CUORE experiment gets to the 'heart' of the anti-matter

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CUORE-0 is the first step toward the realization of the Cryogenic Underground Observatory for Rare Events (CUORE) located at the underground Laboratori Nazionali del Gran Sasso, in Italy. (The word 'cuore' means heart in Italian.)

The project, funded at LLNL by the Department of Energy's Office of Science and LDRD, involves searching for an extremely rare radioactive process known as neutrinoless double-beta decay. The experiment brings together more than 100 U.S. and European scientists to build a 1-ton detector array.

Lawrence Livermore along with Lawrence Berkeley national laboratories, and several U.S. universities, including the University of California at Berkeley, University of California at Los Angeles and CalPoly, are involved in the CUORE collaboration. Pedretti had done some work previously on the CUORE project in Italy, and then was approached to come to the United States to similar work here. As experimental coordinator, she will play a leadership role in the CUORE-0 commissioning, operation and overall scientific program.

This double beta decay experiment is designed primarily to search for the neutrinoless double decay of Tellurium-130 , one of a few isotopes with high isotopic abundance that allows high sensitivy. It will use a bolometric technique to measure the temperature changes produced in large crystals of tellurium dioxide when radiation is absorbed.

The CUORE detector will contain an array of nearly 1,000 tellurium dioxide crystals, each a 5-centimeter cube. The crystals will be cooled to 0.01 degrees above absolute zero. At this temperature, each crystal's heat capacity is small enough that the energy from a single radioactive decay within the crystal will be detected. Sensitive thermometers outside the crystals will indicate a change in temperature, which will then be used to determine the decay energy.

According to Pedretti, who has conducted prior research in detection, the CUORE project explores a new area of physics --- the search for neutrinoless double beta decay, a process which only recently has become a highlight of nuclear physics.

"When we look at fundamentals of physics, we use a physics model called the 'Standard Model (SM)'. But we know it is not perfect,"Pedretti said."Many things are not completely clear. New models and ideas have been proposed to answer the questions left open by the SM. To understand which of these models explains reality, we have to compare their predictions with reality, in other words with the results coming from experiments that aim to test that areas of physics where the SM can fail. Here, the neutrino plays a fundamental role, and in particular some of the properties of this particle are crucial."

In standard double-beta decay, two neutrons in a nucleus are converted to two protons, emitting two beta particles and two neutrinos that share the energy generated from the decay.

In neutrinoless decay, the neutrinos annihilate each other instead of being emitted, and the full energy - a little over 2 megaelectronvolt s- is carried away by the beta particles. This decay can only occur if a neutrino and its antimatter, the antineutrino, are the same particle.

Pedretti said that the neutrinoless double-beta decay experiments at CUORE could reveal unique properties of neutrinos that no other experiments have demonstrated thus far.

Life in the United States

Pedretti who hails from Piacenza in northern Italy, received her undergraduate degree in nuclear physics from the University of Milan in 2000, and a Ph.D. in physics from the University of Insubria in 2004.

As a young student, she switched her concentration from business to math and physics. Coming from Italy, it is no wonder that her hero is Italian physicist and Nobel Prize winner Enrico Fermi.

"A genius,"she says of Fermi, but adds that he was much more -- he influenced and schooled many young scientists."He collaborated with many students and in doing so, helped them to become leaders in their own fields of science."

This is the first time Pedretti has lived in the United States, and although she previously would have been content to remain in Italy where she was established within the European scientific community, she has found many more opportunities to pursue at LLNL and has gained a lot of confidence.

Her colleagues in ExperimentalNuclear Physicsled by Mark Stoyer, have helped her settle in and understand Lab procedures and processes. One facet of the Lab's postdoc program that she particularly appreciates is the ability to spend 25 percent of time in another area of interest, outside her specified field.

"I really enjoy working at LLNL and I feel that I am really taking care of my career here,"she said."Everyone is very helpful."

Pedretti has noticed the cultural differences between Italy and the United States in many ways."Here, unlike in Italy, young people have many possibilities. If they want to change their career focus, they can,"she remarks about the ease with which people not only change jobs, but move to various locations.

About CUORE, she emphasizes,"It is important that we are able to do this experiment -- it is fast and efficient and will explore a region of physics that is unknown."

"If you ask me how this (CUORE) experiment will change your life -- I can tell you, it is not an invention like the microwave oven, I mean with an immediate application. But we are on the edge of pushing many aspects of the technology and we must remember there are always byproducts and discoveries that come from science,"Pedretti says.

"Just look at what products came from men landing on the moon."

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Weak nuclear force is less weak

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The evidence for this weak nuclear force comes from the decay of muons, essentially heavier cousins of the electron, one of the building blocks of atoms.

Just as biologists sometimes study the tiniest and most ephemeral of organisms such as fruit flies, which live for barely a day, to learn things about human disease, so physicists often study the properties of particles that last a fraction of a second to learn about the universe.

The muon lives only about 2 millionths of a second -- 2 microseconds -- far from the realm of human sensation but long enough for scientists to make detailed measurements. The state of digital electronics is so advanced that measurements far shorter than this, even down to trillionths of a second or less, can easily be made.

Watching muons decay is not like propping up a Geiger counter next to a box full of radioactive uranium. That's because muons are so short lived they have to be made anew, as if they were medical isotopes. At the Paul Scherrer Institute in Switzerland a dedicatedproton beamwas used to create muons amid collisions with a graphite target.

Researchers then gathered a fine spray of muons, directed them and stopped them in their own metal target which was surrounded by a detector that could track the muons' demise. The decay of over 2 trillion muons provided the best yet value for the average muon lifetime. It comes out to 2.1969803 microseconds.

"This is the most precise lifetime determination of any state in the atomic or subatomic world,"said David Hertzog, one of the leaders of the experiment and a professor at the University of Washington in Seattle.

This lifetime, known to an uncertainty of one part per million, is so precise that it can be used to make a new determination of the intrinsic strength of the weak nuclear force, which operates over only a very short range inside the nucleus of atoms.

Scientists know of four physical forces. Gravity, a form of mutual attraction, keeps the Earth going around the sun and keeps us from floating into space. The electromagnetic force is responsible for holding atoms together, for bonding atoms into molecules, for impelling the movement of electrons through wires in the form of electricity, and for light waves. The strong nuclear force holds nuclei together and is responsible for some kinds of radioactivity.

The weak nuclear force, the fourth and last force to be discovered by physicists in the twentieth century, helps to turn protons into neutrons inside the sun, a necessary step in converting thoseprotonsinto heavier elements like helium and releasing the radiant energy that makes its way to Earth. Theweak forcealso acted billions of years ago inside exploding stars known as supernovas to make the elements such as oxygen and carbon found in our own bodies and other natural things on Earth.

The strength of the weak force is encapsulated in a number called the Fermi constant, named for the Italian-American scientist Enrico Fermi. Hertzog said that the new value for the Fermi constant is about 0.00075 percent greater than the previous value. Thus the weak force is just a tiny bit stronger than we thought.

William Marciano, a scientist at the Brookhaven National Laboratory on Long Island, N.Y. was impressed by the muon experiment.

"It was a difficult but beautiful measurement carried out by a very experienced and talented group of researchers,"Marciano said.

Marciano also points out that muons, short lived as they might be, are interesting in their own right, and actually practical. Muons were used to study the pyramids in Egypt. Muons can be created in the atmosphere by incoming cosmic rays, mysterious streams of particles from deep space. Because these muons can penetrate great amounts of material without stopping, even during their short lives, they were used as a sort of"medical scanner"for probing for hidden cavities inside the pyramid by setting up detectors above and in the basement.

Marciano said that muons might also be useful for medical imaging and for scanning cargo containers for hidden nuclear materials.

