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Call for Abstracts: PAGE Graduate Conference 2013

The annual Physics and Astronomy Graduate Conference is coming up!
Date: Friday, October 25, 2013
Time: 10am-5pm
Room: Chemistry 121

Each year, the Executive organize this conference for many purposes. There will also be talks from invited speakers. More information on the PAGE conference can be found here.

Call For Talk Abstracts

Abstracts are now being accepted for those interested in presenting at the PAGE conference. You would be required to generate a 12-15 minute long original presentation, and then participate in a few minutes of questions immediately following your talk. All presenters will be eligible for the Ralph Nicholls Graduate Award in Science Communication (so long as they meet the requirements of the award). Please submit your abstract to page@yorku.ca with the subject PAGE abstract.

A mini poster session will be held during lunch break. Please, feel free to bring the poster that you prepared for your summer conference.

The deadline for abstract submission is Friday, October 4, 2013 (no extensions will be granted).

The PAGE conference promotes the work that we are doing, providing a chance to see what kind of research happens at York. Also, this is a great opportunity to practice you presentation skills in preparation for future conferences, your defence or research evaluation.

Participating in the PAGE conference creates social and professional connections amongst graduate students in our department that may not have been there before.

If you are not convinced of participating in the PAGE conference yet, remember that you can include it in your CV, and the best of all…there will be free food!

Call for Abstracts 2010

Hi all,

The Phyisics and Astronomy Graduate Executive is proud to announce the 2010
PAGE Conference held Thursday October 14, 2010 in Room 121 Chemistry Building,
York University.

All topics related to research in physics, astronomy and atmospheric physics
are welcome. The aim of this issue is to highlight the ongoing research in these
areas, with a particular emphasis on the graduate studies being conducted at
York University. This conference provides an opportunity for students to
present their work in an interdisciplinary environment.
This year, we have our annual student competition for the Ralph Nicholls
award with a monetary value of $100 for the first winner. Prizes will also be
awarded to the second and third place.

Submission guidelines:
Abstracts should be submitted via email to:
vergados [at] yorku [dot] ca
rogerson [at] yorku [dot] ca
or cmok [at] yorku [dot] ca

Abstracts should not exceed 250 words.
Deadline for submission of abstracts: October 5, 2010
Notice of acceptance: October 7, 2010

Guidelines for oral presentations:
Due to the interdisciplinary nature of the conference, the authors should
aim at putting together a non-technical presentation and focus on the following:

15-minute talk
Understandable by a 4th year physics student
General description of the problem

More information and guidelines for the Ralph Nicholls award can be found

Your Physics and Astronomy Graduate Executive,

Mok, Carson (President)
Vergados, Panagiotis (VP, FGS and Departmental representative)
Rogerson, Jesse (VP Finance, GSA representative)

The 2009 PAGE conference Abstracts


Dr. Tom Kirchner (Invited Speaker)

Atomic systems in time-dependent fields:
insights into the fundamental few-body problem
The quantum mechanical few-body problem has challenged physicists ever since the foundations of quantum theory were laid in the 1920s. It might be embarrassing, but even if the mutual forces between the particles are known the solutions of the fundamental equations are not except for a few special cases.

Collisions of atoms and molecules as well as their interactions with laser radiation are well suited to illustrate this worrisome, but also fascinating situation. They will be the topic of my talk. In particular, the role of theory and computations will be discussed and some recent results and insights deduced from them will be presented.

Dr. Veronica Sanz (Invited Speaker)

Having fun at the energy frontier

Many hopes hang on the Large Hadron Collider. Among many conundrums in Particle Physics,the LHC is expected to reply to these questions: what is the origin of mass? which particleis responsible of Dark Matter in the Universe? are there more dimensions than the four we experience everyday? are matter and energy secretly related? In this talk I will outline how the LHC is going to look for those answers during its first years of running.

