Category Archives: conference

the annual Physics and Astronomy Graduate student conference. This is designed to highlight the research done in the department, as well as provide an opportunity for grads to practice presentation skills.

The 2008 Woolly spider monkey conference Abstracts

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.

The 2008 Woolly spider monkey conference

conference,
When: August 5th, 2008
Where: Ross S137 (Number 30 in York Map)

Attendance is free. We strongly encourage graduate and undergraduates to participate this event.

Organizing Committee:

Alireza Rafiee arafiee@yorku.ca (Chair of the Organizing Committee and Ralph Nicholls Graduate Award)
Brynle Barrett bbarrett@yorku.ca
Carson Mok cmok@yorku.ca

The conference poster

Conference Schedule:

Time Speaker
9:30 Reception
9:50 Opening
10:00 Banafsheh Hashemi Pour
10:20 Xiaoyi Dong (sunne)
10:40 Steven Beals
11:00 Coffee break
11:20 Jesse Rogerson
11:40 Vyacheslav Galymov
12:00 Lunch Provided by PAGE
13:20 Invited Speaker: Dr. Randy Lewis
14:00 Joe Borbely
14:20 Alireza Rafiee
14:40 Yan Sun
15:00 Coffee break
15:20 Carson Mok
15:40 Brynle Barrett
16:00 Invited Speaker: Dr. Tzahi Yavin
16:40 Presenting the Award
17:00 Closing, Election results

Talks are 15+5 minutes and 35+5 minutes long.

About the Woolly Spider Monkey (Other name: Muriquis)

Muriquis have gray, yellow or brown fur; a heavy body; and long limbs. The southern muriqui has a black face, while the northern species’ face is individually mottled. They can weigh up to 15 kg (33 lb). Found in the remnants of the Atlantic coastal forest in Brazil, muriquis are arboreal and diurnal and eat mostly leaves, fruit and flowers. They are able to utilize secondary as well as primary forest. Troops of muriquis have been observed to include from 8 – 43 individuals. They generally contain approximately equal numbers of adult males and adult females. Immature females emigrate from the troop in which they were born in search of a neighboring troop to join. Males remain with their natal troop and reproduce there. There is very little aggression among group members and they are not territorial. A single young is usually born during the dry season (May – September). The range of muriquis may originally have included all Atlantic coastal forests of eastern and southeastern Brazil. Currently, both species are found in highly fragmented subpopulations with low density. The distributions of the two muriqui species do not overlap. B. arachnoides is the southern species, occurring in the states of Sao Paulo and Parana, and B. hypoxanthus is the northern species, in the states of Minas Gerais, Espirito Santo, Rio de Janeiro, and, at least formerly, Bahia. The two species seem to be separated by the Serra da Mantiqueira which extends east-west in the south of Minas Gerais. Reasons for the decline of the muriquis include hunting for food by local natives, the use of infants as pets, and habitat loss due to clearing of forests for agriculture and human habitation. Currently, the major threats are commercial logging in privately owned forests and illegal hunting in federally or state-owned forests .

Source: animalinfo

The 2006 Uakari conference

conference,

When: August 3rd, 2006
Where: Vari Hall C (Number 30)

This is an all physics student conference presented by the Physics and Astronomy Graduate Executive. Students will present 10 minute talks and take a few questions at the end. The goal is to inform each other of our research interestes and persuits and to practice our presentation skills with a friendly audience. All graduate and undergraduates are encouraged to attend.
To present a talk in the conference, please send an email to the president of the PAGE.

Attendance is free. We strongly encourage graduate students to participate this event.

Organizing Committee:

Alireza Rafiee arafiee@yorku.ca
Brynle Barrett bbarrett@yorku.ca
Carson Mok cmok@yorku.ca
Edward Ackad eackad@yorku.ca (Chair of the Organizing Committee)

About the Red Uakari :

The red uakari is a medium-sized monkey weighing about 4 kg (9 lb). The swamp forests that it lives in are periodically flooded. Uakaris are diurnal and are often found in the tops of large trees. Most of the uakari’s diet consists of fruit, but leaves, seeds, insects and small animals are also consumed. Troops of uakaris have been reported to include up to 50 individuals. They usually forage for food in much smaller groups but rejoin the troop to sleep. One young is born every 2 years.
Source: animalinfo

The 2005 Capuchin conference Abstracts

conference,
Abstracts:

Alireza Rafiee

Super Massive Black Hole Mass (SMBH) estimation by Sloan Digital Sky Survey (SDSS)

Using line width of the permitted emission line MgII, and after subtracting all unwanted FeII emission lines, we are going to estimate the mass of the giant black holes which exist at the center of every massive and far away galaxies literally named quasars. The mass of some of these quasars has been reliably estimated by H_beta (in low redshift) and CIV (in high redshift) lines recently. So our job will be a complementary job using mid-range redshift quasars. Catching this purpose, we are using SDSS quasar’s spectra which provides a vast range of quasars spectra.

