. To see a detailed profile of anyone, including contact information, click on the title bar or portrait. To see a personal research website (if available), click on the research picture.
Supernovae and their remnants; Pulsars; Active Galactic Nuclei; Observational tests of general relativity; Radio continuum astronomy; Very Long Baseline Interferometry.
I study galactic and extragalactic compact, celestial sources of radio waves such as supernovae, pulsars, black hole candidates, radio stars and the powerful cores of radio galaxies and quasars. With the technique of very-long-baseline interferometry (VLBI) and a network of several large radio telescopes girdling the globe, it is possible to image the areas of activity of these sources and determine their positions with an angular resolution 1,000 times better than with any optical telescope on Earth. In particular, this allows us to make sequences of images of young, rapidly expanding supernovae, study the interaction of their shock fronts with the circumstellar medium, search for pulsars in their centres and compose the results in a "movie of an exploding star." As a spin-off, we obtain vital information for determining the distance to the host galaxy, which helps to anchor the extragalactic distance scale. We have developed a novel data acquisition system for phase-coherent baseband recording of pulsars to complement our VLBI observations and extend our studies to searches for new millisecond pulsars and their possible companion planets and black holes. Also, we investigate the cosmological jets of energetic particles which emanate from the active centers of so-called superluminal radio galaxies and quasars with speeds that appear to be faster than the speed of light. These studies help us to understand the physics of the immediate environment of these centres which are believed to be supermassive black holes.
Auditory biophysics, especially otoacoustic emissions; Tuvan throat singing; Coupled/nonlinear oscillators; Signal processing in sensory physiology.
I am primarily interested in auditory biophysics, chiefly in the context of how sound is transduced by the ear into neural impulses going to the brain. Remarkably, somehow in the process of being a very sensitive detector, the (healthy) ear generates and subsequently emits sounds that can be detected non-invasively using a sensitive microphone. These sounds, known as otoacoustic emissions (OAEs), reveal many aspects of the inner workings of the ear and also have many translational applications (e.g., clinical audiology). Our lab combines both experimental and theoretical/modeling approaches across a broad comparative framework so to help us better understand OAEs and thereby the key biophysical processes at work that allow us to hear the world around us.
Neutrinos, especially neutrino mixing; Antimatter; Charge-Parity (CP) violation; Particle and radiation detectors.
I study the properties of the neutrino, the least understood of the fundamental particles in our universe, but one that plays a key role in unsolved problems in particle physics and cosmology. Lately, I have been doing so as a member of the T2K experiment in Japan. The consequence of the breakthrough discovery that neutrinos have mass (by the experiments SuperK in Japan and SNO in Canada), contrary to the assumption in the Standard Model of particle physics, gives rise to quantum mechanical mixing among the 3 known neutrinos, encoded in matrix form. One of the goals of T2K was to determine the last unknown parameter in this matrix, theta_13, which is accessible by studying the transformation of muon neutrinos to electron neutrinos (so-called “neutrino oscillations”). At T2K, beams of neutrinos and anti-neutrinos are produced from protons hitting a graphite target. Precise monitoring of this proton beam is essential for understanding the neutrino flux, which is an input parameter for physics studies. I have worked on one of the monitoring devices, an Optical Transition Radiation (OTR) detector, which is critical for measuring the proton beam characteristics in the high radiation environment near the target. The most important outcome of our experiments so far is a measurement that theta_13 is non-zero and relatively large, for which the T2K team was awarded a prestigious prize by La Recherche, a French science magazine. Our results show a way forward to investigate whether neutrino physics holds the key to why our universe is made only of matter, despite matter and anti-matter being produced equally in the Big Bang. We plan to investigate the origin of the matter/antimatter asymmetry by comparing results from data collected with neutrino and anti-neutrino beams.
Applications of Global Navigation Satellite Systems (GNSS), especially to positioning and navigation.
My research interests centre on the use of Global Navigation Satellite Systems (GNSSs), most notably GPS, for a multitude of precise positioning and navigation applications. Specific application areas include crustal deformation monitoring, precise orbit determination, and precise positioning of offshore platforms. This research requires development of positioning algorithms, which include filters, functional models, stochastic models, and prediction models to mitigate physical affects. Recent algorithm research has focused on improving the robustness of precise point positioning, and extending the range of single-baseline, real-time kinematic (RTK) GPS.
Nanophotonics and materials for solar energy and biosensing applications.
Our research focuses on the materials and physical chemistry of nanostructures with potential applications ranging from solar energy conversion to bio-sensing. In particular, we are interested in synthesizing and assembling nanomaterials into 3D and 2D structures via a combination of bottom-up approach and top-down lithographic technique to derive novel optical, electrical, and chemical properties. We employ a wide range of characterization methods and various optical spectroscopies to elucidate the interplay between material properties and functions.
Scientific instrumentation and techniques for missions to planets, moons and asteroids.