Steve Beale

Searching for Charge-Parity Violation

The visible universe is composed of almost entirely matter with little or no antimatter. However, matter particles are always produced with an antimatter partner, hence there should be a balance of matter and antimatter. This is the baryon asymmetry problem. To account for this asymmetry, there must be new sources of Charge-Parity (CP) violation. One possible source is matter-antimatter oscillations in the Bs meson system. An asymmetry in the transition rate to/from matter to antimatter would be a clear indication of CP violation. This effect is predicted to be very small in the standard model of particle physics, but may be enhanced by new physics. I will present a measurement of this CP violating charge asymmetry and show how impacts current searches for new physics.

Ioannis Haranas

Satellite motion in a non-singular gravitational potential

The scope of this paper is to study the effects of a non-singular gravitational potential on satellite orbits by deriving the time rates of change of its orbital elements. This is achieved by writing a non-singular potential expression as a function of the orbital elements and then substituting it into the Lagrange planetary equations. In particular, we derive expressions for high and low frequency as well as secular effects and we evaluate them numerically using the low Earth orbiting satellite mission GRACE. We compare the secular effects with the corresponding general relativistic results and we show that the secular effect of the first disturbing term R1 on the perigee shift is equal to

, an effect that most likely will not be easily separated from the corresponding relativistic that is three times greater in magnitude. Finally, the effect of R2 term on the time rates of change of the perigee and mean anomaly for missions like GRACE will not be easily observed since they would also require extremely long orbiting time scales.

Daniel Fitzakerley

Precision Measurement of the 23P2 -to- 23P1 helium Fine Structure Interval

The fine structure constant, α, is a fundamental constant of nature that represents the strength of the coupling interaction between charged particles. Comparisons of experimental values and theoretical predictions of the n=23PJ fine structure intervals of Helium can be used to determine α. The goal of my research is complete a measurement of the 23P2-to-23P1 interval to a precision of 90 Hz (40 ppb). This level of precision is reached by using the Ramsey separated oscillatory field technique wherein the natural linewidth is narrowed using a pair of microwave pulses. This work builds on a 150 ppb measurement completed by our group last year (Phys. Rev. A 79, 060503 (2009): Borbely et al.). If the larger 23P1-to-23P0 interval is measured with the same precision as the smaller 23P2-to-23P1 interval using this technique, the fine structure constant, α, will be determined to a precision of 1.5 ppb.

Maria Georgina Carrillo Ruiz

Field theories on a lattice with many flavours

Interest in non-Abelian lattice gauge theories with many flavours has increased in recent years. These studies aim to address physics that may appear at the energy of the Large Hadron Collider or beyond. In particular, the knowledge of the phase diagram of these theories as a function of the number of colors, flavours and matter representation plays a fundamental role when trying toconstruct viable extensions of the Standard Model. In this talk, we review the lattice formulation of such theories and take SU(2) gauge theory as a casestudy.

Laura Chajet

MHD Modeling of Disk Winds

Broad emission lines (BELs), one of the characteristic features of active galaxy nuclei (AGNs) spectra, are generally single-peaked and blueshifted with respect to the rest frame wavelength. It has been shown (e.g. Murray & Chiang 1997) that these observational results can be explained by assuming that the emission is produced in a wind off the accretion disk surrounding the central black hole. This feature was also explained by Emmering et al. (1992), but considering a magnetocentrifugal wind consisting of clouds. Here we present some preliminary results of the combination of both approaches considering a magnetocentrifugal continuous outflow.

Robert Berthiaume

A Low Cost MOPA System for Laser Spectroscopy

The low cost and robust nature of diode lasers make them suitable for applications in manufacturing, telecommunications, medicine and data handling. Further, they can be configured to have a very narrow linewidth and to be highly tunable, which makes them an attractive tool for spectroscopic research. I will present an overview of a campaign to develop a homebuilt Master Oscillator Powered Amplifier system which includes External Cavity Diode Lasers, Tapered Amplifiers, and Optical Isolators. The master oscillator is built with the same laser diode found in most CD players. The system produces a 600mW single mode beam at 780nm for a tenth of the cost of commercially available systems. Applications include magneto-optical trapping, atom interferometry, and inertial sensing.

