CERN’s Large Hadron Collider Experiments Bring New Insight Into Matter of the Primordial Universe

Experiments using heavy ions at CERN's Large Hadron Collider (LHC) are advancing understanding of the primordial Universe. 

The ALICE, ATLAS and CMS collaborations have made new measurements of the kind of matter that probably existed in the first instants of the Universe. They will present their latest results at the 2012 Quark Matter conference, which starts August 13 in Washington DC. The new findings are based mainly on the four-week LHC run with lead ions in 2011, during which the experiments collected 20 times more data than in 2010.

Just after the Big Bang, quarks and gluons -- basic building blocks of matter -- were not confined inside composite particles such as protons and neutrons, as they are today. Instead, they moved freely in a state of matter known as 'quark-gluon plasma'. Collisions of lead ions in the LHC, the world's most powerful particle accelerator, recreate for a fleeting moment conditions similar to those of the early Universe. By examining a billion or so of these collisions, the experiments have been able to make more precise measurements of the properties of matter under these extreme conditions.

"The field of heavy-ion physics is crucial for probing the properties of matter in the primordial Universe, one of the key questions of fundamental physics that the LHC and its experiments are designed to address. It illustrates how in addition to the investigation of the recently discovered Higgs-like boson, physicists at the LHC are studying many other important phenomena in both proton-proton and lead-lead collisions," said CERN Director General Rolf Heuer.

At the conference, the ALICE, ATLAS and CMS collaborations will present more refined characterizations of the densest and hottest matter ever studied in the laboratory -- 100,000 times hotter than the interior of the Sun and denser than a neutron star.

ALICE will present a wealth of new results on all aspects of the evolution in both space and time of high-density strongly interacting matter. Important studies deal with "charmed particles," which contain a charm or anti-charm quark. Charm quarks, 100 times heavier than the up and down quarks that form normal matter, are significantly decelerated by their passage through quark-gluon plasma, offering scientists a unique tool to probe its properties. ALICE physicists will report indications that the flow in the plasma is so strong that the heavy charmed particles are dragged along by it. The experiment has also observed indications of a thermalization phenomenon, which involves the recombination of charm and anti-charm quarks to form "charmonium."

"This is only one leading example of the scientific opportunities in reach of the ALICE experiment," said Paolo Giubellino, spokesperson of the ALICE collaboration. "With more data still being analysed and further data-taking scheduled for next February, we are closer than ever to unravelling the properties of the primordial state of the Universe: the quark-gluon plasma."

In the 1980s, the initial dissociation of charmonium was proposed as a direct signature for the formation of quark-gluon plasma, and first experimental indications of this dissociation were reported from fixed-target experiments at CERN's Super Proton Synchrotron in 2000. The much higher energy of the LHC makes it possible for the first time to study similar tightly-bound states of the heavier beauty quarks. The hypothesis was that, depending on their binding energy, some of these states would "melt" in the plasma produced, while others would survive the extreme temperature. The CMS experiment now observes clear signs of the expected sequential suppression of the "quarkonium" (quark-antiquark) states.

"CMS will present important new heavy-ion results not only on quarkonium suppression, but also on bulk properties of the medium and on a variety of studies of jet quenching," said Joseph Incandela, the CMS Spokesperson. "We are entering an exciting new era of high-precision research on strongly interacting matter at the highest energies produced in the laboratory."

The quenching of jets is the phenomenon in which highly energetic sprays of particles break up in the dense quark-gluon plasma, giving scientists detailed information about the density and properties of the produced matter. ATLAS will report new findings on jet quenching, including a high-precision study of how the jets fragment in matter, and on the correlations between jets and electroweak bosons. The results are complementary to other exciting ones, including groundbreaking findings on the flow of the plasma.

"We have entered a new phase in which we not only observe the phenomenon of quark-gluon plasma, but where we can also make high-precision measurements using a variety of probes," said Fabiola Gianotti, the ATLAS spokesperson. "The studies will contribute significantly to our understanding of the early Universe."

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New Bacteria-Resistant Materials Discovered

Using state-of-the-art technology, scientists at The University of Nottingham have discovered a new class of polymers that are resistant to bacterial attachment. These new materials could lead to a significant reduction in hospital infections and medical device failures.

Medical device associated infections can lead to systemic infections or device failure, costing the NHS £1bn a year. Affecting many commonly used devices including urinary and venous catheters -- bacteria form communities known as biofilms. This 'strength in numbers approach' protects them against the bodies' natural defences and antibiotics.