I am interested in optical instrumentation, including LiDAR, for planetary mapping and imaging. For example, I led the development of the meteorology instruments aboard the Phoenix lander on Mars, Canada’s first instruments on another planet. Most recently, I have been the lead scientist for the Laser Altimeter (OLA) for the Origins Spectral Interpretation Resource Identification Security Regolith Explorer (OSIRIS-REx). OSIRIS-REx is now on its way to Asteroid 1999RQ36 (Bennu), where it will collect samples and return them to Earth. Besides its value to identifying a sampling site, the OLA data will provide us with new insights into the structure and composition of the surface of one of the most primitive bodies in the solar system. As well, we will be using the data to calibrate observations of asteroids that are made using telescopes on Earth. Separately, I am experimenting with Raman spectroscopy as a tool for measuring constituents of planetary atmospheres. One objective is to develop a rover-based instrument to localize methane, a gas which is a signature of biological activity.
Collider physics; search for long-lived particles; Higgs boson interactions with heavy quarks; neutrino detection and properties; machine learning for high-energy physics; detector development for high-energy physics experiments.
I am an experimental particle physicist, and as such I study the Universe through its tiniest, most fundamental constituents: the elementary particles. I am involved in two international collaborations: the ATLAS Experiment, which is one of the detectors of the Large Hadron Collider (LHC) at CERN, and the Deep Underground Neutrino Experiment, or DUNE, which is a future detector to be hosted by the US laboratory Fermilab near Chicago, Illinois.
The ATLAS Experiment is a five-storey high multi-purpose detector designed to record data from collisions happening at its center. The task for experimental particle physicists is to reconstruct the trajectories and identify the particles produced during these collisions. It enables the observation of new particles or new processes of subatomic physics. In the past, I was involved in searches for Supersymmetry and contributed to the discovery of a rare process: the Higgs boson production in association with a top quark pair (quarks are constituents of protons and neutrons). This complements the LHC’s big success in 2012 discovering the Higgs boson, the particle playing a key role in giving mass to the other elementary constituents of matter. Right now I am searching for “long-lived particles”. Numerous candidate theories attempting to expand our current theoretical framework are predicting particles whose life-times are longer than the ones already discovered. To spot them, we need to rethink algorithms used currently for pattern recognition. I am also active in detector development for high-energy physics. The LHC is preparing to deliver enhanced collisions starting in 2027 (called the High-Luminosity LHC Project). To survive the high rates and radiation levels, some sub-detectors of ATLAS need to be completely rebuilt. I am contributing to the future silicon inner tracker: the ITk. Several sensor units will be assembled and tested by several Canadian institutions.
The Deep Underground Neutrino Experiment (DUNE) is a future leading-edge experiment for neutrino science hosted by Fermilab in the United States. Planned to operate starting in 2026, DUNE will consist of two massive state-of-the-art neutrino detector complexes, one at Fermilab and the second 1300 km away from the first, at the Sanford Underground Research Facility in South Dakota, 1.5 km underground. The Long-Baseline Neutrino Facility (LBNF) will supply intense beams of neutrinos and antineutrinos with energy spectra broader than any other current experiment. DUNE is designed to study how neutrinos change over time (a phenomenon known as oscillations), both for big potential discoveries as well as for precision measurements. An exciting feature of DUNE is its sensitivity to neutrinos coming from the cosmos, especially stellar explosions (supernovae). The Canadian effort on DUNE has just started and the team is growing. As part of the DUNE computing group I am making sure that there is a coherent software framework for data analysis, using my experience on ATLAS. I am also planning to build a test bench for performing feasibility studies on the mechanical/optical parts of the ionization laser device, which will be one of DUNE’s crucial calibration systems.
Active Galactic Nuclei, especially Seyfert galaxies; Cool dwarf stars; Structure of the Milky Way galaxy.
I am interested in the nuclei of galaxies, especially the nature and origin of nuclear activity. Active Galactic Nuclei (AGN) are the centres of some galaxies which emit tremendous amounts of non-stellar radiation. Such radiation is believed to be generated by the accretion of matter -- gas and stars -- onto supermassive black holes. This intense radiation has profound effects on the circumnuclear environment of these galaxies. There are numerous members of the AGN family, including relatively nearby Seyfert galaxies and the more distant quasars. Of particular interest to me is the origin of activity in Seyfert galaxies, especially the role played by the environment in which such galaxies are situated.
I am interested also in aspects of Galactic structure, particularly M dwarf stars. The overwhelming majority of stars in the solar neighbourhood, and indeed in the Milky Way Galaxy itself, are cool, relatively unspectacular stars called late-type (M) dwarfs and subdwarfs. These stars are so faint that they cannot be seen to great distances and are consequently difficult to detect. I am involved in studying how these stars behave within the Milky Way (kinematics), as well as determining their surface temperature and metal abundance using imaging techniques.
Experimental high-energy particle physics; Radio-frequency superconductivity in metallic films.
I am interested in collisions between the most elementary particles available, at the highest possible momentum transfer, and have been involved in the development of instrumentation to do observe them. One focus is the limiting behaviour of niobium and films of niobium and niobium alloys used in superconducting radio-frequency cavities, the aim being to increase the affordable energy of a future linear collider. Previously, I studied high momentum transfer elastic scattering and electron-positron annihilation (ARGUS at DESY). I also participated in the development and construction of the ZEUS calorimeter at DESY, which led to observations that challenged the Standard Model of particle physics.