Jesse Rogerson

An overview of Giant arcs

Recently, multiple examples of giant arcs created by gravitational lensinghave been discovered. Due to the magnification properties of lensing, these systemsprobe fainter sources than otherwise possible, resulting in extending galaxy/quasarstudies to higher redshifts. Also, due to their high redshift and extended image,these sources provide a unique look at the intergalactic medium. In this talk, Iwill highlight a few examples of giant arcs, and summarize the key conclusions reached by studying these lensing systems.

Yaniv Gura

The Creation of the H−+ Atom

Our goal is to create, detect and study an exotic atom made up of an H- ion along with a positron. Our 1st goal toward eventual spectroscopic measurements of this exotic atom is to create it in a highly excited state and detect it. A bound molecule made up of these constituents (positronium hydride) has been indirectly detected by colliding positrons with methane gas and looking for CH3+ [D. M. Schrader et al, PRL 69, 57]. Our research will produce a positronic atom in a Rydberg state with the positron weakly bound to the H- ion in an atomic configuration rather that H bound to Ps in a molecular state. A beam of H- ions will be directed towards a cloud of positrons that will be waiting in a particular potential well created by a trap consisting of a series of consecutive aluminum and copper hollow cylinders, called electrodes. The H− ions will undergo some process emerging with a positron orbiting at a Rydberg state. Further down the electrode stack the H−+ atom will encounter a strong electric field gradient created by the electrodes. This will strip the positron from the H−+ atom which will allow us to accumulate and detect the stripped positrons. The detection of the positrons in this ionizing potential well will be evidence of the production of H−+ atoms. Tedious optimization has led to a record number of approximately 6.5 million accumulated positrons for this apparatus over 120 seconds and a 100nA beam of H- ions has been produced using a Colutron Ion Gun. Production of this atom will open the door to precise spectroscopic measurements of this atom and may provide greatly improved understanding of the H− ion core.

The 2007 Golden lion tamarin conference Abstracts


Alireza Rafiee

Quasar lifetime and Black Hole Spin Quasars seem to have a limited lifetime
They continuously accrete matter and gain angular momentum but the increase on radiative efficiency of that system remains limited to a physical upper bound. Using that physical barrier, we have estimated an upper limit for quasar lifetime.

Steve Beale

Measuring Bs mixing at the Fermilab Tevatron
Neutral Bs mesons (b-bar s) will spontaneously transform into their anti-particle (and visa versa) by a weak process known as mixing. Measurement of the mixing frequency provides an important constraint on the electroweak coupling of s and d quarks with the top quark. Presently, the only place where this measurement can be made is at the Fermilab Tevatron, a proton-antiproton collider with a center of mass energy of 1.96 TeV. The D0 detector is one of two collider detectors at Fermilab currently working to make this measurement. After a short overview of the Tevatron, the D0 Detector, and general mixing phenomenology, I will present the latest mixing measurement from D0.

Tzahi Yavin

Modelling Markets
In the last quarter of a century or so, the sophistication of the mathematical modeling of financial markets has witnessed a tremendous increase. In this talk I will briefly discuss one of the corner stones in this field, the Black-Scholes model, and how it is used to price options for stocks trading on the stock exchange.

Yan Sun

Density functional study of 13-atom transition-metal clusters and bimetallic A_4B_12 clusters

Min zhang

Global optimization of 13-atom 5d transition metals
We did structural global optimization for six 5d transition metals(Ta-Pt). Two optimization algorithms, Tabu Search in Descriptor Space(TSDS) and Simulated annealing (SA), were used and their performances were compared. Energy evaluation was done with PBE exchange-correlation functional implemented by VASP. Due to complexity of the multiplicities of transition metals, we did calculations with full relaxation of multiplicity. Amazingly, we found none of them had an icosahedral ground state structure. We compared thoroughly our results with previously reported structures. Calculations show that our results are the best. To rule out the difference could be introduced by choice of functional, we did local optimization for our results and structures reported by other researchers with LDA and PW91. The LDA and PW91 functionals give similar results to PBE and confirm that we found the best structures to date for these clusters.