Another expert on the weak force, University of Wisconsin professor Michael Ramsey-Musolf, considers the muon experiment to be a tour-de-force piece of work. The important thing for him is that the uncertainty of the muon lifetime has now dropped by a factor of ten. But he also said that a more precise lifetime and a more precise knowledge of the strength of the weak nuclear force tells us just a bit more about nature.

"This implies that the sun does indeed burn more brightly and that the decay of nuclei is somewhat faster,"Ramsey-Musolf said.

The new muon results arescheduled to be publishedin the journalPhysical Review Letters.

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The 'Spaser' heats up laser technology

But the physical length of an ordinarylasercannot be less than one half of thewavelengthof its light, which limits its application in many industries. Now the Spaser, a new invention developed in part by Tel Aviv University, can be as small as needed to fuel nano-technologies of the future.

Prof. David Bergman of Tel Aviv University's Department of Physics and Astronomy developed and patented the theory behind the Spaser device in 2003 with Prof. Mark Stockman of Georgia State University in Atlanta. It is now being developed into a practical tool by research teams in the United States and around the world.

"Spaser"is an acronym for"surface plasmonamplificationby stimulated emission ofradiation"― and despite its mouthfilling definition, it's a number one buzzword in the nanotechnologies industry. The Spaser has been presented at recent meetings and symposia around the world, including a recent European Optical Society Annual Meeting.

Seeing your DNA up close

Spasers are considered a critical component for future technologies based on nanophotonics––technologies that could lead to radical innovations in medicine and science, such as a sensor and microscope 10 times more powerful than anything used today. A Spaser-based microscope might be so sensitive that it could see genetic base pairs in DNA.

It could also lead to computers and electronics that operate at speeds 100 times greater than today's devices, using light instead of electrons to communicate and compute. More efficient solar energy collectors in renewable energy are another proposed application.

"It rhymes with laser, but our Spaser is different,"says Prof. Bergman, who owns the Spaser patent with his American partner."Based on pure physics, it's like a laser, but much, much, much smaller."The Spaser uses surface plasma waves, whose wavelength can be much smaller than that of the light it produces. That's why a Spaser can be less than 100 nanometers, or one-tenth of a micron, long. This is much less than the wavelength of visible light, explains Prof. Bergman.

Fuelling the buzz

In the next year, the research team expects even more buzz to be created around their invention. In 2009, a team from Norfolk State University, Purdue University, and Cornell University managed to create a practical prototype.

The Spaser will extend the range of what's possible in modern electronics and optical devices, well beyond today's computer chips and memories, Prof. Bergman believes. The physical limitations of current materials are overcome in the Spaser because it uses plasmons, and not photons. With the development of surface plasma waves― electromagnetic waves combined with an electron fluid wave in a metal― future nano-devices will operate photonic circuitry on the surface of a metal. But a source of those waves will be needed. That's where the Spaser comes in.

Smaller than the wavelength oflight, nano-sized plasmonic devices will be fast and small. Currently the research team is working on commercializing their invention, which they suggest could represent a quantum leap in the development of nano-sized devices.

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Using neutron imaging to improve energy efficiency

Hassina Bilheux, a physicist and a neutron imaging scientist at ORNL, uses beam line CG-1D at the High Flux Isotope Reactor (HFIR) to image automobile engine system components, two-phase fluid components in commercial cooling systems, and electrodes used for lithium batteries.

Michael Cameron of DuPont, former chair of the SNS and HFIR Users Group, has cited applications in the auto industry and in transportation generally as highly promising for such partnerships.

Neutron imaging is just taking off at ORNL; there is currently no instrument at the laboratory devoted exclusively to it. Bilheux, the lead for developing ORNL's neutron imaging capabilities, works on industrial imaging projects with colleagues at ORNL and in industry.

CG-1D is a new facility developed in 2009 by Lee Robertson and his team in the Neutron Facilities Development Division. The CG-1 beam line runs off HFIR's HB4 Cold Source (a cold source provides neutrons cooled to a low temperature to make them move more slowly)."These are not imaging beam lines,"said Bilheux."They are not optimized for imaging. But we have been very successful since we started in December 2009 preparing CG1-D for imaging."When the neighboring beam CG 1-C becomes operational, Bilheux hopes to add it to the suite of imaging capabilities.

The CG-1D is a chopped beam instrument (i.e., neutrons are chopped into small packets, which allows their energy to be determined) and 1C is monochromatic (i.e., all the neutrons used in a single exposure have the same energy). Bilheux hopes eventually to bring neutron imaging capabilities to theSpallation Neutron Source(SNS), where she can better and more cost-efficiently select the energy of the neutrons. SNS, she says, has a wide range of energies that makes it possible to image thick biological tissues. (That type of work cannot be done at HFIR, where the neutrons would be scattered by the high hydrogen content in tissues.) The higher the energy, the deeper the penetration, and the more researchers are able to see.

"One of the goals is to bring the science to SNS, so we can develop a partnership with the medical community to explore neutron imaging capabilities for biological tissues, and eventually to work with medical doctors, such as ORNL M.D./Ph.D. Dr. Trent Nichols, and oncologists to look at tumor tissues. We are truly pioneering a new field and this is a unique time for all of us. I am very excited about all the progress we have made at CG1-D."

That progress is visible now in a series of industrial research projects already afoot or in the planning stage. Two of the projects under way involve vehicle technologies: producing 2- and 3-dimensional images of exhaust gas recirculation (EGR) coolers and images of diesel particulate filters (DPFs), which remove the black soot cloud so often associated with diesel exhaust. In both cases, the goal is to improve fuel efficiency and, in the case of the DPF project, to consider the emissions and materials impacts of the introduction of biofuels.

To take measurements, researchers set a sample in the beam and use a detector behind it to collect the neutrons that are transmitted, literally taking shadow pictures of the sample."Neutrons are especially great for engineering applications because they don't see metals very well but are efficient at seeing hydrogen-rich fluids,"Bilheux explained.

Neutron imaging is noninvasive and nondestructive: the sample-whether the engine of a car, a battery, or a component from an industrial cooling system-need not be cut into small sections for neutron imaging as it might for traditional microscopy.

In the EGR coolers project, the researchers, led by Michael Lance of ORNL's Materials Science and Technology Division, measured coolers from 10 participating companies"This is thrilling,"Bilheux said."I think this is a great success story for NScD."

Neutron imaging measures how the hydrocarbon (enriched particulate matter) is deposited within an EGR cooler that shows significant clogging. The role of the coolers is to lower the oxygen content and the combustion temperatures, thereby reducing the formation of NOx (nitrogen oxides) in the cylinder. Thanks to the imaging, the researchers can measure the thickness and hydrocarbon content of the deposit and come to understand the spatial and time dynamics of particulate matter deposition. In future measurements, tomography will be used to image complete, intact coolers in three dimensions.

A second vehicle project concerns how soot and ash build up in the DPF of a diesel-powered vehicle, and the impact of fuel type. DPFs were developed to remove the particulates (primarily soot) once common in diesel engine exhaust. Bilheux is working with Charles Finney, Andrea Strzelec (now at Pacific Northwest National Lab), and Todd Toops at the Fuels, Engines, and Emissions Research Center (FEERC) at ORNL's National Transportation Research Center. At FEERC, the researchers use diesel engines operated on dynamometer platforms to introduce particulates to the DPF. This enables the study to occur on real engines under industry-relevant conditions; additionally, field-aged samples have been provided to the FEERC researchers from industrial partners.

The work began with measurements of DPFs at different soot and ash loadings in early March. As the neutrons are able to penetrate the ceramic filter, they can take measurements of the hydrocarbon-rich particulates (soot) and metal-oxide-based ash. Although these materials are not necessarily highly sensitive to neutrons, they have a high surface area and are very hydroscopic (readily attracting moisture). The adsorbed water allows detection by neutrons. Neutron tomography is used to view and measure the thickness of the soot in the channels and the location of ash deposits. Ash, mostly from lubricant additives, affects engine efficiency by clogging the filter and increasing the backpressure on the engine and curtails filter life.