I have engaged in research into anti-hydrogen atoms with the aim of testing the symmetry of the antimatter and matter worlds, having spent a lot of time at CERN in Geneva in the process. Research has continued through studies of the more conventional helium atom to see if it can provide a platform to precisely evaluate physics theory. I am also interested in the field of curriculum development for undergraduate physics programs, and I particularly like to design modern, relevant and fun experiments for laboratory courses.
Atmospheric emissions; Air quality; Turbulent processes.
I study the emission, deposition, and transport of chemicals, pollutants, aerosols, and particles to and from various sources, including petroleum production facilities, road traffic, forests, and arctic environments. Prior to coming to York, I worked for 5 years as a physical scientist and post-doctoral researcher in the Air Quality department of Environment Canada. Current studies include emissions and mixing of pollutants from highway traffic, emissions from oil sands production facilities, and the interaction of pollutants with forest environments and mixing within the forest canopy. Previously, I have worked on wind-induced transport of sand particles and blowing snow in the Arctic.
Active Galactic Nuclei, especially quasars; Black holes; Gravitational lensing.
When matter spirals into a supermassive black hole at the centre of a galaxy, a kind of friction can heat the matter up until it shines brightly enough to be seen all the way across the universe. We call such objects quasars. I am interested in understanding more clearly the dynamics of gas spiralling around black holes in quasars. That knowledge will improve our ability to infer the physical properties of quasars and their black holes (such as mass and spin) from the details of the light they produce. I am particularly interested in outflows of gas from quasars. Much of the mass spiralling around in a quasar ends up in the black hole, but some of it is flung outwards and is sometimes visible in the spectrum of the quasar. Establishing the connections between those absorption lines and the emission lines seen in most quasars will help us understand how quasars work and how galaxies form. I am also interested in gravitational lensing, which can take a small, faint galaxy and stretch it out into a long, luminous arc. My research is both experimental and theoretical. I do much of my experimental work using online databases from large astronomical surveys, supplementing data as necessary with modern instruments on large telescopes.
Neutrino masses and mixing; Neutrino interactions with nuclei.
My research aims to understand the neutrino, the most abundant particle in the universe that has any mass. Because the neutrino almost never interacts, we know very little about it. However, that same characteristic also means that we can study them by making a beam of neutrinos and shooting them long distances through the earth and studying their composition after they have had time to evolve over time. These measurements can tell us more precisely what the mass differences are between different neutrinos, whether their masses are like the charged fermion mass spectra or the inverse, and whether neutrinos and antineutrinos evolve the same way over time. Because neutrinos have mass, they have a huge impact on galaxy formation in the universe, and if neutrinos and antineutrinos evolve differently, they may be the reason that the universe today is dominated by matter rather than simply being full of light from matter-antimatter annihilations.
The Deep Underground Neutrino Experiment (DUNE) combines an enormous fine-grained neutrino detector with an intense broad-band neutrino beam that has traveled over 1300 km by the time it reaches that detector. DUNE will enable us to test the neutrino oscillation framework at a level of detail and precision that is simply not possible with today’s suite of very capable narrow-band neutrino beam experiments. I will be working on DUNE’s near detector, because the best predictions for what the far detector will see come from an accurate (and tested) description of how neutrinos interact and from extensive measurements from the DUNE Near Detector Complex. My ultimate research plan is to do precision oscillation measurements on DUNE.
However, just as the detector and beamline for DUNE are not yet ready today, the field of neutrino physics as a whole is not yet ready to predict oscillated neutrino event rates over a broad range of energies at the required level of precision. In order to fulfill DUNE's promise of precision we not only have to build the detector and neutrino beamline, but we also have to understand the way neutrinos will interact in that detector. The MINERvA experiment, located at Fermilab, has started writing the book on neutrino interactions and how the nuclear environment affects those interactions. We have collected a huge sample of neutrino and antineutrino interactions on many different nuclei, and are able to shine a much brighter light on neutrinos than ever before. I am currently the co-spokesperson of MINERvA and I am making sure many more neutrino interaction measurements come from MINERvA to best prepare for DUNE.
High-precision laser spectroscopy of atoms; Experimental tests of Quantum Electrodynamics and the Standard Model; Antimatter, especially antihydrogen; Proton radius; Laser cooling and atom trapping.
I employ lasers to make high-precision measurements of atomic properties to test the predictions of Quantum Electrodynamics and the Standard Model of particle physics. Currently, I am studying atomic hydrogen to make a new measurement of the radius of the proton to try to understand the deviant value recently obtained from muonic hydrogen. If the discrepancy is real, it may herald the discovery of a new boson or even gravity in higher dimensions. Also, I am part of a collaboration whose goal is to hold antihydrogen atoms (antimatter versions of the element hydrogen) in a magnetic trap and use them to conduct precise spectroscopic tests of the symmetries and physics of antimatter. Additionally, I am involved in measuring the energies and orbits of helium atoms to provide the most accurate measurement of the "fine structure constant,” the fundamental constant of nature that determines the strength of the electric and magnetic forces between charged objects. The fine structure constant is not only relevant to magnets and electricity, but to how atoms, chemicals, and solid objects are held together.
