Neutrinos are fundamental particles which are created in radioactive decays, in fusion processes in stars, such as our Sun, and in cosmic ray interactions with the Earth’s atmosphere. Even though neutrinos are very abundant in nature and billions pass through our bodies each second, their very weak interaction make observation challenging.
Similar to other fundamental particle of the Standard Model, neutrinos come in three flavours: electron-, muon- and tau-neutrino.
The 2015 Nobel prize for Physics was jointly awarded to Prof. Arthur McDonald of the Sudbury Neutrino Observatory (SNO) in Canada and Professor Takaaki Kajita of the Super-Kamiokande (Super-K) collaboration in Japan. The experimental teams led by the laureates showed that neutrinos can switch (or oscillate) between the different flavours. This important observation implies that neutrinos have a small but non-zero mass.
The SNO experiment focused on studying neutrinos produced in our Sun. Previous measurements, for which Ray Davies was awarded the 2002 Nobel prize, indicated that there was a deficit in the electron-neutrinos produced compared to expectations from solar models. The measurements from SNO solve this discrepancy by showing that the electron neutrinos produced were oscillating into muon- or tau-neutrinos. The Super-K experiment is a large underground detector in Japan, consisting of a cylindrical stainless steel tank that is 41 m tall and 39 m in diameter holding 50,000 tons of ultra-pure water. It’s large size makes it ideal to detect and study neutrinos produced in the atmosphere and the experiment demonstrated the oscillation phenomenon applies also to muon-neutrinos, changing flavour into tau-neutrinos.
'The award of the Nobel prize for neutrino physics is fantastic news and well deserved. The fact that neutrinos oscillate and have mass was totally unexpected’.
Dr Greig Cowan, University of Edinburgh
Scientists at the University of Edinburgh, including Greig, have recently joined the planned successor to the Super-K experiment, called Hyper-K. Hyper-K is also an underground detector located in Japan, filled with 1 million metric tons of ultrapure water, a volume approximately 20 times larger than that of Super-K. Start of science operation is foreseen from around 2025.
The behaviour of neutrinos could well surprise us in the future, in particular Hyper-K aims to study with unprecedented accuracy the differences in the switching properties for neutrinos and their anti-matter counterpart. During the Big Bang equal amounts of matter and anti-matter should have been produced. However, our Universe we see today is dominated by matter.
As Dr Cowan explained 'There must be new yet unknown physics processes that distinguish matter and anti-matter. One possibility is that neutrino oscillations are not the same for neutrinos and anti-neutrinos, which could help resolve the puzzle of the matter asymmetry of the Universe. If this is the case we will pin this down with Hyper-K in the coming years. The next years are going to be very exciting times for neutrino physics.'
The Scottish Universities Physics Alliance (SUPA) is offering PhD studentships for outstanding students from anywhere in the world.
These prestigious and competitive awards are intended to attract excellent students to study for a PhD in Scotland. SUPA opens a single front door into Physics PhDs in Scotland. When you apply for a SUPA Prize PhD Studentship you will also be considered for all other funded places available in physics departments in Scotland.
Major themes pursued by researchers in SUPA are:
- Astronomy and Space Physics
- Condensed Matter and Materials Physics
- Energy
- Particle Physics
- Photonics
- Physics and Life Sciences
- Nuclear and Plasma Physics
SUPA Prize Students are registered for a PhD in physics at one of the participating universities:
- Aberdeen
- Dundee
- Edinburgh
- Glasgow
- Heriot Watt
- St Andrews
- Strathclyde
- University of the West of Scotland
An excellent training environment will be provided by the SUPA Graduate School, giving candidates access to a wide range of courses across Scotland.
How to Apply
Applications should be made using the online application form available at: http://apply.supa.ac.uk/
Instructions for completing the form are given in our Application Guide.
Applications MUST be submitted by 23:59 GMT on Sunday 31st January 2016.
References MUST be uploaded by 23:59 GMT on Sunday 7th February 2016.
You will be informed of the result of your application by each institution. You must also apply to your chosen SUPA university to undertake a PhD and are obliged to meet the minimum requirements of that institution.
The soft matter physics group part of the Institute for Condensed Matter and Complex Systems took part in Doors Open Day, Edinburgh on 26th of September in the James Clerk Maxwell Building.