Manufacturers continually strive to create DPF control strategies to maximize theenergy efficiencyof the combined engine and aftertreatment system; the neutron tomography data further the understanding of the DPF technology to aid the optimization process.

The work is supported by DOE's Office of Energy Efficiency and Renewable Energy. The researchers hope to improve fuel efficiency and to clarify the impacts of biofuels on emissions and aftertreatment systems.

A third project entails devising strategies to improve the prediction of phase-change heat exchange, another longstanding industrial challenge. Phase-change heat exchangers, such as evaporators and condensers, are widely used in space heating, refrigeration, air conditioning, power plants, chemical plants, petrochemical plants, petroleum refineries, and natural gas processing. The performance of such equipment is difficult to predict, and testing is expensive, so components are routinely oversized to ensure they perform as required. Uncertainty about component performance prevents the optimization of system efficiencies, resulting in wasted materials and energy.

The collaboration includes researchers from the United Technologies Research Center, the research arm of United Technologies Corporation, which works on long-range technological problems afflicting U.S. industry.

"The commercial heat exchanger project is huge,"Bilheux said."When you have a fluid with vapor and liquid phases existing together in a heat exchanger, the cooling capability of that unit depends on the characteristics of the liquid-vapor interface. If we can visualize what is happening with the heat exchangers, it will give them data for model validation under true working conditions."

Heat exchangers have two-phase flow, a vapor phase and a liquid phase. These phases do not necessarily travel at the same velocity, and in many cases, the phases may be separated by the forces acting on them. These effects can exert a strong influence on the thermodynamic performance of a component and must be understood if accurate predictive models are to be developed. Using neutrons, researchers can look inside the components under operating temperature, pressure, and heat flux conditions and see where the vapor and the liquid exist. Data of this nature are very difficult to obtain using other test methods, such as optical measurements, because adding transparent walls to the component will affect the process to be measured. Neutron imaging allows direct measurement of interface characteristics with the correct wall materials and under the right thermodynamic conditions.

Finally, Bilheux is engaged with computational scientist Sreekanth Pannala and battery expert Jagjit Nanda at ORNL, as well as industry partners, to measure lithium transport inside complex electrodes.

"This is an important research area for DOE and involves substantial participation by industrial partners,"Bilheux said. Battery storage devices have excellent energy and power-to-weight ratios and are now the power source of choice for cell phones, cameras, and notebook computers. Lithium batteries are also used extensively in biomedical and military applications, and prospects are good for the use oflithium batteriesin transportation in the future.

Batteries are being studied in collaboration with Ford and GM energy storage researchers and with other cell manufacturing companies. Lithium cells in several forms- DD, cylindrical, prismatic-are being studied via neutron imaging. Scientists working at the Oak Ridge Leadership Computing Facility will plug the imaging data into their computer models of batteries to validate and refine them. The experimental data enable computational scientists to create battery models that accurately reflect what goes on in the experiments.

The researchers, who have LDRD funding, began their measurements in March 2010. They hope to reach 50 micron resolution in fall 2010, which will enable them to look at electrolyte levels and get a feel for what is going on inside a battery as they cycle it, said Bilheux.

"We want to look at the degradation and the transport of the lithium, and to give feedback for the computational models on how to build an accurate model of a lithium battery. They want to know, 'if we change the materials, how does it affect transport?' and they want to do it in situ to get a real idea of what is happening inside."

Bilheux is exactly where she wants to be."The SNS and HFIR, to me are like a train, and it is on a fast pace, and you just jump on it and go with the flow!"

She has her eye on other fields as well, hoping in the future to image ancient artifacts for the Smithsonian Museum.

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First observation of particles that are their own antiparticles could be on its way

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Researchers from the RIKEN Advanced Science Institute in Wako, Japan, have now proposed a scheme where Majorana particles could be not only observed for the first time but also manipulated. The observation would occur in a conventional material rather than space.“Our main aim is to find a platform where the existence of Majorana fermions can be shown,” explains team member Shigeki Onoda.“And beyond that, we propose concrete steps towards the control of several Majorana particles.”

In some rare materials, energetic excitations that resemble Majorana particles are predicted to exist in materials. One class of these materials is known as topological insulators on the surface of whichelectronscan travel almost unperturbed. In topological insulators that are also superconducting, Majorana particles are predicted to exist in the presence of magnetic fields. These Majorana particles can be imagined as electronic excitations that run around themagnetic fieldlines.

The device proposed by Onoda and his colleagues offers deliberate control over Majorana particles within a topological insulator that they hope will make them accessible to experiments. Their device consists of a surface of a superconducting topological insulator attached to two magnetic sections. The magnetic fields of the two magnets point in opposite directions. The researchers predict that, along the interface between the magnets, a periodic chain of magnetic field lines form in the superconducting topological insulator. Each of these magnetic field lines could accommodate a Majorana particle.

Once their existence is proved, Majorana particles could also enable extremely stable new forms of computing based on quantum physics, says Onoda.“As long as the Majorana particles are well separated, the information encoded in these states would be robust against local perturbations.”

For the time being, however, such quantum computing schemes must remain theoretical. Although widely expected to exist, superconducting topological insulators, as yet, exist only in theory. Once such a material has been found, the researchers believe that the proposed device structure will be straightforward to implement. The expected periodic arrangement of Majorana particles would then provide a convenient platform to study these elusive particles.

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Physicists take new look at the atom

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Measuring theattractive forcesbetweenatomsand surfaces with unprecedented precision, University of Arizona physicists have produced data that could refine our understanding of the structure of atoms and improve nanotechnology. The discovery has been published in the journalPhysical Review Letters.

Van der Waals forces are fundamental for chemistry, biology and physics. However, they are among the weakest knownchemical interactions, so they are notoriously hard to study. This force is so weak that it is hard to notice in everyday life. But delve into the world of micro-machines and nano-robots, and you will feel the force– everywhere.

"If you make your components small enough, eventually this van-der-Waals potential starts to become the dominant interaction,"said Vincent Lonij, a graduate student in the UA department of physics who led the research as part of his doctoral thesis.

"If you make tiny, tiny gears for a nano-robot, for example, those gears just stick together and grind to a halt. We want to better understand how this force works."

To study the van-der-Waals force, Lonij and his co-workers Will Holmgren, Cathy Klauss and associate professor of physics Alex Cronin designed a sophisticated experimental setup that can measure the interactions between single atoms and a surface. The physicists take advantage of quantum mechanics, which states that atoms can be studied and described both as particles and as waves.

"We shoot a beam of atoms through a grating, sort of like a micro-scale picket fence,"Lonij explained."As the atoms pass through the grating, they interact with the surface of the grating bars, and we can measure that interaction."

As the atoms pass through the slits in the grating, the van-der-Waals force attracts them to the bars separating the slits. Depending on how strong the interaction, it changes the atom's trajectory, just like a beam of light is bent when it passes through water or a prism.

A wave passing through the middle of the slit does so relatively unencumbered. On the other hand, if an atom wave passes close by the slit's edges, it interacts with the surface and skips a bit ahead,"out of phase,"as physicists say.

"After the atoms pass through the grating, we detect how much the waves are out of phase, which tells us how strong the van-der-Waals potential was when the atoms interacted with the surface."

Mysterious as it seems, without the van-der-Waals force, life would be impossible. For example, it helps the proteins that make up our bodies to fold into the complex structures that enable them to go about their highly specialized jobs.

Unlike magnetic attraction, which affects only metals or matter carrying an electric current, van-der-Waals forces make anything stick to anything, provided the two are extremely close to each other. Because the force is so weak, its action doesn't range beyond the scale of atoms– which is precisely the reason why there is no evidence of such a force in our everyday world and why we leave it to physicists such as Lonij to unravel its secrets.