I study biologically-inspired imaging systems, i.e., electronic camera chips and networks of cameras. My work encompasses distributed sensor systems based on insect and spider eyes, sensor swarms, clouds and "smart dust" modelled on ant colonies and schools of fish, high performance integrated sensor design, on-chip image processing methodologies, semiconductor device modelling and simulation, and radiation tolerant design and manufacturing. Applications include aircraft collision avoidance, space systems, industrial inspection, machine vision, and vision rehabilitation.
Galactic archaeology; Galaxy formation; Data science for astrophysics; Machine learning; Astronomy education and outreach.
My research is "in and above the cloud", combining astrophysics, data science, cloud computing, planetary sciences, optical engineering, telescope operations and telescope observations. My primary astrophysical research focus is galactic archaeology. I have worked with instrumentation and telescopes around the world, and my experience enables me to provide technical leadership for York University's Allan I. Carswell Astronomical Observatory.
Another motivation for me is the promotion of astronomy education and research through public telescope activities and exploration. As a lecturer, trainer, and consultant, I innovate teaching methodologies for interdisciplinary audiences across the sciences as well as for businesses, students and the general public. Also, I am a certified Google Cloud Trainer and Google Cloud Engineer, and I have considerable experience as a trainer and consultant in data science in the private sector.
Molecular mechanisms of biological processes and disease; Cell biology, including stem cells; Drug screening; Biophysical, biomedical, and bioanalytical techniques.
I focus on understanding the molecular mechanisms of diseases, especially cancer, neurodegenerative disorders and immune disorders. To that end, my group and I develop new biophysical and bioanalytical approaches for studying and separating the chemical contents of individual cells, particularly proteins, enzymes, and DNA. We are also interested in understanding the molecular mechanisms that govern the fate of stem cells. Specifically, methods of chemical analysis are combined with advanced techniques in cell biology such as fluorescence image cytometry to study the molecular mechanisms of fundamental biological processes (cell cycle, cell differentiation, and apoptosis).
Wave nature of atoms, especially coherent transient phenomena; Laser cooling and trapping of neutral atoms; Atom interferometry; High-precision measurements of atomic properties; Gravimetry; Laser-based instrumentation.
My research involves studies of coherent transient phenomena in atomic samples such as laser-cooled atoms. Some of this work involves precision measurements using atom interferometry. Applications of this work are related to the development of portable instrumentation. As examples, my students and I have engaged in precision measurements of the atomic recoil frequency, atom interferometric measurements of gravitational acceleration, precise measurements of atomic g factor ratios, numerical simulations of matter wave interference, studies of superfluorescence, measurements of atomic lifetimes and natural line widths, and the development of auto-locked single mode lasers.
Nanosatellite technology development, including micro-propulsion, sensors, and actuators; Remote sensing.
I develop efficient systems and infrastructure for space flight, and direct the Communications and Operations Laboratory. My research interests centre on nanosatellite technology development. Nanosatellites are, in general, spacecraft with a mass less than 10 kg. They have been increasingly recognized as valuable tools for demonstrating new technologies in space as well as an effective means to educate space engineering professionals due to their relatively low cost. My focus has been to develop a series of space technologies that will lead to scientific nanosatellite missions in the near future. Currently, I am investigating several areas including micro- propulsion system design, MEMS-based attitude sensor and actuator design and algorithms to incorporate their low-grade characteristics, and subsystems based upon field-programmable gate arrays. I am a Canadian participant for the QB50 Mission to develop nanosatellites for an Earth Observation experiment.
I have a passion to engage youth from non-science, non-academic backgrounds, and young women in particular, to discover their potential through scientific problem solving and in turn enrich the diversity of ideas and perspectives within the engineering field. To this end, I am a part of many progressive initiatives, including Space Junk, a youth-at-risk workshop with Big Brothers Big Sisters of Toronto, and Go Eng Girl, introducing girls in secondary school to engineering. Also, I initiated and subsequently guided the York University Rover Team, which has won major international awards each year since 2007.
Micro- and nano-structuring of polymer material systems; Bio-based and smart multifunctional materials; Advanced thermal management materials.
My research is focussed on micro- and nano-structuring of polymer material systems, with the emphasis on tailoring and optimizing their multifunctional properties for a wide spectrum of applications (e.g., energy storage and harvesting, sensing and actuation, biomedical devices, thermal management, and environmentally benign packaging). This highly interdisciplinary research area requires integrating the principles and techniques of advanced manufacturing, materials science, fluid mechanics, thermodynamics, and rheological sciences.
Regulation of biological transport; Cellular membranes; Ion channels; Intracellular reponses to stimuli; Electrophysiology; Signal transduction.
