I would be most grateful if you would forward to your graduating
undergraduate classes, suitable candidates, or other colleagues.
The position is open to all nationalities and will commence in Oct 2013.
Thank you
Helen Fraser
___________________________________________________________________________________________________________________________
Fully-Funded PhD Studentship in
“THz Spectroscopy”
Department of Physical Sciences
Open University, Walton Hall, Milton Keynes, MK7 6AA, United Kingdom
**Open to all Nationalities**
Overview:-
The aim of this PhD is to develop a novel THz spectrometer and apply
this state-of the-
art instrument technology to laboratory studies that investigate the synergy
between gas and dust in star-forming environments. The position is a 3.5
year, fulltime
PhD post, starting 1st October 2013 in the in the Department of Physical
Sciences, Open University, United Kingdom
(http://www8.open.ac.uk/cepsar/). The
successful candidate will be expected to spend a total of 18 months on
secondment
at the Rutherford Appleton Laboratories (RAL) during the PhD period.
To apply, please send a 2-page CV, list of publications (if any), a
cover letter clearly
identifying the project to which you are applying, explaining your
enthusiasm and
suitability for the post, to [log in to unmask] by 5pm
(UT) June
21st 2013. Please arrange for two letters of recommendation to be
emailed directly by
your referees to the same address, by the same date. Interviews will be
held on July
9th – 10th 2013 at the OU, Milton Keynes and RAL, Oxfordshire.
Background:-
Since star-formation is intimately linked with galactic evolution,
consuming baryonic
matter, and modifying the elemental metalicity of our universe,
understanding the
star-formation process is a very key challenge of modern astronomy. The
interstellar
medium, in both our own galaxy, and extra-galactic environments, is the
gaseous
and dusty material from which stars from. Prior to the onset of
star-formation, atoms
and molecules tend to 'freeze-out' on the dust surfaces, forming
interstellar ices - the
largest reservoir of molecular material in interstellar regions. As
star-formation
progresses, molecules formed on and in the ice are returned to the gas
phase, via
simple heating, or non-thermal (electron or photon induced) desorption
processes.
This molecular gas then acts as a vital coolant during the collapse
phase of star
formation, as well as providing the ingredient material (along with the
dust and ice)
for planet forming processes. This interplay between the gas and solid
phase is a
crucial feedback mechanism that continuously reflects then influences
the prevailing
physical conditions (such as density temperature or energy balance) as star
formation progresses.
THz Spectroscopy is a vital tool in observational astronomy offering a
handle on such
mechanisms from the sub-mm emission spectra of gases in star-forming
regions.
Modern telescope facilities e.g. Herschel and ALMA have two key
findings; first many
typical coolant gases are actually observed in high-abundance in
energetically
excited states, i.e. rotationally and vibrationally 'hot', suggesting
many more
molecules than previously thought must be non-thermally ejected from
ices; second
that a broad plethora of molecules, from water and methanol (the
'weeds') to complex
organics (the 'flowers') are observed in the spectra, suggesting a rich
chemistry
emerges from both ice desorption and subsequent gas-phase processes
during star
formation. To enable astronomers to elucidate the underpinning gas-dust-ice
interaction mechanisms, and even to fully understand the wealth of
chemical diversity
being revealed, requires detailed laboratory studies of both aspects of
these
processes.
Development and Exploitation of a THz Spectrometer – this PhD:-
The aim of this PhD is to develop, and then exploit an experiment
designed to study
gas-surface interactions, uniquely using the sub-mm spectra as a probe.
