(Change of date)
Thursday 12 December at 1.10pm
Speaker:
Professor Keith Nugent
ARC Federation Fellow, School of Physics,
The University of Melbourne
Title: Coherent X-Ray Optics
Abstract: The rate of increase of the coherent output of x-ray sources exceeds Moore's law. With the planned development of free electron lasers at DESY in Germany and SLAC in the USA, fully coherent x-rays will soon be available. In this talk, I will discuss the development of coherent x-ray optics research with an emphasis on the work being undertaken at the University of Melbourne.
Thursday 5 December at 1.10pm
Speaker:
Mr. E. H. Hirsch
Department of Physics and Mathematical Physics
The University of Adelaide
Title: Anomalous energy distributions of thermionic electrons
Abstract: Experiments are described, which demonstrate energy distributions differing markedly from the Maxwellian distribution normally associated with thermally emitted electrons. This effect appears to be due to electron interaction with space charge oscillations very close to the emitter surface. The experiments shed new light on some previously unexplained observations by early workers in the field of thermionic emission, and a connection with the Langmuir Paradox of plasma physics is briefly discussed.
Friday 25 October at 4.00pm at CSSM, Mathematical Physics seminar. For details see the
Mathematical Physics seminar page.
Thursday 10 October at 1.10pm.
This seminar will now be rescheduled for next year, but see the related
Geology seminar on October 9th.
Speakers: J. R. Prescott and F. M. Williams
Monday 16 September at 1.10pm
Speaker:
A/Prof Lidia Morawska
Director of the Environmental Aerosol Laboratory (EAL)
School of Physical and Chemical Sciences, QUT
(2002 `Women in Physics' lecturer)
Title: Future motor vehicles: will air pollution scientists become obsolete?
Abstract: London Smog and other serious air pollution episodes in the early fifties of the previous century, which were linked to the premature death of thousands of people, turned the eyes of scientists towards the complex field of the physico-chemistry of air pollution. During the past half-century many changes have occurred to the nature, strengths, characteristics and relative contribution of air pollution sources. In urban environments motor vehicle emissions became by far the most significant contributor to gaseous and particle airborne pollutants. In the nineties, new epidemiological evidence pointed to some of the components of vehicle emissions such as very small particles or specific organic compounds, not regulated or even studied until then, to be particularly strongly linked to various health effects. Today, while scientists still vigorously debate what exactly happens in the first few seconds after emission to the nanometre size particles, and clinical doctors continue to look for the mechanisms by which these particles evoke health effects, vehicle manufacturers together with the oil industry introduce new technologies and new fuels, turning motor vehicles into air cleaners. Will the air pollution issue disappear before many scientific and medical unknowns are addressed? The presentation will review the developments in the field of air pollution and human health, motor vehicle impact on these and will discuss the likely future developments in this field.
Thursday 8 August at 1.10pm
Speaker: John O'Connor (University of Newcastle)
Title: AIP - Goals and Directions
Australian Institute of Physics (AIP) president John O'Connor will discuss the future of `Physics in Australia' and in particular the role and goals of the AIP in this matter. There will be time for discussions afterwards.
Honours Physics Colloquia:
Speaker:
Hannah Schunker
Title:
Sunquakes: short time variations of magnetic fields in solar flares have shown
that the solar magnetic field may serve as their source of energy
Abstract:
I will discuss the discovery of "sunquakes" and how my research aids in the
understanding of such phenomena. Preliminary results will be presented from
the high resolution observations obtained with the Michelson Doppler Imager
(MDI) instrument on the SOHO of two large solar flares of 14 July 2000 and 24
November 2000. I show that rapid variations of the magnetic field occurred in
a time scale of a few minutes during the explosion of the flares.
The reversibility/irreversibility
of the magnetic fields of both active regions is a good tool in understanding
how magnetic energy is released in the event of a flare.
Speaker:
Peter Love
Title:
Gravity Waves in the Atmosphere
Abstract:
Waves are a common feature of atmospheric observations. It is therefore
necessary for atmospheric models to be able to account for the various
waveforms observed. A sound understanding of these waves is important
as
they are responsible for the transfer of energy and momentum within the
atmosphere. Internal atmospheric gravity waves, not to be confused with
the gravitational waves predicted by general relativity, are analogous
to waves on the surface of the ocean and can frequently be observed as
stratified parallel bands of cloud. Optical observations of such clouds
provide an opportunity to study the horizontal profile of their
associated waves, a characteristic that is difficult to study using
radar and other well established techniques.
Speaker:
Paul Reich
Title:
Precision Laser Clocks for Photonics
Abstract:
Ultrafast laser pulses can be used as a precise timing device.
However, cavity length fluctuations lead to timing jitter (that is,
irregularity in the pulse rate).