I study the regulation of biological transport at all levels of complexity: the whole cell, isolated membranes, and single proteins (that is, ion channels). Transport across cellular membranes defines the intracellular environment under diverse external conditions. Not only does transport control the composition of the intracellular milieu, but it also functions as a mechanism for translating external triggers (light, hormones, etc.) into intracellular responses. The tools I use are electrophysiology (multi-barrelled micropipettes to inject substances into the cell and perform current-voltage analysis, patch-clamping to measure ion channel activity), biochemistry (to characterize transport activity in vitro), and molecular biology (to clone and characterize genes encoding transport proteins). I work with a variety of model systems - algal, fungal, and plant - and focus on transport properties associated with particular transduction processes. For example, I have engaged in research on root hairs to characterize in detail the role of pressure in tip growth and its regulation by signaling cascades and ion transport.
Formation, evolution, and structure of galaxies; Aggregates of galaxies, especially the Local Sheet and analogues; Interstellar matter, especially gaseous nebulae.
I study the formation, evolution, and organization of galaxies large and small, with the objective of elucidating how we came to be. Insights into the mechanisms driving evolution are gained by utilizing gaseous nebulae (planetary nebulae and HII regions) to probe chemical compositions. Surface photometry, particularly at near-infrared wavelengths, is combined with dynamical measurements to seek a unified description of normal galaxies, which facilitates examination of how different kinds of galaxies are related and which ultimately confronts the “nature versus nurture” debate over origins. To refine knowledge about our place in the Cosmic Web, I implement improved methodologies for determining the distances of galaxies. A recent outcome is a precise three-dimensional map of the Local Sheet of galaxies that reveals that the development of our own galaxy, the Milky Way, was influenced by an environment of far greater extent than hitherto recognized. Now, my students and I are finding and studying analogues of the Local Sheet in the greater Universe to learn what attributes of the Local Sheet were most relevant to the realization of the Milky Way as it exists today. Modern simulations of structure formation are utilized as “virtual universes” to guide the interpretation of measurements and to test theoretical foundations. Much of the work on individual galaxies and the structures in which they are embedded also leads to insights about the origin of spin and the nature, localization, and preponderance of dark matter in the Universe. My primary research adversary is interstellar dust, and I have spent a good deal of time uncovering what lies behind it, including two hitherto unknown galaxies in the backyard of the Milky Way as well as the Council of Giants surrounding us.
Space-based remote sensing of Earth's atmosphere, especially stratospheric ozone; Spectroscopic instrumentation and techniques.
My primary research focus is space-based remote sensing of the Earth’s atmosphere. I am especially interested in monitoring atmospheric constituents, such as ozone, and I develop and deploy instrumentation for that purpose. Ozone is a particularly important gas because it shields us from much of the ultraviolet (UV) radiation from the Sun. To monitor UV radiation and the levels of ozone and sulphur dioxide in the atmosphere, I co-invented the Brewer Ozone Spectrophotometer, an instrument that is now deployed on the ground worldwide. To quantify the effect of ozone depletion on shielding and simultaneously apprise the population of the level of danger, I co-developed the UV Index. My students and I continue to develop new methods and techniques for measuring and modeling the chemical composition of our atmosphere.
Experimental tests of the Standard Model of particle physics; Matter/Antimatter asymmetry; Antihydrogen; Physics education.
I am an experimental high-energy particle physicist. Fundamentally, my research is aimed at testing the Standard Model of particle physics. The Standard Model is a fully predictive theory that describes all matter in terms of 12 elementary particles (quarks and leptons) plus the Higgs boson. It also explains interactions between particles as arising from the exchange of other particles. There are two parts to the Standard Model - Quantum Chromodynamics (QCD) which describes the strong/colour interactions between quarks, where gluons carrying the colour charge are exchanged, and the Electroweak Theory which describes electroweak interactions, such as beta decay and electron energy levels in atoms, where photons and the W and Z bosons are exchanged. The goal of experimental particle physics is to use sophisticated particle detectors and very high energy particle accelerators to learn even more about the interactions and properties of the fundamental particles so as to constrain or possibly even cause a complete re-evaluation of the Standard Model.
What particularly interests me is the observation that hardly anything in the Universe today is composed of antimatter, the so-called "Baryon Asymmetry". This is one of the biggest problems in science, because the Standard Model guides us to believe that the Big Bang produced normal matter and antimatter in equal proportions. Since matter and antimatter annihilate upon contact, the preponderance of normal matter today means that there had to be a slight excess of matter over antimatter in the early Universe. To set that up, there must exist an asymmetry somewhere in particle interaction rates. In other words, there must be one or more processes in which the rate in one direction (that of producing normal matter) is slightly higher than the rate in the opposite direction (that of producing antimatter). Thus, much of the work I have done and am doing now has been concerned with studying relationships between normal matter and antimatter.
Presently, I am collaborating on the Antihydrogen Laser Physics Apparatus (ALPHA) at CERN in Geneva, which has made a series of ground-breaking measurements of great significance. ALPHA was undertaken to shed light on the origin of the imbalance between matter and antimatter, the view being that detailed study of the antimatter version of hydrogen (the most prevalent atom in the Universe) might reveal an asymmetry in particle interactions at a deep level. My students and I have led the development of the particle detectors for tracking and locating antihydrogen. The ALPHA team managed to create and trap antihydrogen for the first time and measure its charge (the same as hydrogen, namely zero, within errors). We are in the process of determining whether antihydrogen falls or rises under the force of gravity, and at what rate. Our ultimate objective is to quantify with exquisite precision how well the energy levels of hydrogen and antihydrogen match.