Brynle Barrett

Interferometric Measurement of the Fine Structure Constant using Cold Rubidium
Atoms in an Atomic Fountain One of the most challenging questions in astrophysics today is to establish when and how the universe became (re)ionized. Although it is accepted that the overall process is well understood, and in spite of the observational and theoretical progress that have been made in the last few years, there are still many details that remain controversial and unsolved. At a redshift z ~ 6 we are approaching to the end of Epoch of Reionization, but the number of known quasars and galaxies close to this redshift is still very low, thus the uncertainties are large. To improve our knowledge of that fundamental epoch we need to find more high redshift sources. Here, I will briefly summarize some of the basic ideas on this topic and present the description of the data we are working on and the procedure we have followed.

Edward Ackad

Supercritical Collisions with no intial electrons Colliding two fully ionized
Uranium atoms can lead to pair creation, but solving for a collision with no initial electrons is not commonly done. I will show how it is possible to solve for this system and show results of current work were we can show the enhancement of the positron production due to the decay of supercritical resonance state for collisions with some nuclear sticking.

The 2008 Woolly spider monkey conference Abstracts


Banafsheh Hashemi Pour
A new finite element formulation for 2D nonlinear problem
This paper presents a new 2D FE formulation to treat geometrically nonlinear problems. The new formulation will use nodal coordinates as basic variables to address the limitation suffered by the existing FE methods in dealing with large displacement and rotation, where they solve for nodal displacements. Thus, the errors caused by approximation in kinematic relationship and the accumulated numerical errors arising from the incremental solution procedure of existing methods can be eliminated. 2D formulation is in progress while results in 1D are available.

Xiaoyi Dong (sunne)
SHAPELETS: a new method for the galaxy imaging analysis
Galaxies are most common objects in our universe. Studying galaxies relies on spectroscopic or photometric (imaging) methods. Photometry is much less time-consuming comparing with spectroscopy method, it is ideal to study galaxies classification and variety of galaxies properties at least in statistic sense. Many multi-filter imaging surveys have been done or are being carried on (such as Sloan Digital Sky Survey and CFHT Legacy Survey). Benefits of using multi-filter imaging data are many, for example, galaxies can be classified based on colour-colour diagram. But different filters usually have different PSFs (point spread functions), which causes different imaging have different physical scales. A general method to solve the different PSFs problem is to convolve image of smaller PSFs to match the image of the widest PSF, with the sacrifice of the spatial resolution. SHAPELETS is a new imaging analysis method which is known for studying weak lensing image. We borrow this method to study nearby galaxies. The basic ideal of SHAPELETS is to decompose the image into a series basic functions, which are Gaussian function weighted Hermite polynomial and are orthonormal. The image can be reconstructed using SHAPELETS coefficients with or without a PSF. After a careful test of SHAPELETS, I conclude that SHAPELETS can reconstruct a fair good model to represent the original image, and overall meets the requirement of our work.

Steve Beale
Charge Parity Violation in Bottom Physics

The predominance of matter over antimatter in the universe is know as the baryon asymmetry. Weak processes which violate the charge-parity (CP) symmetry may help explain this phenomenon. These processes are included in the current Standard Model (SM) of particle physics, however they are not predicted to be sufficient to account for the observed asymmetry. Many new models beyond the SM include additional sources of CP violation which may account for this difference. This makes measurement of CP violating parameters an important test for physics beyond the SM.In this talk I will explain the CP symmetry, how it is broken, and how it can be measured using b-meson decays.

Jesse Rogerson
Chandra X-ray Observations of Two Unusual BAL Quasars

Reporting on the results of X-ray observations which do not detect two unusual, luminous FeLoBAL quasars. To block the X-ray emission from these quasars requires high and tightly constrained column densities. To account for the observed characteristics of the quasars requires constrained ionization parameters and density. Based on models using CLOUDY photoionization simulations, the constraints match the observations.

Vyacheslav Galymov
T2K – the next generation long baseline neutrino oscillation experiment

I will provide an overview of the phenomenon of neutrino oscillations, show recent results, and talk about future experiments (mostly T2K).