Initially, he was driven simply by curiosity, Lonij said. When he started his project, he didn't know it would lead to a new way of measuring the forces between atoms and surfaces that may change the way physicists think about atoms.

And with a smile, he added,"I thought it would be fitting to study this force, since I am from the Netherlands; Mr. van der Waals was Dutch, too."

In addition to proving that core electrons contribute to the van-der-Waals potential, Lonij and his group made another important discovery.

Physicists around the world who are studying the structure of the atom are striving for benchmarks that enable them to test their theories about how atoms work and interact."Our measurements of atom-surface potentials can serve as such benchmarks,"Lonij explained."We can now test atomic theory in a new way."

Studying how atoms interact is difficult because they are not simply tiny balls. Instead, they are what physicists call many-body systems."An atom consists of a whole bunch of other particles, electrons, neutrons, protons, and so forth,"Lonij said.

Even though the atom as a whole holds no net electric charge, the different charged particles moving around in its interior are what create the van-der-Waals force in the first place.

"What happens is that the electrons, which hold all the negative charge, and the protons, which hold all the positive charge, are not always in the same places. So you can have tiny little differences in charge that are fluctuating very fast. If you put a charge close to a surface, you induce an image charge. In a highly simplified way, you could say the atom is attracted to its own reflection."

To physicists, who prefer things neat and clean and tractable with razor-sharp mathematics, such a system, made up from many smaller particles zooming around each other, is difficult to pin down. To add to the complication, most surfaces are not clean. As Lonij puts it,"Comparing such a dirty system to theory is a big challenge, but we figured out a way to do it anyway."

"A big criticism of this type of work always was,‘well, you're measuring this atom-surface potential, but you don't know what the surface looks like so you don't know what you're really measuring.'"

To eliminate this problem, Lonij's team used different types of atoms and looked at how each interacted with the same surface.

"Our technique gives you the ratio of potentials directly without ever knowing the potential for either of the two atoms,"he said."When I started five years ago, the uncertainty in these types of measurements was 20 percent. We brought it down to two percent."

The most significant discovery was that an atom's inner electrons, orbiting the nucleus at a closer range than the atom's outer electrons, influence the way the atom interacts with the surface.

"We show that these core electrons contribute to the atom-surface potential,"Lonij said,"which was only known in theory until now. This is the first experimental demonstration that core electrons affect atom-surface potentials."

"But what is perhaps more important,"he added,"is that you can also turn it around. We now know that the core electrons affect atom-surface potentials. We also know that these core electrons are hard to calculate in atomic theory. So we can use measurements of atom-surface potentials to make the theory better: The theory of the atom."

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Answers to black hole evolution beyond the horizon?

Dr Thomas Bäckdahl and Dr Juan A. Valiente Kroon at Queen Mary's School of Mathematical Sciences have developed a method based on properties of the Kerr solution, a time-independent solution to the equations of General Relativity.

The Kerr solution is one of the few exact solutions to the equations of General Relativity, and describes a rotating, stationary (time-independent) black hole. It is also proposed that it describes the final evolutionary stage of any dynamical (time-dependent) black hole.

General Relativity provides a unified description of gravity as a geometric property of space and time. The theory predicts the existence ofblack holesas regions in which the space and time are distorted so that nothing can escape them.

Dr Valiente Kroon, an EPSRC Advanced Research Fellow, said:"By looking at the region outside the black hole we have shown how to ascertain how much a dynamical black hole differs from the Kerr solution. There are very strong indications that the end state of the evolution of a black hole is described by this solution."The findings are reported in the journalProceedings of the Royal Society A.

The ideas developed in the article may be of relevance in developing numerical simulations of black holes, an area of research that has experienced a great development in recent years. Due to the complexity of the equations ofGeneral Relativity, these simulations are the only way of systematically exploring the theory in realistic scenarios.

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American Physical Society announces Physical Review X

As broad in scope as physics itself, PRX will publish original, high quality, scientifically sound research that advances physics and will be of value to the global multidisciplinary readership. PRX will provide validation through prompt and rigorous peer review, and anopen accessvenue in accord with the strong reputation of thePhysical Reviewfamily of publications.

PRX's Editor will be Jorge Pullin, Chair of the Horace C. Hearne, Jr. Institute forTheoretical Physicsand professor in the Louisiana State University Center for Computation&Technology and Department of Physics and Astronomy."I am very pleased to be the founding Editor,"said Pullin."I view open access options as essential for the future of publishing."Pullin received his Ph.D. from the Instituto Balseiro and has research interests in many aspects of gravitational physics, both classical and quantum mechanical. He is a fellow of the APS and AAAS, a member of APS Council, and has served on the editorial boards of a number of journals, includingLiving Reviews in RelativityandNew Journal of Physics.

Articles in PRX will be published under the terms of the Creative Commons Attribution 3.0 License, leaving copyright with the authors."Our decision to offer this license continues APS's proud history of being progressive, but responsible, regarding the rights governing the articles it publishes,"said Gene D. Sprouse, APS Editor in Chief.

The funding required to make PRX freely available will derive from article-processing charges of $1500 per article. These will cover the expenses associated withpeer review, composition, hosting, and archiving."APS strives to be among the most cost-effective publishers in physics and is committed to a sustainable model that makes PRX affordable for authors and their funding agencies, nationally and internationally,"said Joseph W. Serene, APS Treasurer/Publisher.

A Call for Papers will be issued in March and the first article published in Fall 2011.

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Italian scientists claim to have demonstrated cold fusion (w/ Video)

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Despite the intense skepticism, a small community of scientists is still investigating near-room-temperature fusion reactions. The latest news occurred last week, when Italian scientists Andrea Rossi and Sergio Focardi of the University of Bologna announced that they developed acold fusiondevice capable of producing 12,400 W of heat power with an input of just 400 W. Last Friday, the scientists held a private invitation press conference in Bologna, attended by about 50 people, where they demonstrated what they claim is a nickel-hydrogenfusion reactor. Further, the scientists say that the reactor is well beyond the research phase; they plan to start shipping commercial devices within the next three months and start mass production by the end of 2011.

The claim

Rossi and Focardi say that, when the atomic nuclei of nickel and hydrogen are fused in their reactor, the reaction produces copper and a large amount of energy. The reactor uses less than 1 gram of hydrogen and starts with about 1,000 W of electricity, which is reduced to 400 W after a few minutes. Every minute, the reaction can convert 292 grams of 20°C water into dry steam at about 101°C. Since raising the temperature of water by 80°C and converting it to steam requires about 12,400 W of power, the experiment provides a power gain of 12,400/400 = 31. As for costs, the scientists estimate that electricity can be generated at a cost of less than 1 cent/kWh, which is significantly less than coal or natural gas plants.

“The magnitude of this result suggests that there is a viable energy technology that uses commonly available materials, that does not produce carbon dioxide, and that does not produce radioactive waste and will be economical to build,” according tothis descriptionof the demonstration.

Rossi and Focardi explain that the reaction produces radiation, providing evidence that the reaction is indeed a nuclear reaction and does not work by some other method. They note that no radiation escapes due to lead shielding, and no radioactivity is left in the cell after it is turned off, so there is no nuclear waste.

The scientists explain that the reactor is turned on simply by flipping a switch and it can be operated by following a set of instructions. Commercial devices would produce 8 units of output per unit of input in order to ensure safe and reliable conditions, even though higher output is possible, as demonstrated. Several devices can be combined in series and parallel arrays to reach higher powers, and the scientists are currently manufacturing a 1 MW plant made with 125 modules. Although the reactors can be self-sustaining so that the input can be turned off, the scientists say that the reactors work better with a constant input. The reactors need to be refueled every 6 months, which the scientists say is done by their dealers.

The scientists also say that one reactor has been running continuously for two years, providing heat for a factory. They provide little detail about this case.

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One of three videos of last Friday's demonstration shows the reactor. The clicking sound is made by the water pump.