Applied biophotonic and multimodal techniques for diagnostics and therpeutics; Remotely deployable biomedical sensors and devices.
My research centres on harnessing the power of light to study structural-functional changes in humans in the aging processes and consequently develop individualized countermeasures. Biophotonics converges optical and life sciences providing new insights into the mechanisms of pathogenesis, with the aim of developing pre-diagnostic metrics and intelligent phototherapeutic approaches for minimally invasive, real-time interventions. By targeting and tuning desired light-matter interactions, it is possible to study hallmark features of debilitating diseases such as age-related macular degeneration. Through the knowledge acquired, we derive new translational biophysical techniques to deliver powerful biomedical sensor tools, and personalized intelligent radiation therapeutics as well as dosimetry. The MiBAR Lab (Mermut integrated Biophotonics Applied Research Lab) is inspired to create remotely deployable medical devices for global health applications and space life sciences research. We can achieve this with photonic methods compatible with examining human biometrics in unusual and distant environments, such as in space, thereby enabling support of human health in deep space exploratory missions to Mars and beyond.
Planetary volatiles, from ices to atmospheres; Laboratory simulation of planetary bodies; Space mission operations, design, and data analysis; Planetary instrument design and development.
My research interests lie in the planetary sciences, particularly planetary atmospheres and interactions with planetary surfaces. Questions that I address span the solar system, from Earth to Mars to Comets to Ceres to Giant Planets and their icy satellites. For example, how is it that Mars went from being a warm and wet world in the ancient past to the dry and frozen desert world of today? How is it that an icy body like Enceladus can geyser water droplets out into space, and what can that material tell us about the ocean that lies within? In order to find answers to such questions, it is necessary to send spacecraft out to explore and to establish ground-based facilities to interpret returned data.
I am currently supporting Surface Operations on the Mars Science Laboratory Rover (Curiosity) and developing planetary simulation facilities at York University as part of the Planetary Volatile Laboratory. Previously, I have led experimental studies into interactions of volatiles with the Martian surface and polar caps. After my training with the Mars Exploration Rovers, I worked on the Huygens probe to Titan and I also participated in the development of the Surface Stereo Imager for the Phoenix Mars Lander. Also, I have been involved in several conceptual space mission design studies and analogue planetary missions. I have experience modeling scattering in the atmospheres of Earth and of Mars from the ultraviolet into the near infra-red and dynamical modeling of the Martian atmosphere. Recently, my work has led to the first direct detection of fog on Mars, to estimates of the methane content of the martian atmosphere from exogenous sources, and to an understanding of the origin of ridges of ice on the surface of Pluto.
Surface science; Thin films; Preparation and characterization of novel nanomaterials and devices.
My research aims at creating new thin films and nanostructured materials that possess interesting properties that can be used as sensors, solar energy harvesting devices, and electronic components. Ultimately our research goals are to understand the formation of these materials and to relate their structures and morphology to their electrochemical/electronic, catalytic or/and magnetic properties. These studies are critical for implementing thin film and nanostructure technologies because the surface and interface effects often dominate and alter significantly familiar bulk properties in these low dimensionality systems. In search of novel film materials, our work has focussed on the exploration of electro-deposited thin films and nanostructures as well as the use of efficient surface modification methods such as formation of alkanethiol self-assembled monolayers and the hydrosilylation reaction to incorporate relevant functionalities at gold and hydrogen-terminated silicon surfaces, respectively. The latter can be employed as platforms for Matrix Assisted Laser Desorption and Ionization Mass Spectrometry (MALDI MS) analysis. The implementation of surface-sensitive techniques outside vacuum, such as surface X-ray scattering, scanning tunnelling microscopy (STM), or atomic force microscopy (AFM), provides new knowledge on the structure and morphology of these low dimensionality materials. We also use other surface-sensitive methods such as Attenuated Total Reflectance FTIR (ATR FTIR) and X-ray photoelectron spectroscopy (XPS), to characterize these materials.
All of our research projects deal in one way or another with low dimensionality systems and the importance of changes in material properties due to the creation or presence of interfaces. We are currently engaged in several projects: (a) the investigation of the effect that dye functionalities and novel hole transport materials have on solar cell responses in dye-sensitized solar cells; (b) the study of the formation of epitaxial bismuth on conductors and semiconductors; (c) the growth and characterization of ternary alloy semiconductors on nanoporous films; (d) dye adsorption processes at well-defined semiconductor surfaces; (e) surface modifications for the creation of functional surfaces for tissue imaging. Collaboratively, we have engaged in the characterization of systems relevant to biology, such as protein-DNA complex formation for antibiotic resistance, protein nanotube structure and morphology, RNA structure of the tomato bushy stunt virus, and aptamer self-assembly for sensing applications.
Distant galaxies and clusters of galaxies; Formation and evolution of galaxies, especially environmental influences.