Ross Baker (1), David McMillan (2), Keith Aldridge (2) and Ian Lumb (1)
Chronology Errors and their effects on the Recovery of Characteristic Time Scales of the Geodynamo from Relative Paleointensity

We model Earth’s magnetic field as a continuing sequence of growths and decays due to a rotating parametric instability (RPI) in the fluid core. We take paleomagnetic intensity as a proxy for the turbulent fluid velocity field, and thus infer properties of the fluid core and geodynamo from estimates of these rates. In this work, we examine the effect of uncertainties in tie point ages on relative paleointensity data from cores of oceanic sediments. The true change in paleomagnetic intensity with time, is distorted by stretching and compressing the observations in time to match known tie points — a process that can be described as passing a paleomagnetic intensity time series though a non-linear filter. We report the results of a simulation that passes a synthetic time series of paleointensity through a filter that distorts the location in time of the data points. Analysis of the filtered series is compared with analysis of the original data to evaluate the effect of temporal distortions on the reliability of recovered growths and decays.

Yiannis Haranas
Modeling the Gravity Field of Mars Using a Lagrangean Approach to Satellite Orbital Dynamics

We attempt to derive and study a model of the Martian gravity field. Our model is based on the study of a satellite in orbit around Mars using a Lagrangean approach to its orbital dynamics. The model includes all possible perturbative forces that the satellite will encounter. From all these forces studied in the course of our work, it was decided by a numerical order calculation that only the following perturbative forces are important in our model because, they produce accelerations comparable or greater than our model’s threshold that was set to be 10 nm/sec 2 on the Martian surface. These forces are: Harmonic correction to Mars’s central potential, solar radiation, relativistic effects, dust dissipation, third body interactions from Mars’s satellite Phobos and the Sun, and finally aerodynamic drag. In the progress of our work the final Lagrangean was derived, and transformed with the help of Keplerian orbital element transformations into a Lagrangean which now describes the motion of the satellite in its orbital coordinate system, and whose all extra terms except the central constitute a force function responsible for the perturbative accelerations exerted on the satellite. Given the force function Lagrange’s equations were derived, a system of six first order differential equations which describe the time rates of change of the satellite’s orbital elements. The solution of this system of equations by appropriate techniques will result in the extraction of the harmonic coefficients C nm and S nm for the gravity field of Mars.

Luchiano Lombardi
Precision Measurement of Hyperfine Splitting in Atomic Helium

The 2 3 p 1 to 2 3 p 2 2.291 GHz fine structure interval of atomic helium is currently being measured. The Ramsey Separated Oscillatory Field technique is currently being used to measure the interval where a 300 Hz uncertainty in the resonance will be achieved. This current measurement along with a subsequent measurement of the 29.6 GHz fine-structure interval will yield a new determination for the fine structure constant.

Jerusha Lederman
The Quasar 3C454.3: An Extragalactic Reference Source for the Gravity Probe B Mission

We have observed the quasar 3C454.3 at 3.6 cm with a VLBI array of 12 or more stations about four times per year since 1997 in support of the NASA-Stanford Gravity Probe B mission (GP-B). GP-B is designed to measure the geodetic and frame-dragging effects predicted by general relativity via the measurement of the precessions of four gyroscopes in a drag-free orbit about the Earth. A “guide star,” HR 8703 (IM Pegasi), serves as the positional reference for the GP-B spacecraft relative to which the precessions are measured. The quasar 3C454.3, in turn, serves as a distant extragalactic source relative to which the motions of HR 8703 can be measured in an inertial frame. Our mission requirement is to determine the proper motion of HR 8703 relative to an inertial frame with standard error.

Dan Comeau
TBA

Eric Rotberg
Measurement of Atomic Lifetime Using Photon Echoes

Scott Beattie
Precision Measurement of Atomic Recoil Using Atom Interferometry

Iain Chan
Measurement of Zeeman Shift of Trapped Rb Atoms

Allan Baytun
Solving the Cosmological Constant Using 6-D Supergravity

Cody Storry
Antihydrogen

The 2005 Capuchin conference

conference,

When: August 25th, 2005
Where: Senate Chambers (9th Floor North Ross)

This is an all physics student conference presented by the Physics and Astronomy Graduate Executive. Students will present 10 minute talks and take a few questions at the end. The goal is to inform each other of our research interestes and persuits and to practice our presentation skills with a friendly audience. All graduate and undergraduates are encouraged to attend.
To present a talk in the conference, please send an email to the president of the PAGE.
Attendance is free. We strongly encourage graduate students to participate this event.

Organizing Committee:

Scott Beattie beattie@yorku.ca (Chair of the Organizing Committee)
Eric Rotberg rotbergt@yorku.ca
Conference Schedule:
Time Speaker
9:45 Reception
10:00 Opening
10:10 Cody Storry
10:30 Allan Bayntun
10:50 Dan Comeau
11:10 Eric Rotberg
11:30 Scott Beattie
11:50 Nathalie Zhou
Lunch Provided by PAGE
1:00 Iain Chan
1:20 Luciano Lombardi
1:40 Ross Baker
2:00 Yiannis Haranas
2:20 Jerusha Lederman
2:40 Alireza Rafiee
3:00 closing
About the Capuchin Monkey :
Life Span: 15 – 20 years
Size: Head and Body = 12 – 22 inches, Tail 12 – 22 inches
Capuchin Monkeys are diurnal and aboreal animals. The origin of the name comes from the appearance of a black skullcap of the monkeys: in French: “capuce”. The capuchin monkey’s hair is very similar to the cowl worn by Franciscan monks. The Capuchin’s hand is similar to the human hand, as with all other primates. The thumbs and big toes of the capuchin monkey are opposable to the other fingers and toes. The head of the animal is round with dark hair at the back. The tail is long, hairy and prehensile, and serves as an anchor or prop when travelling through trees.