Eighteen researchers from the group showed demonstration experiments and guided visitors around the group’s laboratories. During the day 340 visitors made slime, punched corn starch and learned about the physics of bacteria. Researchers also chatted to lots of people visiting the department as part of the UCAS open day.
The demonstration experiments highlighted properties of non-Newtonian fluids whilst an interactive exhibition with microscopes and computer simulations allowed visitors to explore the groups’ research into active matter. In the labs visitors were able to see the rheometers (mechanical testing devices) and microscopes used to study these complex systems.
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The School of Physics & Astronomy had a particularly strong line-up of speakers in this year's Orkney Science Festival, contributing to its outstanding public engagement record.
Peter Higgs' appearance attracted great interest and as expected "Peter Higgs in Conversation" at the Kirkwall Arts Theatre was a complete sell-out. His conversations with fellow particle physicist and science writer Frank Close were followed by the presentation "From Maxwell to Higgs - and Beyond?" by Alan Walker and Victoria Martin. Clive Greated's presentation "Sounds Around Us" at Pier Arts Centre in Stromness was also a sell-out.
The Particle Physics For Scottish Schools Exhibition (PP4SS) was present throughout the Festival, reaching a total audience of over 2000.
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Physical Review Letters has published a paper on turbulence by PhD student Moritz Linkmann and Alexander Morozov, both of the School of Physics & Astronomy.
Paper summary
Chaotic flows of liquids or gases far away from any boundary, like many atmospheric and oceanic flows, are often viewed by scientists as real-life realisations of the so-called forced isotropic turbulence - a classical idealised description of turbulent motion that dates back to the beginning of the 20th century. In this framework turbulence is driven by a vigorous large-scale stirring and was thought to be featureless at smaller scales: if one would look at the flow through a magnifying glass, one should see the same picture independent of the degree of magnification. This is in contrast with turbulence between boundaries, like flow in a pipe, where recent research showed that the flow is organised by spatially regular, unstable structures.
Surprisingly, computer simulations performed in the Letter suggest that forced isotropic turbulence is not featureless and is much more similar to wall-bounded flows than was thought previously. We demonstrate that at moderate Reynolds number isotropic turbulence is always metastable and the probability of its sudden disappearance obeys an exponential law, previously found in experiments and simulations on pipe flows.
The similarities between the two systems suggest a universal scenario in which turbulence is always organized around unstable, spatially regular structures.
"It was very interesting to find that isotropic turbulence, which is an idealised system that allows the study of fundamental turbulent dynamics without having to consider external influences such as the geometry (and walls) of a container, is connected to real-world flows such as flow through a pipe." Moritz Linkmann, PhD student, School of Physics & Astronomy
Below, Moritz Linkmann explains the research behind the paper.
Dynamical systems and the transition to turbulence in parallel shear flows
In parallel wall-bounded shear flows (such as flow through a pipe or counter-rotating cylinders) the transition to turbulence does not occur due to a linear instability of the laminar profile. The state space of the system, where each point corresponds to a flow state, is organised by a complicated collection of unstable flow states and the linearly stable laminar profile. Turbulence is then characterised as the system revolving around these unstable flow states (so-called `exact coherent structures'). The important point is that the laminar profile and the turbulent states remain dynamically connected and a sudden `escape' from the turbulent region of state space can occur. Localised turbulence in a flow can therefore suddenly relaminarise and this has been observed in many experiments of parallel shear flows. This relaminarisation is a memoryless process, that is, it does not depend on the amount of time the system has spent in the turbulent region of the state space. A characteristic timescale can be associated with this process which increases with Reynolds number as a double exponential. This implies that there is always a finite probability of relaminarisation, even at high Reynolds numbers: Localised turbulence in wall-bounded shear flows is transient.
The transition to sustained turbulence then occurs due to a competing process,that is the splitting of a locally turbulent region into two. This process also has a characteristic timescale which now decreases with Reynolds number as a double exponential. The critical Reynolds number for sustained turbulence is then defined at the point where the two timescales are equal.