Most of my work is on how distant galaxies form and evolve, and how that evolution is related to their larger scale environment. Because light is redshifted by the expansion of the Universe, studies of distant galaxies almost always involve infrared observations. I use sophisticated instrumentation on ground-based and space-based telescopes to conduct multi-wavelength surveys of galaxies and galaxy clusters. In so doing, I am able to constrain star formation rates and galaxy masses as a function of redshift and thereby ascertain how galaxies grow and at what rate.
Nanostructured materials and devices; Nanoscale carbons; Magnetism and magnetic materials; Magnetic recording; Heat transport; Pump-probe techniques.
My research is devoted to heat and electron transport in nanoscale devices, interfaces, materials, and composites, with the aim of improving dissipation and energy efficiency of electronic devices. I am also interested in spectroscopy and optical pump-probe techniques for the characterization of materials and magnetization dynamics near phase transitions. I have experience studying the electronic properties of amorphous semiconductors and novel nanostructured materials such as carbon nanotubes, semiconducting nanowires, and graphene. I have also worked on nanoscale magnetic field sensing devices and energy-assisted magnetic recording technologies.
Space instrumentation; Space test processes; Planetary atmospheres; Radio astronomy.
My research focuses on the development of space-based instrumentation, data analysis techniques and tools, and space test processes to advance planetary research and to improve the performance and reliability of space systems. For example, I am a member of the York University Argus team that is currently operating a pollution monitoring spectrometer in low Earth orbit on the CanX-2 spacecraft. This technology was awarded the Canadian Astronautics and Space Institute Alouette award in 2010. Also, I am the inventor of a novel construction technology for a space elevator which has attracted world-wide interest. In collaboration with Thoth Technology, Inc., I am currently developing a mission to Mars called Northern Light which will explore new regions of the planet. In the process, I have revived Algonquin Park Radio Observatory, and am presently using it for endeavours ranging from spacecraft tracking to very-long-baseline interferometry of pulsars.
Spacecraft dynamics, control and navigation; Formation flying; Active vibration control; Membrane structures; Smart materials and structures; Multi-agent systems; Motion synchronization; Trajectory design and optimization.
I conduct research in spacecraft dynamics, control and navigation. I am particularly interested in cooperative and coordinated control of multiple vehicles, i.e., formation flying. Consequently, I must delve into such areas as active vibration control, smart materials and structures, membrane structures, and motion synchronization. For this purpose, I founded and direct the Spacecraft Dynamics Control and Navigation Laboratory at York University.
Airglow; Aurorae; Atmospheric dynamics and composition; Space instrumentation.
I am interested in the properties of the upper atmosphere, and develop ground- and space-based instruments for conducting measurements. The upper atmosphere, in the region from 80 to 300 km, is where solar energy input first begins to interact with the atmosphere, producing optical emission known as airglow, and aurora. With specialized instrumentation, this emitted light can be used as a diagnostic tool to determine the properties of the atmosphere in this region. With support from NSERC, and the Canadian Space Agency, the Doppler Michelson Interferometer technique was developed for spectral imaging of the atmosphere, yielding images of optical emission rate, temperature and wind. As Principal Investigator for WINDII, the Wind Imaging Interferometer, a joint Canada-France instrument was placed in orbit from 1991 to 2003 on NASA’s Upper Atmosphere Research Satellite and acquired 23 million images of the atmosphere. The data are still providing exciting new information on the dynamics of the upper atmosphere, and how these dynamics influence the distribution of atmospheric species, such as atomic oxygen. Ground-based instruments have been deployed also. For example, an optical observatory was operated at Resolute Bay in Northern Canada to study the polar upper atmosphere. More recently a derivative of WINDII, the Spectral Heterodyne Spectrometer (SHS), has been developed and flown on a high altitude balloon for the measurement of water vapour in the lower atmosphere. Currently, a collaboration with Germany is in place, intended to lead to the launch of a Cubesat satellite carrying an SHS instrument to measure waves in the upper atmosphere.
High-precision laser spectroscopy of atoms; Experimental tests of Quantum Electrodynamics and the Standard Model; Antimatter, especially antihydrogen and positronium; Exotic states of matter; Laser cooling and atom trapping.
I conduct antimatter research with the aim of producing and trapping large numbers of antihydrogen atoms. Comparing the atomic structure of antihydrogen and hydrogen provides a direct comparison between matter and antimatter atoms and a strong test of fundamental symmetries in nature. I am also comparing measurements of positronium, an electron bound to an antielectron, to test the predictions of quantum electrodynamics theory.
Magnetic monopoles and High Electric Charge Objects; detector development and electronics for high-energy physics experiments.
I am an experimental high-energy particle physicist. I am particularly interested in searching for new particles predicted by some theories, such as magnetic monopoles and other long-lived particles. I am also interested in the development of custom electronics for particle searches. I am a member of the ATLAS experiment at the Large Hadron Collider (LHC) at CERN in Geneva, Switzerland, which is the world’s highest energy particle accelerator. As such, I contributed to the 2012 discovery of a new particle believed to be the Higgs boson.