Experts in the Schools of Pharmacy and Molecular Medical Sciences, have shown that when the new materials are applied to the surface of medical devices they repel bacteria and prevent them forming biofilms.

The research was led by Professor Morgan Alexander, and Professor Martyn Davies in the School of Pharmacy and Professor Paul Williams in the School of Molecular Medical Sciences. 

The novel materials had to be found using a new technique

Researchers believed there were new materials that could resist bacteria better but they had to find them. This meant screening thousands of different chemistries and testing their reaction to bacteria -- a challenge which was beyond conventional materials development or any of our current understanding of the interaction of micro-organisms with surfaces.

The discovery has been made with the help of experts from the Massachusetts Institute of Technology (MIT) -- who initially developed the process by which thousands of unique polymers can now be screened simultaneously.

Professor Alexander said: "This is a major scientific breakthrough -- we have discovered a new group of structurally related materials that dramatically reduce the attachment of pathogenic bacteria (Pseudomonas aeruginosa, Staphylococcus aureus and Escherichia coli). We could not have found these materials using the current understanding of bacteria-surface interactions. The technology developed with the help of MIT means that hundreds of materials could be screened simultaneously to reveal new structure-property relationships. In total thousands of materials were investigated using this high throughput materials discovery approach leading to the identification of novel materials resisting bacterial attachment. This could not have been achieved using conventional techniques."

These new materials prevent infection by stopping biofilm formation at the earliest possible stage -- when the bacteria first attempt to attach themselves to the device. In the laboratory experts were able to reduce the numbers of bacteria by up to 96.7per cent -- compared with a commercially available silver containing catheter -- and were effective at resisting bacterial attachment in a mouse implant infection model. By preventing bacterial attachment the body's own immune system can kill the bacteria before they have time to generate biofilms.

Ted Bianco, Director of Technology Transfer at the Wellcome Trust, said: "Infections caused by microbial biofilms binding to the surface of implants often cannot be treated with conventional antibiotics. This makes them a significant challenge in patient care, particularly for those with inserted medical devices like catheters, heart valves and prosthetic joints. The discovery of these new polymers is a great example of how advances in materials science are being exploited in our efforts to improve the performance of critical medical components. Just as materials science gave us the non-stick saucepan, so we look forward to the day of the 'non-stick' medical device."

Bacterial attachment and subsequent biofilm formation are key challenges to the performance of medical devices. This is early stage research but the initial results are very promising. The next stage of this research will be to develop the manufacture of these coatings to enable the performance of these materials to be assessed clinically and the inventors are in early stage discussions with a number of medical device companies.

The results of the £1.3m four year research project supported by a Translation Award from the Wellcome Trust, have been published on August 12, 2012, in the academic journal Nature Biotechnology.

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Spintronics in Computing are Near

Aiming to use electron spins for storing, transporting and processing information, researchers from IBM and scientists at ETH Zurich, a leading European university, have revealed the first-ever direct mapping of the formation of a persistent spin helix in a semiconductor.

Until now, it was unclear whether or not electron spins possessed the capability to preserve the encoded information long enough before rotating. Unveiled in the peer-reviewed journal Nature Physics, scientists from IBM Research and the Solid State Physics Laboratory at ETH Zurich demonstrated that synchronizing electrons extends the spin lifetime of the electron by 30 times to 1.1 nanoseconds -- the same time it takes for an existing 1 GHz processor to cycle.

Today's computing technology encodes and processes data by the electrical charge of electrons. However, this technique is limited as the semiconductor dimensions continue to shrink to the point where the flow of electrons can no longer be controlled. Spintronics could surmount this approaching impasse by harnessing the spin of electrons instead of their charge.

This new understanding in spintronics not only gives scientists unprecedented control over the magnetic movements inside devices but also opens new possibilities for creating more energy efficient electronics.

The Spintronics Waltz

A previously unknown aspect of physics, the scientists observed how electron spins move tens of micrometers in a semiconductor with their orientations synchronously rotating along the path similar to a couple dancing the waltz, the famous Viennese ballroom dance where couples rotate.

Dr. Gian Salis of the Physics of Nanoscale Systems research group at IBM Research -- Zurich explains, "If all couples start with the women facing north, after a while the rotating pairs are oriented in different directions. We can now lock the rotation speed of the dancers to the direction they move. This results in a perfect choreography where all the women in a certain area face the same direction. This control and ability to manipulate and observe the spin is an important step in the development of spin-based transistors that are electrically programmable."