The response

Rossi and Focardi’spaperon the nuclear reactor has been rejected by peer-reviewed journals, but the scientists aren’t discouraged. They published their paper in theJournal of Nuclear Physics, an online journal founded and run by themselves, which is obviously cause for a great deal of skepticism. They say their paper was rejected because they lack a theory for how the reaction works. According to apress release in Google translate, the scientists say they cannot explain how the cold fusion is triggered,“but the presence of copper and the release of energy are witnesses.”

The fact that Rossi and Focardi chose to reveal the reactor at a press conference, and the fact that their paper lacks details on how the reactor works, has made many people uncomfortable. The demonstration has not been widely covered by the general media. However, last Saturday, the day after the demonstration, the scientists answered questions in an onlineforum, which has generated a few blog posts.

One comment in the forum contained a message from Steven E. Jones, a contemporary of Pons and Fleishmann, who wrote,“Where are the quantitative descriptions of these copper radioisotopes? What detectors were used? Have the results been replicated by independent researchers? Pardon my skepticism as I await real data.”

Steven B. Krivit, publisher of the New Energy Times,notedthat Rossi and Focardi’s reactor seems similar to a nickel-hydrogen low-energy nuclear reaction (LENR) device originally developed by Francesco Piantelli of Siena, Italy, who was not involved with the current demonstration. In a comment, Rossi denied that his reactor is similar to Piantelli’s, writing that“The proof is that I am making operating reactors, he is not.” Krivit also noted that Rossi has been accused of a few crimes, including tax fraud and illegally importing gold, which are unrelated to his research.

Rossi and Focardi have applied for apatentthat has been partially rejected in apreliminary report. According to the report,“As the invention seems, at least at first, to offend against the generally accepted laws of physics and established theories, the disclosure should be detailed enough to prove to a skilled person conversant with mainstream science and technology that the invention is indeed feasible.… In the present case, the invention does not provide experimental evidence (nor any firm theoretical basis) which would enable the skilled person to assess the viability of the invention. The description is essentially based on general statement and speculations which are not apt to provide a clear and exhaustive technical teaching.” The report also noted that not all of the patent claims were novel.

Giuseppe Levi, a nuclear physicist from INFN (Italian National Institute of Nuclear Physics), helped organize last Friday’s demonstration in Bologna. Levi confirmed that the reactor produced about 12 kW and noted that the energy was not of chemical origin since there was no measurable hydrogen consumption. Levi and other scientists plan to produce a technical report on the design and execution of their evaluation of the reactor.

Also at the demonstration was a representative of Defkalion Energy, based in Athens, who said that the company was interested in a 20 kW unit and that within two months they would make a public announcement. For the Rossi and Focardi, this kind of interest is the most important.

“We have passed already the phase to convince somebody,” Rossi wrote in his forum.“We are arrived to a product that is ready for the market. Our judge is the market. In this field the phase of the competition in the field of theories, hypothesis, conjectures etc etc is over. The competition is in the market. If somebody has a valid technology, he has not to convince people by chattering, he has to make a reactor that work and go to sell it, as we are doing.”

He directed commercial inquiries to info(at)leonardocorp1996.com .

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Which-way detector unlocks some mystery of the double-slit experiment

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As one of the most famous experiments in quantum physics, the double-slit experiment demonstrates how the quantum world is very different from the classical world. When macroscale objects are shot at a barrier with two slits, the objects travel straight through the slits and leave two straight lines on the wall behind the barrier. But whenelectronsare used instead of macroscale objects, they do not leave two straight lines on the wall but aninterference patternof many lines. Because the interference pattern remains even when the electrons are shot one at a time, the experiment seems to suggest that each electron somehow travels through both slits at the same time and interferes with itself, like a wave instead of a particle.

The second unusual part of the double-slit experiment is that the electrons stop creating an interference pattern when scientists set up a detector near one of the slits to determine which slit(s) an electron is passing through. Under these circumstances, the electrons simply create two straight lines, the same as classical particles.

Throughout the years, scientists have demonstrated different versions of the two-slit experiment. In the new study, physicists Stefano Frabboni from the University of Modena and Reggio Emilia and the CNR-Institute of Nanoscience in Modena, Italy; Gian Carlo Gazzadi from the CNR-Institute of Nanoscience; and Giulio Pozzi from the University of Bologna have presented another version of the two-slit experiment using a transmission electron microscope.

“Over the last few years, we tried to use our expertise in transmission electron microscopy and focused ion beam specimen preparation to realize some basic experiments related to some of the‘mysteries’ of quantum mechanics, as pointed out by Feynman in his celebrated lectures and books,” Frabboni toldPhysOrg.com.

First, the scientists used focused ion beam milling to make two nanoslits on a barrier. Then they modified one of the slits by covering it with a filter made of several layers of“low atomic number” material to create a which-way detector for the electrons passing through.

Although the electrons (which were shot one by one) could still pass through the filtered slit, the filter caused more of the electrons to undergo inelastic scattering rather than elastic scattering. As the physicists explained, an electron undergoing inelastic scattering is localized at the covered slit, and acts like a spherical wave after passing through the slit. In contrast, an electron passing through the unfiltered slit is more likely to undergo elastic scattering, and act like a cylindrical wave after passing through that slit. The spherical wave and cylindrical wave do not have any phase correlation, and so even if an electron passed through both slits, the two different waves that come out cannot create an interference pattern on the wall behind them.

The physicists also found that the thickness of the filter determined the interference effects: the thicker the filter, the greater the probability for inelastic scattering rather than elastic scattering, and so the fewer the interference effects. They could make the filter thick enough so that the interference effects canceled out almost completely.

“When the electron suffers inelastic scattering, it is localized; this means that its wavefunction collapses and after the measurement act, it propagates roughly as a spherical wave from the region of interaction, with no phase relation at all with other elastically or inelastically scattered electrons,” Frabboni said.“The experimental results show electrons through two slits (so two bright lines in the image when elastic and inelastic scattered electrons are collected) with negligible interference effects in the one-slit Fraunhofer diffraction pattern formed with elastic electrons.”

In a separate study, the physicists covered both slits to see if two spherical waves would create an interference pattern. They found that, in the very faint inelastic intensity, no fringes seem present, whereas interference fringes are recovered, at a very low intensity, when the elastic image is taken.

Overall, the results suggest that the type of scattering an electron undergoes determines the mark it leaves on the back wall, and that a detector at one of the slits can change the type of scattering. The physicists concluded that, while elastically scattered electrons can cause an interference pattern, the inelastically scattered electrons do not contribute to the interference process.

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Study yields better turbine spacing for large wind farms (w/ Video)

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To help steer wind farm owners in the right direction, Charles Meneveau, a Johns Hopkinsfluid mechanicsand turbulence expert, working with a colleague in Belgium, has devised a new formula through which the optimal spacing for a large array of turbines can be obtained.

"I believe our results are quite robust,"said Meneveau, who is the Louis Sardella Professor ofMechanical Engineeringin the university's Whiting School of Engineering."They indicate that large wind farm operators are going to have to space their turbines farther apart."

The newest wind farms, which can be located on land or offshore, typically use turbines with rotor diameters of about 300 feet. Currently, turbines on these large wind farms are spaced about seven rotor diameters apart. The new spacing model developed by Meneveau and Johan Meyers, an assistant professor at Katholieke Universiteit Leuven in Belgium, suggests that placing the wind turbines 15 rotor diameters apart -- more than twice as far apart as in the current layouts -- results in more cost-efficientpower generation.

Meneveau presented the study results recently at a meeting of the American Physical Society Division ofFluid Dynamics. Meyers, co-author of the study, was unable to attend.

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The research is important because large wind farms– consisting of hundreds or even thousands of turbines– are planned or already operating in the western United States, Europe and China."The early experience is that they are producing less power than expected,"Meneveau said."Some of these projects are underperforming."