Collapse of isotropic turbulence
Isotropic turbulence and a parallel wall-bounded shear flow are a priori very different systems, isotropic turbulence being a simplified system studied in order to establish fundamental properties of turbulent flows. It is often thought of as high Reynolds number limit of wall-bounded flows, where the walls have negligible influence on the turbulent dynamics. It is traditionally studied in statistical terms and in numerical simulations, where the decay of turbulence due to viscous dissipation is balanced by an external energy input at the large scales. The emphasis in the simulations is usually on achieving high Reynolds numbers. The dynamics of forced isotropic turbulence has been thought to be as simpler than that of parallel shear flows. In particular, isotropic turbulence is not expected to show transitional behaviour and nothing is known about its phase space structure.
In this study we investigated the same system at low Reynolds numbers and observe a sudden collapse of turbulence in favour of a large-scale ordered flow. This can be seen in the figures, which show streamlines of the flow before and after the collapse of turbulence. A transition from a 'disordered' to an 'ordered' flow is clearly visible. This collapse of turbulence happens despite the continuous stirring of the flow at the large scales and had been observed in a previous study already. Our analysis, which is new in the sense that it is the first time that a dynamical systems approach has been applied to isotropic turbulence, now shows that this collapse has very similar features to relaminarisation events in pipe flow: It is a memoryless process with a characteristic timescale that increases with Reynolds number in much the same way as in wall-bounded shear flows. Furthermore, the base flow appears to be linearly stable. This shows that isotropic turbulence at low Reynolds numbers is transient and it suggests that the phase space dynamics of wall-bounded shear flows and isotropic turbulence may be very similar.
Outlook: the universality class of the transition to turbulence
Recent research suggests that the transition to turbulence in parallel shear flows constitutes a second-order nonequilibrium phase transition belonging to the Directed Percolation universality class. That is, the transition to turbulence in these flows behaves like, for example, the spread of diseases or wildfires. The similarities between relaminarisation in pipe flow and the collapse of isotropic turbulence reported here suggest that this behaviour may in fact be a universal feature of turbulence and plans are under way to investigate this further.
This work has made use of the resources provided by the Edinburgh Compute and Data Facility (http://www.ecdf.ed.ac.uk). Moritz Linkmann and Alexander Morozov acknowledge support from the UK Engineering and Physical Sciences Research Council (EP/K503034/1 and EP/I004262/1).
Reference: M. Linkmann and A. Morozov, Sudden Relaminarization and Lifetimes in Forced Isotropic Turbulence, Phys. Rev. Lett. 115, 134502
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The School of Physics and Astronomy is opening its doors at the end of September.
Coordinated by the Cockburn Association, Doors Open Day is an annual opportunity for the public to visit buildings and institutions across the city that are not available during the rest of the year.
Take a guided tour of the Institute for Condensed Matter and Complex Systems (ICMCS) and go behind the scenes of soft matter research on Saturday 26 September at the James Clerk Maxwell Building on the King’s Building campus. You will have the opportunity to experiment with a variety of hands-on activities alongside staff and students, including having the chance to make and take away your own slime!
On Saturday 26 & Sunday 27 September, you will have the chance to talk to astronomers from the Institute for Astronomy about their work on galaxy evolution, planet formation and computer simulations of the Universe. There will be hands-on craft activities including making your own origami brown dwarf and the chance to try your hand at characterising light curves from stars to spot exoplanets. Relax on the sofa in the astronomers’ corner while discussing the big questions of the Universe and get an insight into the working life of an observatory. These events take place at the Royal Observatory Edinburgh.
Childhood memories of sticky hands from melting ice cream cones could soon become obsolete, thanks to a new food ingredient.
Scientists have discovered a naturally occurring protein that can be used to create ice cream that is more resistant to melting than conventional products. The protein binds together the air, fat and water in ice cream, creating a super-smooth consistency.
The new ingredient could enable ice creams to keep frozen for longer in hot weather. It could also prevent gritty ice crystals from forming, ensuring a fine, smooth texture like those of luxury ice creams. The development could allow products to be manufactured with lower levels of saturated fat – and fewer calories – than at present.
Researchers at the Universities of Edinburgh and Dundee developed a method of producing the new protein – which occurs naturally in some foods – in friendly bacteria. They estimate that ice cream made with the ingredient could be available within three to five years.
The protein works by adhering to fat droplets and air bubbles, making them more stable in a mixture. Using the ingredient could offer significant advantages for ice cream makers. It can be processed without loss of performance, and can be produced from sustainable raw materials.
Manufacturers could also benefit from a reduced need to deep freeze their product, as the ingredient would keep ice cream frozen for longer. The supply chain would also be eased by a reduced need to keep the product very cold throughout delivery and merchandising.