Particle physics is the study of the smallest constituents of matter and the four fundamental forces between them. Our current understanding is that the world is made up of six quarks and six leptons, each apparently grouped into pairs, forming three similar families of matter. Research shows that quarks and leptons do not have any substructure, that is, that they are the fundamental particles. Each of these particles is partnered with an antiparticle with the same mass but the opposite charge. The standard theoretical model of particle physics does not explain why these particles appear in three families, nor does it predict the particle masses. At a cosmological level, we do not understand why the Universe appears to be dominated by matter as opposed to antimatter, nor do we understand the source of the “dark matter” that represents 23% of the matter in the universe. Perhaps there are particles we have yet to discover. To help answer these questions, we need to go back to the Big Bang, when the universe was minute and the temperatures and densities of matter were enormous. Particle accelerators are the tools we use to recreate the conditions of the universe shortly after the Big Bang.
Presently, the York ATLAS group is engaged in a search for magnetic monopoles. All magnetic objects that have ever been observed have a north pole at one end and a south pole at the other end. A magnetic monopole is a particle postulated to carry only a south or a north pole. If a magnetic monopole exists, theory shows that this would explain why there appears to be a fundamental unit of electric charge. This is one of the outstanding mysteries in particle physics today!
We also create custom electronics for particle detection with ATLAS. To that end, I established an electronics test and development laboratory that includes the state of the art equipment necessary for such leading edge electronics projects. For example, we have worked on readout electronics (including firmware development) for the Transition Radiation Tracker in the ATLAS inner detector. We are currently working with a large global team to build a new inner tracking detector. Our industrial partner, Celestica Inc., is doing the wire bonding for the sensor modules in their clean room in their Newmarket facility.
High-precision laser spectroscopy; Laser cooling and atom trapping; Ultracold atoms, Bose-Einstein condensation, and quantum information; Optical lattices; Environmental pollutant monitoring and climate change.
My research interests include a variety of topics in pure and applied physics, such as laser isotope separation, laser cooling, atom trapping, environmental pollutant monitoring, and electromagnetically-induced transparency for use in optical switching. My group has developed a novel way to use acousto/electro-optic modulators to precisely measure frequency shifts. This has been exploited to measure hyperfine splittings, Stark shifts, and polarizabilities of atoms and thereby precisely test predictions of quantum electrodynamics. We were the first in Canada to create a Bose-Einstein condensate in the lab. Work is progressing to study so-called optical lattices of condensates. An array of microtraps to be fabricated using lithography is also being designed. It is of interest for exploring and controlling the interactions between ultracold atoms, such as the transition between a superfluid and a Mott insulator state, and for developing schemes to implement quantum computing.
Atmospheres of Earth and Mars; Applications of lasers to remote sensing (LIDAR); Laboratory simulations of the Martian environment.
I specialize in the study of the atmospheres of Earth and Mars, primarily compositions, climate, and dynamics. To further atmospheric measurements, my group develops and applies laser remote sensing (or LIDAR) instruments for use from the ground, from aircraft, and on Mars. I led the design, testing, and implementation of a LIDAR system on the Phoenix Mars Lander to measure the distribution of dust and clouds. It resulted in the discovery of snow falling from Martian clouds. The next generation of Mars LIDAR will be directed at the surface of Mars to detect the deposition of water. It is being tested in a chamber that simulates the environment on Mars. Scientific progress is already being made with the finding that water can condense out of the atmosphere onto salts on the surface of Mars. To measure ozone, clouds, and aerosols in the Earth’s atmosphere, we have built a LIDAR system for installation on various aircraft. Recently, it was installed on the Polar-5 aircraft (DC-3) and on the Amundsen icebreaker for measurements of the impact of sea ice on air chemistry and ozone. Another recent field campaign has involved installing a LIDAR instrument on a Twin Otter aircraft for measurements of air pollution form the oil sands industry in northern Alberta.
Protein dynamics, structure, and function, including folding; Enzymes; Microfluidics; Time-resolved mass spectrometry; Biophysical Nuclear Magnetic Resonance spectroscopy.
I am interested in protein biophysics, especially dynamics and folding. The tools of structural biology provide beautifully detailed snapshots of the lowest energy (or most readily crystallizable) protein conformation, but offer precious little in the way of dynamic information. Since many aspects of protein function (i.e., substrate binding/release, conformational changes, energy dissipation through bond vibrations, etc.) are inherently dynamic, we are working towards a detailed understanding of the dynamical modes available to proteins that are required to accurately predict their functional characteristics. We use a wide variety of techniques (e.g., microfluidics, time-resolved mass spectrometry, and Nuclear Magnetic Resonance spectroscopy) to facilitate studies of protein conformational dynamics on biologically important millisecond timescales and to characterize the dynamics underlying activity in a number of enzyme systems.
My research interests include computational solid mechanics, dynamics of mechanical systems, and numerical methods and their applications in the aerospace and defence industries. I am particularly interested in space tethers, such as the dynamics and control of tethered spacecraft systems and the application of electrodynamic tether control to the removal of space debris. Other applications include aerial refuelling systems, aerial cable-towed instruments, and underwater cable-towed systems. Additionally I am engaged in developing autonomous space robotics for on-orbit servicing. In support of many of these endeavours, I also study multi-functional composite materials and additive manufacturing in space.