Earlier computational models for large wind farm layouts were based on simply adding up what happens in the wakes of single wind turbines, Meneveau said. The new spacing model, he said, takes into account interaction of arrays of turbines with the entire atmospheric wind flow.

Meneveau and Meyers argue that the energy generated in a large wind farm has less to do with horizontal winds and is more dependent on the strong winds that the turbulence created by the tall turbines pulls down from higher up in the atmosphere. Using insights gleaned from high-performance computer simulations as well as from wind tunnel experiments, they determined that in the correct spacing, the turbines alter the landscape in a way that creates turbulence, which stirs the air and helps draw more powerful kinetic energy from higher altitudes.

The experiments were conducted in the Johns Hopkins wind tunnel, which uses a large fan to generate a stream of air. Before it enters the testing area, the air passes through an"active grid,"a curtain of perforated plates that rotate randomly and createturbulenceso that the air moving through the tunnel more closely resembles real-life wind conditions.

Air currents in the tunnel pass through a series of small three-bladed model wind turbines mounted atop posts, mimicking an array of full-sizewind turbines. Data concerning the interaction of the air currents and the model turbines is collected by using a measurement procedure called stereo particle-image-velocimetry, which requires a pair of high-resolution digital cameras, smoke and laser pulses.

Further research is needed, Meneveau said, to learn how varying temperatures can affect the generation of power on largewind farms. The Johns Hopkins professor has applied for continued funding to conduct such studies.

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Students flock to see legendary physicist Stephen Hawking

With his computerized voice, motorized wheelchair and an intellect that seems to leave mortal men far behind, Hawking is perhaps the best-known physicist ever. Die-hard fans, many of them youthful, started lining up early in the morning to get coveted free tickets to hear him speak at the California Institute of Technology Tuesday night, school be damned.

"He'll have much better things to say than our teachers,"said Palomar College engineering student Ashley Davis, who skipped class to drive up from San Marcos with three classmates for what has become an annual Caltech event.

"It's like seeing the nerd pope!"offered Evan Hetland, 13, a self-professed physics fan who came with the Shatkin family of Valencia. Fifteen-year-old Steven Shatkin sat nearby in a chair doing his science homework, holding the enviable second-position-in-line for his family, huddled in the shade.

By 2:30, three dozen people were sitting outside Beckman Auditorium, chatting with friends, playing cards and reading books. One woman did needlework.

"We figured this was a once-in-a-lifetime chance,"said Marilyn Joslyn of Los Angeles, who'd arrived early enough to nab the first place in line with three friends. Another pal came by with crackers and cheese to help them pass the time.

"I don't think we'd stand in line this long for our favorite rock star,"Joslyn said.

To many among the nerd set, of course, Hawking is a rock star. With a brain the size of a planet locked in a body that has cheated him of movement and speech, and with appearances on television shows ranging from Star Trek to the Simpsons, he has captured the imagination of masses of people who often have little idea what his research is about.

For 30 years, he held the Lucasian Chair of Mathematics at the University of Cambridge, the same chair held byIsaac Newtonin the late 1600s. He gave it up in Oct. 2009 when he reached retirement age.

His specialty is cosmology, the study of the universe, with particular emphasis on what is known as quantum gravity. He is probably most famous for his 1974 prediction that black holes should thermally create and emit subatomic particles, known today as Bekenstein-Hawking radiation, until they exhaust their energy and dissipate. In August 2009, he was awarded the U.S. Medal of Freedom, the nation's highest civilian honor, by President Barack Obama.

Hawking has been confined to a wheelchair since the early 1970s by a form of muscular dystrophy that is related to amyotrophic lateral sclerosis that has progressed over the years and has left him completely paralyzed.

In April 2007, he made a zero-gravity flight in a"Vomit Comet"of Zero Gravity Corp. during which he experienced weightlessness eight times. It was the first time in 40 years that he moved freely. Hawking said it was in preparation for a sub-orbital spaceflight on Virgin Galactic's space service. Billionaire Richard Branson had pledged to pay for the flight, which has not occurred yet.

The cosmologist created something of an uproar last year when he suggested that other intelligent species probably exist in the universe and that humans would be wise to avoid them."If aliens ever visit us, I think the outcome would be much as when Christopher Columbus first landed in America, which didn't turn out very well for the Native Americans,"he said.

By 6:30, a line of hundreds, some in wheelchairs, stretched past the lawn in front of the auditorium then snaked down a campus path toward the street, a happy anticipatory hum in the air.

Hawking's entry to the auditorium and passage in his wheelchair along the red-carpeted aisle brought whoops and clapping. Several hundred who couldn't get in the hall sat on the lawn and steps and listened to the speech remotely from outside. His formal lecture, prepared in advance, was transmitted by a voice generator in its now-familiar robot-like American accent - one that Hawking, who is British, has commented upon wryly in the past.

In addition to talking extensively about cosmology and his contributions to the field - he expressed special pride in his black hole work - Hawking also spoke of his life. He talked of his childhood and his parents: his upbringing in London and the town of St Albans; of being not the greatest student as a young child - he didn't learn to read until he was eight years old - but nonetheless being smart enough to earn the nickname"Einstein"from his classmates.

His father, a doctor of tropical medicine, had wanted the young Hawking to go into medicine also, but the youth had not felt the love."The smartest people did math and physics,"he said, to laughs from the audience.

His father, he added, had always had"a chip on his shoulder"from seeing others get ahead because of connections."Physics is different than medicine,"Hawking said."It doesn't matter what school you went to or to whom you are related. It matters what you do."

Hawking added that he was very lazy while an undergraduate at Oxford."I'm not proud of it,"he said. He received his diagnosis while in graduate school; there were times, he said, when he didn't think he would survive to complete his Ph.D.

"When you are faced with the possibility of an early death,"he said,"it makes you realize life is worth living and there are lots of things you'd like to do."

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Wave-generated 'white hole' boosts Hawking radiation theory: research

In 1974, Hawking predicted that black holes--often thought of having gravitational pulls so strong that nothing escapes from them--emit a very weak level of radiation. According to the theory, pairs of photons are torn apart by a black hole's gravitational field--one photon falls into the black hole, but the other escapes as a form of radiation.

In results outlined in the latest issue ofPhysical Review Letters, a team of UBC researchers led by international postdoctoral researcher Silke Weinfurtner put the test to Hawking's theory by creating a 'white hole' in a six-metre-long flume of flowing water.

Placing an airplane wing-shaped obstacle in the path of the flowing water created a region of high-velocity flow which blocked surface waves, generated downstream, from traveling upstream. The obstruction simulated a white hole, the temporal reverse of a black hole.

The shallow surface waves divided into pairs of deep-water waves, analogous to the photon pairs featured in Hawking's theory. Like inblack holes, they showed that the analog would also emit a thermal spectrum of radiation.

"While this creative simulation obviously doesn't prove Hawking's theory, it does show that his ideas apply broadly,"says UBCtheoretical physicistWilliam Unruh, part of the team which included European Union Marie Curie Fellow Weinfurtner, undergraduate student Matthew Penrice, Civil Engineering post doctoral fellow Edmund Tedford, and Canada Research Chair in Environmental Fluid Mechanics Gregory Lawrence.

"This experiment also exemplifies all of the strengths of UBC's research enterprise--the involvement of students, our international outreach and connections, and a very open, collaborative way of looking at scientific questions,"says Unruh.

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New territory in nuclear fission explored with ISOLDE

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In nuclearfission, the nucleus splits into two fragments (daughter nuclei), releasing a huge amount of energy.Nuclear fissionis exploited in power plants to produce energy. From the fundamental research point of view, fission is not yet fully understood decades after its discovery and its properties can still surprise nuclear physicists.

The way the process occurs can tell us a lot about the internal structure of the nucleus and the interactions taking place inside the complex nuclear structure. In particular, processes in which fission is observed at an energy just above the minimum required are the most likely to tell us which quantum corrections should be applied to the liquid-drop model (classical description) to fully understand nuclear behaviour.