My honours project involves using a Kerr-lens mode-locked laser to
produce the pulses, building a delay line and using an autocorrelator to
correlate the pulses.
I will discuss timing jitter and propose 2 techniques for measuring and
characterising it; one is in the frequency domain and the other is in
the spatial domain which has not been done before.
In addition, precision laser clocks are potential devices for
high-speed optical analog-to-digital converters.
Speaker:
Peggy Kao
Title:
Black hole thermodynamics
Abstract:
Black holes are not really black - they have a temperature and radiate
radiation like thermal objects do. Black holes are also known to have
many properties analogous to those of thermodynamics. In particular, the
four laws of black holes combined with the generalised second law make
up a main framework of the black hole thermodynamics. In these laws, the
Bekenstein-Hawking area entropy relation S = A/4 is the central result.
It has been a long outstanding problem to find a microscopic quantum
description of the thermodynamic properties of black holes, and such a
description was recently provided by string theory for some types of
black holes such as the extreme black hole.
Speaker:
Ben Lasscock
Title:
Scale determination in lattice QCD
Abstract:
I will describe the method of using the static quark potential
to set the scale of lattice simulations.
Speaker:
Magnus Hsu (Supervisor: Prof. Jesper Munch)
Title:
Fiber Bragg Gratings
Abstract:
The fabrication of Fiber Bragg Gratings (FBG) was first accomplished by
K.O. Hill in 1978 at the Canadian Communications
Research Centre. Today FBG has found wide-ranging applications from
increasing the efficiency of Erbium-doped
fiber amplifiers (EDFA) to making narrow-band transmission filters; as well
as stress and temperature sensing implemented in 'smart-structures'.
My Honours thesis involves the fabrication and characterisation of FBG
using the point-by-point, azimuthally
symmetric, mechanical stress relaxation method; induced by a CO2 laser.
In this talk, the physics of FBG are presented, which are solutions of
the coupled-mode equations in waveguide theory.
Following this will be the motivations behind the project, the current
experimental progress and future directions.
Speaker:
Christopher Hunt
Title:
Point Defects in Solids
Abstract:
Crystals are all around us. From the components of modern electronic
circuits to the metals in our buildings and cars, the properties of solids
have profound effects on the way we live our lives. Interestingly, these
properties often depend very little on the elements that make up the
crystal lattice. In many cases, the characteristics of a solid are determined
by the impurities which lie within the host lattice. While planar defects
lead to macroscopic properties such as hardness and rigidity, it is the
point (localised) defects which generate interesting electronic and
photonic properties such as conductivity, colour and luminescence. In this
seminar we discuss the origins and consequences of point defects in
crystals, with particular reference to their role in semiconductors and
the luminescence of quartz.
Speaker:
Paul Davidson
Title:
Viewing Clouds and Cows with an Infrared Camera
Abstract:
Infrared cameras are being installed at the Pierre Auger cosmic
ray observatory in Argentina to monitor cloud cover during operational
periods, providing information important to the reliability of
experimental results. Although infrared cameras of the type being used are
new to commercial markets, their method of operation is well understood
and will be explained using relatively simple physics. The operation of
the camera will be demonstrated, along with a discussion of deficiencies
that have been corrected for. Images demonstrating the ability of the
camera to resolve clouds will be presented; we have also discovered that
cows roaming the Argentinean plains are highly visible in these images.
Speaker:
Mark Cheung
Title:
Supernova Remnants and the Interstellar Medium
Abstract:
At present over two hundred and thirty supernova remnants (SNRs) have
been identified in the Milky Way by astronomers observing at
different wavelengths. Despite their abundance, very little is known
about their distribution within the Galaxy. Radio continuum and
neutral hydrogen observations are particularly useful for studying
the morphologies of SNRs and for measuring distances and other
physical properties such as radius, age and shell temperature. Using
data from the Southern Galactic Plane Survey, we are studying several
remnants. By improving our understanding of individual SNRs and their
collective properties (such as Galactic distribution), we hope to
improve our understanding of the interaction between SNR evolution
and the interstellar medium (including the production of
intragalactic cosmic
rays).
Speaker:
Sarah Clay
Title:
The origin of Cosmic rays and their interaction with our atmosphere
Abstract:
The origin of cosmic rays is still not competely understood,
especially the origin of cosmic rays of the highest energies. Even the
question of a galactic or extragalactic origin is not fully
comprehended.
I will be speaking about the possible arguments for both galactic and
extragalactic sources of cosmic rays and the mechanisms that may be able
to accelerate these microscopic particles to such macroscopic energies.
I will then go on to explain the interaction of these cosmic rays with
our atmosphere and how this interaction makes it possible for us to
detect them.