Invited Speaker: Dr. Randy Lewis
Two-bottomed baryons and exotic light mesons

In nature, all quarks are confined within composite objects. Many such objects have been observed, but some theoretical expectations remain unconfirmed by experiment. What is the status of our understanding in those cases? The vital role of computational theory (i.e. “lattice QCD”) will be discussed through two examples: one involving a pair of heavy quarks and the other with only light quarks.

Joe Borbely
Microwave Measurement of the n=2 Triplet P Fine-Structure of Helium using Ramsey Separated Oscillatory Fields

The Ramsey method of separated oscillatory fields is used to make a very precise microwave measurement of the n=2 triplet P J=1-to-J=2 interval in helium. The excellent signal-to-noise obtained in these measurements allows for extensive studies of systematic effects. The separated-oscillatory-field method allows for subnatural linewidths and provides the ability to vary the lineshape to further study systematic effects. We are in the final stages of completing themeasurement of the 2.29-GHz interval at a precision of less than 500 Hz. Comparison between precise measurements of the n=2 triplet P fine structure and theoretical predictions will allow for a precise determination of the fine-structure constant when the current large discrepancy between experiment and theory is resolved.

Alireza Rafiee
Radiation Screening Effect and Noise factor on Black Hole mass estimates

We study the sensitivity of Super-Massive Black Hole mass estimates to background noise and the quasar’s Eddington ratio. Using a sample of high signal-to-noise ratio quasar spectra from the SDSS DR3, we examine the effect of added background noise on our ability to accurately reconstruct the quasar spectra using Principal Component Analysis, PCA. We study the dispersion in the resulting BH mass estimate as the noise is increased. We also take into account the effect of the radiation screening force on the BH Virial mass estimate. We modify the previously generated scaling relationship which estimates black hole mass.

Yan Sun
Trends in structure and stability of atomic clusters

The properties of atomic cluster vary based on the element and the number of atoms it is made of. By doing a series of unbiased global search with the high-performance technology provided by SHARCNET, we study the structural trends for different groups of atomic clusters and come up with factors that govern cluster structure and stability.

Carson Mok
Measuring gravity with a single state atom interferometer

We describe a method of measuring gravity using a single state atom interferometer. Two standing wave pulses separated by T are applied to a sample of laser cooled rubidium atoms. The atoms evolve into a superposition of momentum states separated by 2hbar k, producing a density grating in the sample that dephases due to the velocity distribution of the sample. The grating that rephases at t= 2T due to the second pulse has a period of lambda/2. This grating is detected by backscattering a readout pulse into a balanced heterodyne detector. The phase of the light is measured against an optical local oscillator. The accumulation of phase as a function of T can be used to find a value for gravity. We have measured g to a precision of 10ppm on a time scale of 20ms by acquiring data over 10 minutes. We discuss improvements to the experiment via increasing time scale, vibration isolating and shielding and correction the RF phase to compensate for mirror vibrations.

Brynle Barrett
Wave Function Simulations of a Matter Wave Interferometer

We present simulations to understand a single-state atom interferometer used to measure the atomic recoil frequency with laser cooled atoms. In the experiment, a standing wave laser is pulsed on at t = 0 which creates a superposition of momentum states. At t = T, a second standing wave pulse diffracts the momentum states again so that a density grating is formed in the vicinity of t = 2T. This grating is associated with the interference of momentum states separated by 2 ħ k. A traveling wave read-out pulse is applied to the sample at this time and the backscattered light from the grating is detected as the echo signal. The amplitude of the echo signal is periodic at the atomic recoil frequency and the duration of the echo envelope is related to the velocity distribution in the sample. Our goal is to model several aspects of the echosignal, both in the short pulse (Raman-Nath) and long pulse (Bragg) regimes, such as the dependence of the echo amplitude on the Rabi frequency, pulse length and spontaneous emission.

Invited Speaker: Dr. Tzahi Yavin
How Strong is the Strong Nuclear Force? In this presentation

I will discuss the strong nuclear force that binds quarks into nucleons and hadrons as described by the theory of quantum chromodynamics (QCD), and how its strength can be determined quite accurately from the decays of the tau lepton into hadrons.