How it Works

IBM scientists used ultra short laser pulses to monitor the evolution of thousands of electron spins that were created simultaneously in a very small spot. Atypically, where such spins would randomly rotate and quickly loose their orientation, for the first time, the scientists could observe how these spins arrange neatly into a regular stripe-like pattern, the so-called persistent spin helix.

The concept of locking the spin rotation was originally proposed in theory back in 2003 and since that time some experiments have even found indications of such locking, but until now it had never been directly observed.

IBM scientists imaged the synchronous 'waltz' of the electron spins by using a time-resolved scanning microscope technique. The synchronization of the electron spin rotation made it possible to observe the spins travel for more than 10 micrometers or one-hundredth of a millimeter, increasing the possibility to use the spin for processing logical operations, both fast and energy-efficiently.

The reason for the synchronous spin motion is a carefully engineered spin-orbit interaction, a physical mechanism that couples the spin with the motion of the electron. The semiconductor material called gallium arsenide (GaAs) was produced by scientists at ETH Zurich who are known as world-experts in growing ultra-clean and atomically precise semiconductor structures. GaAs is a III/V semiconductor commonly used in the manufacture of devices such as integrated circuits, infrared light-emitting diodes and highly efficient solar cells.

Transferring spin electronics from the laboratory to the market still remains a major challenge. Spintronics research takes place at very low temperatures at which electron spins interact minimally with the environment. In the case of this particular research IBM scientists worked at 40 Kelvin (-233 C, -387 F).

This work was financially supported by the Swiss National Science Foundation through National Center of Competence in Research (NCCR) Nanoscale Sciences and NCCR Quantum Science and Technology.

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Urban Sun Corridor 4 Degrees Warmer?

According to the United Nations' 2011 Revision of World Urbanization Prospects, global urban population is expected to gain more than 2.5 billion new inhabitants through 2050.

Such sharp increases in the number of urban dwellers will require considerable conversion of natural to urban landscapes, resulting in newly developing and expanding megapolitan areas. Could climate impacts arising from built environment growth pose additional concerns for urban residents also expected to deal with impacts resulting from global climate change?

In the first study to attempt to quantify the impact of rapidly expanding megapolitan areas on regional climate, a team of researchers from Arizona State University (ASU) and the National Center for Atmospheric Research has established that local maximum summertime warming resulting from projected expansion of the urban Sun Corridor could approach 4 degrees Celsius. This finding establishes that this factor can be as important as warming due to increased levels of greenhouse gases. Their results are reported in the early online edition (Aug. 12) of the journal Nature Climate Change.

Arizona's Sun Corridor is the most rapidly growing megapolitan area in the United States. Nestled in a semi-arid environment, it is composed of four metropolitan areas: Phoenix, Tucson, Prescott and Nogales. With a population projection expected to exceed 9 million people by 2040, the developing Sun Corridor megapolitan provides a unique opportunity to diagnose the influence of large-scale urbanization on climate, and its relation to global climate change.

"We posed a fundamental set of questions in our study, examining the different scenarios of Sun Corridor expansion through mid-century. We asked what are the summertime regional climate implications, and how do these impacts compare to climate change resulting from increased emissions of greenhouse gases," says Matei Georgescu, lead author and assistant professor in the School of Geographical Sciences and Urban Planning in ASU's College of Liberal Arts and Sciences.

The authors utilized projections of Sun Corridor growth by 2050 developed by the Maricopa Association of Governments (MAG), the regional agency for metropolitan Phoenix provides long-range and sustainably oriented planning. Incorporating maximum and minimum growth scenarios into a state-of-the-art regional climate model, the researchers compared these impacts with experiments using an urban representation of modern-day central Arizona. Their conclusions indicate substantial summertime warming.

"The worst case expansion scenario we utilized led to local maximum summer warming of nearly 4 degrees Celsius. In the best case scenario, where Sun Corridor expansion is both more constrained and urban land use density is lower, our results still indicate considerable local warming, up to about 2 degrees Celsius," Georgescu said.

An additional experiment was conducted to examine an adaptation where all of the buildings were topped by highly reflective white or "cool" roofs.

"Incorporating cool roofs alleviated summertime warming substantially, reducing the maximum local warming by about half," Georgescu said. "But, another consequence of such large-scale urbanization and this adaptation approach include effects on the region's hydroclimate."