At ISOLDE, an international collaboration involving scientists from nine countries has been studying the 180Tl isotope. Via radioactive decay, the thallium isotope transforms into the 180 isotope of mercury (180Hg), which subsequently fissions.“According to previous experiments and related theoretical models, we were expecting a symmetric mass distribution of the fission fragments,” says A. N. Andreyev, the principal investigator from the KU Leuven team (presently working at the University of the West of Scotland).“However, we measured an asymmetric mass distribution of the fission fragments. This discrepancy is leading us to rethink our theories on the interplay between the macroscopic liquid-drop model and the microscopic single-particle shell corrections to apply in the description of these nuclei.”

The result follows other attempts to understand similar fission processes that were made about 20 years ago by scientists in Dubna.“Previous experiments had to deal with huge amounts of contaminants in the samples of the parent element. Using ISOLDE’s unique laser ion source that makes it possible to selectively ionize elements, we can obtain a high-purity sample of 180Tl (T1/2=1.1 s). This allows us to determine with an unprecedented accuracy the different branching ratios of the various decays,” explains Andreyev.

The unexpected result of ISOLDE’s experiment will stimulate the development of new theoretical approaches to the fission process.“We have worked on a new description of the internal structure of the Hg nucleus, which is able to predict the asymmetric mass splits that we have observed. Further experiments and new theories are needed to elucidate the dynamics of the fission processes, at least for nuclei located in the region around thallium in the nuclei chart,"concludes Mark Huyse, another member of the team from KU Leuven.

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'Electron vortices' have the potential to increase conventional microscopes' capabilities

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The development opens the possibility of adaptingtransmission electron microscopy, which can see tinier details thanoptical microscopyand can study a wider range of materials than scanning probe microscopy, for quick and inexpensive imaging of a larger set of magnetic and biological materials with atomic-scale resolution.

"The spiral shape andangular momentumof these electrons will let us look at a greater variety of materials in ways that were previously inaccessible to TEM users,"said Ben McMorran, one of the authors of the forthcoming research paper."Outfitting a TEM with a nanograting like we used in our experiment could be a low-cost way to dramatically expand the microscope's capabilities."

Although NIST researchers were not the first to manipulate a beam of electrons in this way, their device was much smaller, separated the fanned out beams 10 times more widely than previous experiments, and spun up the electrons with 100 times the orbital momentum. This increase in orbital momentum enabled them to determine that the electron corkscrew, while remarkably stable, gradually spreads out over time. The group's work will be reported in the Jan. 14, 2011, issue of the journalScience.

Electrons in electron beams behave like rippling waves that move through space like a wave of light, McMorran said. Unlike wavefronts of light, which are hundreds of nanometers apart (a distance called the wavelength), the wavelengths of electrons are measured in picometers (trillionths of a meter), which make them excellent for imaging tiny objects such as atoms because of their comparable dimensions. In an ordinary electron beam, the electron wavefronts are relatively flat and uniform.

To spin up the electrons and give them orbital momentum, the NIST researchers twisted the flat electron wavefronts into a fan of helices using a very thin film with a 5-micron-diameter pattern of nanoscale slits. The pattern affects the shape of the electron wavefronts passing through it, amplifying some of the wave peaks and eliminating some of the wave valleys, to create a spiral form similar to a pasta maker extruding rotini. This method produces several electron beams fanning out in different directions, with each beam made of electrons that orbit around the direction of the beam.

The researchers knew they were successful because when they detected the electrons– which were recorded as millions of individual particles building up an image– they had formed donut-like or spiral patterns, indicating a helical shape.

Transmission electron microscopy creates images by shooting trillions of electrons through an object and measuring their absorption, deflection and energy loss. TEMs equipped with corkscrew electron beams could also monitor how the particles exert torque on a material and how a material affects the spiral shape of transmitted electrons, helping scientists build a more complete picture of the material's structure.

For example, these special electron beams have the potential to help obtain more information from magnetic materials.
"Magnetism, at its most fundamental, results from charges spinning and orbiting,"McMorran said."So anelectron beamthat itself carries angular momentum makes a good tool for probing magnetic materials."

A beam of corkscrew-shaped electrons, when interacting with a specimen, can exert torque on the material, by exchanging angular momentum with its atoms. In this way, the corkscrew electrons could obtain more information in the process than beams with ordinary electrons, which do not carry this orbital angular momentum.

This technique could also help improve TEM images of transparent objects like biological specimens. Biological material can be difficult to image in ordinary TEMs because electrons pass through it without deflecting. But by using corkscrew electron beams, researchers hope to provide high-contrast, high-resolution images of biological samples by looking at how the spiral wavefronts get distorted as they pass through such transparent objects.

While these imaging applications have not yet been demonstrated, producing corkscrew electrons with nanogratings in a TEM provides a significant step toward expanding the capabilities of existing microscopes.

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New molecular imaging technologies for detecting cellular processes

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The work carried out by these scientists has ranged from the initial design of an electronic architecture for gamma ray detectors to industry transfer of a completescanner, after having adequately validated a prototype through experimental studies at the Gregorio Marañón Hospital. The results of this research, headed by professors Juan José Vaquero and Manuel Desco, from the Department of de Bioengineering and Aerospace Engineering at UC3M, have been recently published in the journalsIEEE Transactions on Nuclear Science(two articles) andPhysics in Medicine and Biology(one article).

The electronic technology equipment designed by the researchers- which is in patent process-is based on molecular imaging, a type of biomedical imaging capable of detecting livecellular processes."These techniques differ from conventional medical imaging in that the information they show is function not form, which means that they are capable of showing the malfunctioning of an organ before the malfunction turns into an anatomical change", Juan José Vaquero explained."In other words", he added,"they allow for earlier detection of a possible anomaly, which enormously facilitates treatment". In addition to making an earlier diagnosis possible these types of scanners are used in biomedical research and in pharmaceutical laboratories, for example, to speed up the development of new medicines

The growth of molecular imaging in recent years, according to experts, is chiefly due to the narrowing of the gap between molecular biology and imaging technologies, and it is expected that an acceleration of the transfer of these techniques to clinical practice will be produced. In fact, some of the characteristics of molecular imaging itself are already present in techniques for clinical use in humans such as nuclear medicine imaging or magnetic resonance imaging."Computerized tomograhy by a sole photon emission, better known by its Anglo-Saxon acronym SPECT, is probably the most widespread molecular imagining technique in clinical practice, and from there stems the interest in having preclinical systems which allow the study of human illnesses to be carried out on animals", Professor Manuel Desco pointed out.

The Department of Bioengineering and Aerospace Engineering at UC3M focuses on the development of preclinical molecular imaging scanners used in research work on animals. Obtaining good quality in these applications constitutes a much more difficult technical challenge than with humans, due to the large difference in size (with animals being approximately 280 times smaller). The research group has completed the development of SPECT type of system for laboratory animals at University installation, which has features placing it among the top on an international scale in terms of facilities and cost.

This UC3M research group, in addition to carrying out research which leads to scientific publications, focuses a large part of its interest on technology transfer so that it can be commercialized. The company, SEDECAL, the largest domestic manufacturer and exporter of electro-medical imaging equipment, is going to commercialize the system in the immediate future. The research team from this Madrid public university continues to work on new developments in the area of technology, in close contact with national industry. Part of the developments are under the framework of the AMIT (AdvancedMolecular ImagingTechnologies) Project from the most recent CENIT public funding, whose scientific coordination oversees this equipment at the UC3M.

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Car batteries powered by relativity

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The physicists and chemists who performed the study– Rajeev Ahuja, Andreas Blomqvist, and Peter Larsson from Uppsala University in Uppsala, Sweden, and Pekka Pyykkö and Patryk Zaleski-Ejgierd from the University of Helsinki– have published their results in a recent issue ofPhysical Review Letters.