The protein, known as BslA, was developed with support from the Engineering and Physical Sciences Research Council and the Biotechnology and Biological Sciences Research Council.
Professor Cait MacPhee, of the University of Edinburgh’s School of Physics and Astronomy, who led the project, said: “We’re excited by the potential this new ingredient has for improving ice cream, both for consumers and for manufacturers.”
Dr Nicola Stanley-Wall, of the University of Dundee, said: “It has been fun working on the applied use of a protein that was initially identified due to its practical purpose in bacteria.”
Computer models of developing cancers reveal how tiny movements of cells can quickly transform the makeup of a tumour.
The models reinforce laboratory studies of how tumours evolve and spread, and why patients can respond well to therapy, only to relapse later.
Cell changes
Researchers used mathematical algorithms to create three-dimensional simulations of cancers developing over time. They studied how tumours begin with one rogue cell which multiplies to become a malignant mass containing many billions of cells.
Their models took into account changes that occur in cancerous cells as they move within the landscape of a tumour, and as they replicate or die. They also considered genetic variation, which makes some cells more suited to the environment of a tumour than others.
Transforming tumours
They found that movement and turnover of cells in a tumour allows those that are well suited to the environment to flourish. Any one of these can take over an existing tumour, replacing the original mass with new cells quickly - often within several months. This helps explain why tumours are comprised mostly of one type of cell, whereas healthy tissue tends to be made up of a mixture of cell types.
Therapy resistance
However, this mechanism does not entirely mix the cells inside the tumour, the team says. This can lead to parts of the tumour becoming immune to certain drugs, which enables them to resist chemotherapy treatment. Those cells that are not killed off by treatment can quickly flourish and repopulate the tumour as it regrows.
Researchers say treatments that target small movements of cancerous cells could help to slow progress of the disease.
Joint study
The study, a collaboration between the University of Edinburgh, Harvard University and Johns Hopkins University, is published in the journal Nature. The research was supported by the Leverhulme Trust and The Royal Society of Edinburgh.
"Computer modelling of cancer enables us to gain valuable insight into how this complex disease develops over time and in three dimensions.” Dr Bartlomiej Waclaw, School of Physics and Astronomy
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A new astrobiology textbook and complementary lectures written by the School's Prof Charles Cockell and published by Wiley-Blackwell will encourage other universities to teach this complex subject.
Astrobiology is an interdisciplinary field that asks profound scientific questions. How did life originate on the Earth? How has life persisted on the Earth for over three billion years? Is there life elsewhere in the Universe? What is the future of life on Earth?
Astrobiology: Understanding Life in the Universe is an introductory text which explores the structure of living things, the formation of the elements for life in the Universe, the biological and geological history of the Earth and the habitability of other planets in our own Solar System and beyond. The book is designed to convey some of the major conceptual foundations of astrobiology that cut across a diversity of traditional fields including chemistry, biology, geosciences, physics and astronomy. It can be used to complement existing courses in these fields or as a stand-alone text for astrobiology courses. The text book also comes with 21 full lectures on astrobiology, allowing anyone to set up a complete astrobiology course.
"The major stumbling block to new astrobiology courses so far has been the difficulty of gathering all the required information for a very diverse subject and making lectures that match an existing textbook. This has been a barrier to new astrobiology courses around the world. This textbook and accompanying lectures now solves this problem." Charles Cockell, Professor of Astrobiology, School of Physics & Astronomy
The intended audience includes undergraduates studying for degrees in earth or life sciences, physics, astronomy and related disciplines, as well as anyone with an interest in grasping some of the major concepts and ideas in astrobiology.
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A new video traces the development of the School of Physics & Astronomy and reflects on the achievements of some of its students and staff.
The film opens in the house where James Clerk Maxwell was born, with Sir David Wallace describing the early days when he was a student at Edinburgh. Professors Stuart Pawley, Alan Shotter and Murray Campbell then reflect on early achievements at Edinburgh in high-performance computing, nuclear physics and applied physics, followed by Prof. Peter Brand who describes the symbiosis of Physics with Astronomy and how research methods have changed over the generations.
Finally Nobel Laureate Prof. Peter Higgs talks about how he was inspired to work in the area of theoretical physics, and the relationship between the theoretician and experimentalist.