A key part of the research activity will require the candidate to
develop and use a
heterodyne spectrometer initially working at the same frequencies as
ALMA band 7
(275 – 373 GHz), but using semiconductor diode technology for the THz mixer
detection element. The radiometer front-end will be initially formed
from existing THz
technologies developed by the RAL Millimetre Wave Technology Group (RAL
MMTG). It will be integrated with a high-speed digital spectrometer and
tested by
using well-known transitions of CO NO and SO2. Experiments will then
follow that
involve NO and H2O ices and ice desorption measurements. This work will be
undertaken jointly between the OU and the RAL MMTG. The frequency range
of the
spectrometer will eventually be extended to encompass 200 - 1000 GHz,
dependent
upon availability of funding. From a scientific perspective this system
can be used to
characterise the sub-mm wave spectra of the 'flower' molecules - and two key
scientific targets to prove the spectrometer sensitivity will be from
the family of PASH
(Sulphur bearing poly-aromatic hydrocarbon molecules) - potential
candidates for the
≈ 600 GHz 'DIB' (Diffuse Interstellar Band) discovered by Herschel.
The spectrometer will then be installed at the OU, where interstellar
ice analogues
will be grown in situ under low vacuum and temperature conditions
emulating the
ISM. Ice desorption, stimulated by thermal heating, low energy electrons
(50 - 500
eV) and photons will all be used sequentially to liberate molecules from
the surface,
and FT sub-mm emission spectroscopy of the liberated gases measured
against a
cold background plate. The experiments will probe ro-vibrational
excitation, orthopara
distributions (in NH3 and H2O) and yields on non-neutral species, such as
radicals (OH, NO) and water clusters, liberated from the surface.
PhD Organisation
The PhD will be jointly supervised by Dr Helen Jane Fraser (OU) and Prof
Brian
Ellison (OU / RAL Space). Initially the student will be expected to work
at RAL Space,
developing the sub-mm spectrometer, sources and detectors within the
sub-mm and
mm astronomy group, utilising existing technology from ALMA and
Earth-Observation
instruments. The student will then relocate to the OU - where the ice
chamber will be
constructed and tested in parallel with the spectrometer. Finally the
opportunity exists
to exploit the spectrometer for future scientific astronomical and earth
observation
missions, or industrial monitoring applications; these applications will
be explored
between RAL and the OU in the final year of the project. RAL and the OU
are within
a few hours’ drive of each other, so throughout the PhD day visits are
viable from
both supervisors and the student throughout the studentship, likely
monthly. Both
sites are commutable from Oxford, Milton Keynes and other nearby towns.
The studentship will cover fees and a maintenance grant of £13,726.00
per annum,
and the PhD will be overseen and awarded by the OU. The position is open to
students of any nationality.
Candidate Requirements:-
Candidates for this PhD should have a Bachelors, or preferably Master’s
degree,
(minimum 2:1 or 1st equivalent) in a suitable subject area, i.e.
Physics, Electrical
Engineering or Chemistry (with a strong emphasis on Physical Chemistry). The
candidate should have a strong background in experimental laboratory work,
particularly RF engineering or microwave and sub-mm spectroscopy, and / or
instrument design and development, and experience of instrumental
programming is
preferable, in languages such as Labview. The research will involve
using vacuum
equipment, RF technology, cryogenics, computing, and quantum mechanical
analysis of spectral features. Some experience of one or all of these
areas is
therefore advisable. An interest in the astronomical applications of the
project is
advisable.
To apply, please send a 2-page CV, list of publications (if any), a
cover letter clearly
identifying the project to which you are applying, explaining your
enthusiasm and
suitability for the post, to [log in to unmask] by 5pm
(UT) June
21st 2013. Please arrange for two letters of recommendation to be
emailed directly by
your referees to the same address, by the same date. Interviews will be
held on July
9th – 10th 2013 at the OU, Milton Keynes and RAL, Oxfordshire.
For additional information or queries please contact:-
[log in to unmask] 0044 1908 322 921
--
Dr Helen Jane Fraser
Astronomy Division
CEPSAR, Department of Physical Sciences
The Open University
Walton Hall, Milton Keynes
MK7 6AA, UK
direct dial = + 44 1908 332 921
--
The Open University is incorporated by Royal Charter (RC 000391), an exempt charity in England & Wales and a charity registered in Scotland (SC 038302).
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