"This is a new, well-documented case of 'everyday relativity,'"Pyykkö toldPhysOrg.com. As the scientists noted in their study, the finding essentially means that"cars start due to relativity."

The lead-acid battery is the oldest type of rechargeable battery, with the main component being lead. With an atomic number of 82, lead is a heavy element. In general, relativistic effects emerge when fast electrons move near a heavy nucleus, such as that of lead. These relativistic effects include anything that depends on the speed of light (or from a mathematical perspective, anything that involves the Dirac or Schrödinger equations).

The lead-acid battery contains a positive electrode made of lead dioxide, a negative electrode made of metallic lead, and an electrolyte made of sulfuric acid. Through their calculations, the scientists found that the battery’s relativistic effects arise mainly from the lead dioxide in the positive electrode, and partly from the lead sulfate created during chemical reactions.

The discovery of relativistic effects in the lead-acid battery also sheds some light on why no corresponding“tin battery” exists. In the periodic table, tin is located directly above lead and has an atomic number of 50, making it lighter than lead. According to the scientists’ calculations, a tin battery would basically be a lead battery with very minimal relativistic effects. Although tin and lead have similar nonrelativistic energy values, tin’s small relativistic effects prohibit it from being used in an efficient battery.

As the scientists noted, relativistic effects have been found in other areas, such as the perennial yellow color of gold and the liquidity of mercury, although the latter is still not very well proven.

Overall, the scientists predicted that this understanding ofrelativity’s importance to the lead-acid battery will probably not help researchers improve thebattery; however, the insight could be useful for exploring better alternatives, especially those that involve any sixth period element (found in the sixth row of the periodic table, like lead).

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A breakthrough for terahertz semiconductor lasers

Light is nothing short of awesome -- it inspires painters and guides a midnight trip to the bathroom. Butvisible lightoccupies just one portion of theelectromagnetic spectrum. Farther along the spectrum,radio wavesenable the world to talk wirelessly. X-rays makemedical imagingpossible. Each region of the spectrum promises new technologies, if it can be harnessed.

A team led by Sushil Kumar, assistant professor of electrical and computer engineering, is helping to develop a largely unexploited region of the electromagnetic spectrum.

Working with researchers at MIT and Sandia National Laboratories, Kumar has made a semiconductor laser, also called a quantum-cascade laser (QCL), that emits terahertz (THz)radiationat higher operating temperatures than ever before. He reported his achievement recently inNature Physics.

The breakthrough moves the technology closer to applications in disease diagnosis; quality control in drug manufacturing; detection of concealed weapons, drugs and explosives; the remote sensing of the earth’s atmosphere; and the study of star and galaxy formation.

It also erases doubts that there is a maximum temperature at which coherent THz radiation can be generated from semiconductor chips.

“Terahertz QCLs are required to be cryogenically cooled and improvement of their temperature performance is the single most important research goal in the field,” the researchers wrote inNature Physics.

Progress toward a room-temperature THz laser

“Thus far, their maximum operating temperature has been empirically limited, {which} has bred speculation that a room-temperature terahertz QCL may not be possible in materials used at present.”

QCLs are attractive because of their size. Traditionally high-power THz radiation was produced by bulky, expensive lasers fueled by a molecular gas such as methane. Advances in semiconductors have made QCLs as tiny as the diode in a laser pointer, but the lasers require temperatures almost 200 degrees below zero to emit terahertz radiation.

His team has raised the QCL’s operating temperature, says Kumar, by exploiting its“tunability.”

The frequency of light generated in any material is naturally fixed and is determined by the spacing of energy levels at the molecular level. But the spacing of the QCL’s energy levels can be tuned, allowing the laser to emit THz radiation. QCLs are made of alternating layers of different semiconductors (such as gallium arsenide and aluminum gallium arsenide) because the thickness of each layer determines the spacing between the energy levels.

Proper tuning, says Kumar, is achieved by injecting electrons into the correct energy level of the semiconductor layers. The process is analogous to fuel injection in an automobile. Electrons (the fuel) hop from one energy level to another in the layered semiconductor to generate power in the form of THz photons.

But the THz photon energy, says Kumar, is much smaller than the thermal energy of electrons at room temperature.

“This makes it very difficult to selectively put electrons in the required energy levels for them to emit THz photons.”

Fuel injection -- using electrons

To raise QCLs’ operating temperature, Kumar’s group has harnessed the“relaxation process.” Electrons tend to dissipate their energy in the form of lattice vibrations at higher temperatures, called“non-radiative relaxation,” which is typically detrimental to laser operation.

Kumar’s group used this natural phenomenon in a controlled manner to inject electrons into the correctenergy levels. This scattering-assisted injection technique is less sensitive to the thermal energy of electrons and remains efficient at high temperatures as well.

“This tremendous achievement is very promising for the future of THz laser technologies,” says Alessandro Tredicucci, research director at the National Research Council of Italy and inventor of the first THz QCL.“It shows that the power of quantum design has yet to be fully tapped and encourages people to look for new materials and structures whose relaxation times can be slowed down.”

“It is remarkable how the science of QCLs has progressed hand-in-hand with advancements in crystal growth technology to make such an incredibly complex semiconductor device possible,” says John Reno of Sandia’s Center for Integrated Nanotechnologies, who coauthored theNature Physicsarticle.

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Physicists discover how the outer shell of a hornet can harvest solar power

"The interesting thing here is that a living biological creature does a thing like that,"says physicist Prof. David Bergman of Tel Aviv University's School of Physics and Astronomy, who was part of the team that made discovery."The hornet may have discovered things we do not yet know."In partnership with the late Prof. Jacob Ishay of the university's Sackler Faculty of Medicine, Prof. Bergman and his doctoral candidate Marian Plotkin engaged in a truly interdisciplinary research project to explain the biological processes that turn a hornet's abdomen intosolar cells.

The research team made the discovery several years ago, and recently tried to mimic it. The results show that the hornet's body shell, orexoskeleton, is able to harvest solarenergy. They were recently published in the German journalNaturwissenschaften.

Discovering a new system for renewable energy?

Previously, entomologists noted that Orientalwasps, unlike other wasps and bees, are active in the afternoon rather than the morning when the sun is just rising. They also noticed that the hornet digs more intensely as the sun's intensity increases.

Taking this information to the lab, the Tel Aviv University team studied weather conditions like temperature, humidity andsolar radiationto determine if and how these factors also affected the hornet's behavior, but found that UVB radiation alone dictated the change.

In the course of their research, the Tel Aviv University team also found that the yellow and brown stripes on the hornet abdomen enable a photo-voltaic effect: the brown and yellow stripes on the hornet abdomen can absorb solar radiation, and the yellow pigment transforms that into electric power.

The team determined that the brown shell of the hornet was made from grooves that split light into diverging beams. The yellow stripe on the abdomen is made from pinhole depressions, and contains a pigment called xanthopterin. Together, the light diverging grooves, pinhole depressions and xanthopterin change light into electrical energy. The shell traps the light and the pigment does the conversion.

A biological heat pump

The researchers also found a number of energy processes unique to the insect. Like air conditioners and refrigerators, the hornet has a well-developed heat pump system in its body which keeps it cooler than the outside temperature while it forages in the sun. This is something that's not easy to do, says Prof. Bergman.

To see if the solar collecting prowess of the hornet could be duplicated, the team imitated the structure of the hornet's body but had poor results in achieving the same high efficiency rates of energy collection. In the future, they plan to refine the model to see if this"bio-mimicry"can give clues to novel renewable energy solutions.

The research team also discovered that hornets use finely honed acoustic signals to guide them so they can build their combs with extraordinary precision in total darkness. Bees can at least see what they are doing, explains Prof. Bergman, but hornets cannot -- it's totally dark inside a hornet nest.

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