The cool roofs, like the maximum-growth scenario without this adaptation approach, further reduce evapotranspiration -- water that evaporates from the soil and transpires from plants. Ultimately, comparison of summertime warming resulting from Sun Corridor expansion to greenhouse-gas-induced summertime climate change shows that through mid-century the maximum urbanization scenario leads to greater warming than climate change.

However, pinning precise figures on the relative contribution of each effector is difficult, the authors state.

"The actual contribution of urban warming relative to summertime climate change warming depends critically on the path of urbanization, the conversion of natural to urban landscapes, and the degree to which we continue to emit greenhouse gases," said Alex Mahalov, a co-author and principal investigator of the National Science Foundation grant, "Multiscale Modeling of Urban Atmospheres in a Changing Climate," which supported the research.

"As well as providing insights for sustainable growth of the Sun Corridor and other rapidly expanding megapolitan areas, this research offers one way to quantify and understand the relative impacts of urbanization and global warming,"said Mahalov, the Wilhoit Foundation Dean's Distinguished Professor in ASU's School of Mathematical and Statistical Sciences.

The group conducted their numerical simulations using an "ensemble-based" approach. By modifying their model's initial conditions and repeating their simulations a number of times, they were able to test the robustness of their results. In all, nearly half of a century of simulations were conducted.

"By incorporating differing Sun Corridor growth scenarios into a high performance computing modeling framework with MAG projections, we quantified direct hydroclimatic impacts due to anticipated expansion of the built environment," added Mahalov. Simulations were conducted at ASU's Advanced Computing Center (A2C2).

Georgescu said that one take-home message from this study is that the incorporation of sustainable policies need to extend beyond just greenhouse gas emissions. He also stressed the importance of extending adaptation strategies beyond the focus on mere average temperature.

"Truly sustainable adaptation, from an environmental standpoint, must extend to the entire climate system, including impacts on temperature and hydrology," he said.

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Full Color Images at 100,000 Dots-Per-Inch Resolution, Using Metal-Laced Nano-Structures

Researchers from A*STAR's Institute of Materials Research and Engineering (IMRE) have developed an innovative method for creating sharp, full-spectrum colour images at 100,000 dots per inch (dpi), using metal-laced nanometer-sized structures, without the need for inks or dyes. In comparison, current industrial printers such as inkjet and laserjet printers can only achieve up to 10,000 dpi while research grade methods are able to dispense dyes for only single colour images.

This novel breakthrough allows colouring to be treated not as an inking matter but as a lithographic matter, which can potentially revolutionise the way images are printed and be further developed for use in high-resolution reflective colour displays as well as high density optical data storage.

The inspiration for the research was derived from stained glass, which is traditionally made by mixing tiny fragments of metal into the glass. It was found that nanoparticles from these metal fragments scattered light passing through the glass to give stained glass its colours. Using a similar concept with the help of modern nanotechnology tools, the researchers precisely patterned metal nanostructures, and designed the surface to reflect the light to achieve the colour images.

"The resolution of printed colour images very much depends on the size and spacing between individual 'nanodots' of colour," explained Dr Karthik Kumar, one of the key researchers involved. "The closer the dots are together and because of their small size, the higher the resolution of the image. With the ability to accurately position these extremely small colour dots, we were able to demonstrate the highest theoretical print colour resolution of 100,000 dpi."

"Instead of using different dyes for different colours, we encoded colour information into the size and position of tiny metal disks. These disks then interacted with light through the phenomenon of plasmon resonances," said Dr Joel Yang, the project leader of the research. "The team built a database of colour that corresponded to a specific nanostructure pattern, size and spacing. These nanostructures were then positioned accordingly. Similar to a child's 'colouring-by-numbers' image, the sizes and positions of these nanostructures defined the 'numbers'. But instead of sequentially colouring each area with a different ink, an ultrathin and uniform metal film was deposited across the entire image causing the 'encoded' colours to appear all at once, almost like magic!" added Dr Joel Yang.

The researchers from IMRE had also collaborated with A*STAR's Institute of High Performance Computing (IHPC) to design the pattern using computer simulation and modelling. Dr Ravi Hegde of IHPC said, "The computer simulations were vital in understanding how the structures gave rise to such rich colours. This knowledge is currently being used to predict the behaviour of more complicated nanostructure arrays."

The researchers are currently working with Exploit Technologies Pte Ltd (ETPL), A*STAR's technology transfer arm, to engage potential collaborators and to explore licensing the technology. The research was published online on August 12, 2012 in Nature Nanotechnology.

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