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Category: particle physics – Page 529

Lawrence Livermore National Laboratory (LLNL) scientists in collaboration with University of Nevada Las Vegas (UNLV) have discovered a previously unknown pressure induced phase transition for TATB that can help predict detonation performance and safety of the explosive. The research appears in the May 13 online edition of the Applied Physics Letters and it is highlighted as a cover and featured article.

1,3,5-Triamino-2,4,6- trinitrobenzene (TATB), the industry standard for an insensitive high explosive, stands out as the optimum choice when safety (insensitivity) is of utmost importance. Among similar materials with comparable explosive energy release, TATB is remarkably difficult to shock-initiate and has a low friction sensitivity. The causes of this unusual behavior are hidden in the high-pressure structural evolution of TATB. Supercomputer simulations of explosives detonating, running on the world’s most powerful machines at LLNL, depend on knowing the exact locations of the atoms in the crystal structure of an explosive. Accurate knowledge of atomic arrangement under pressure is the cornerstone for predicting the detonation performance and safety of an explosive.

The team performed experiments utilizing a diamond anvil cell, which compressed TATB single crystals to a pressure of more than 25 GPa (250,000 times atmospheric pressure). According to all previous experimental and theoretical studies, it was believed that the atomic arrangement in the crystal structure of TATB remains the same under pressure. The project team challenged the consensus in the field aiming to clarify the high-pressure structural behaviour of TATB.

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Given that everything at its base atom is moving maybe our interpretation of reality may be different than its actuality. From shooting photons bouncing off surfaces the world is a cacophony of all sorts of things happening at once.

A provocative new column in Scientific American floats the idea that what’s fundamentally real in the universe — its actual, base reality — isn’t the quarks, fields, and quantum phenomena that seem to comprise it.

Instead, according to scientist and philosopher Bernardo Kastrup, some are starting to suspect that matter itself is an illusion — and that the only real thing is information.

Information Space

The basic idea is that the physical universe exists because we perceive it — it’s a sort of mass hallucination we use to make sense of the mathematical relationships of objects.

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Dark matter is an unknown type of matter present in the universe that could be of particle origin. One of the most complete theoretical frameworks that includes a dark matter candidate is supersymmetry. Many supersymmetric models predict the existence of a new stable, invisible particle called the lightest supersymmetric particle (LSP), which has the right properties to be a dark matter particle.

The ATLAS Collaboration at CERN has recently reported two new results on searches for an LSP that exploited the experiment’s full Run 2 data sample taken at 13 TeV proton-proton collision energy. The analyses looked for the pair production of two heavy supersymmetric particles, each of which decays to observable Standard Model particles and an LSP in the detector.

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The results are fascinating and spur the imagination, but don’t start investing in flux capacitors yet. This experiment also shows us that sending even a simulated particle back in time requires serious outside manipulation. To create such an external force to manipulate even one physical particle’s quantum waves is well beyond our abilities.

“We demonstrate that time-reversing even ONE quantum particle is an unsurmountable task for nature alone,” study author Vinokur wrote to the New York Times in an email [emphasis original]. “The system comprising two particles is even more irreversible, let alone the eggs — comprising billions of particles — we break to prepare an omelet.”

A press release from the Department of Energy notes that for the “timeline required for [an external force] to spontaneously appear and properly manipulate the quantum waves” to appear in nature and unscramble an egg “would extend longer than that of the universe itself.” In other words, this technology remains bound to quantum computation. Subatomic spas that literally turn back the clock aren’t happening.

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A team of researchers from the University of Central Florida and Michigan Technological University has developed a laser system concept built on the principles of supersymmetry. In their paper published in the journal Science, the group reports that their system is meant to solve the problem of producing more light with a compact laser system. Tsampikos Kottos with Wesleyan University has written a Perspective piece on the work done by the team in the same journal issue.

Kottos points out that there are a lot of physics applications that require use of a compact laser system that also has high-output power requirements. To fulfill this need, many physicists have taken to combining multiple lasers into an array. Unfortunately, this approach suffers from the production of a lesser-quality beam. Kottos notes that one way to overcome this problem is to use selective amplification of a single mode—but doing so has its own drawbacks. In this new effort, the researchers have come up with a different approach—one based on the principles of .

Supersymmetry is a math-based theory that describes the relationship between bosons and —it suggests that for every known elementary particle, there has to be a much heavier “super partner.” To build a new kind of laser system, the researchers used this idea to create a stable array of semiconductor lasers that together offer the power needed for prospective applications. More specifically, they designed a system that emphasizes the fundamental mode by suppressing higher-order modes. They did this by pairing them with low-quality modes—their lossy super-partners. The idea was for the to support them such that they were phase-matched with the higher order modes.

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Some of the most famous scientific discoveries happened by accident. From Teflon and the microwave oven to penicillin, scientists trying to solve a problem sometimes find unexpected things. This is exactly how we created phosphorene nanoribbons – a material made from one of the universe’s basic building blocks, but that has the potential to revolutionize a wide range of technologies.

We’d been trying to separate layers of phosphorus crystals into two-dimensional sheets. Instead, our technique created tiny, tagliatelle-like ribbons one single atom thick and only 100 or so atoms across, but up to 100,000 atoms long. We spent three years honing the production process, before announcing our findings.

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Majorana particles are very peculiar members of the family of elementary particles. First predicted in 1937 by the Italian physicist Ettore Majorana, these particles belong to the group of so-called fermions, a group that also includes electrons, neutrons and protons. Majorana fermions are electrically neutral and also their own anti-particles. These exotic particles can, for example, emerge as quasi-particles in topological superconductors and represent ideal building blocks for topological quantum computers.

Going to two dimensions

On the road to such topological quantum computers based on Majorana quasi-particles, physicists from the University of W\xFCrzburg together with colleagues from Harvard University (USA) have made an important step: Whereas previous experiments in this field have mostly focused on one-dimensional systems, the teams from W\xFCrzburg and Harvard have succeeded in going to two-dimensional systems.

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Nanostructures can be designed such a way that the quantum confinement allows only certain electron energy levels. Researchers from IMDEA Nanociencia, UAM and ICMM-CSIC have, for the first time, observed a discrete pattern of electron energies in an unconfined system, which could lead to new ways of modifying the surface properties of materials.

A research group from IMDEA Nanoscience and Universidad Autónoma de Madrid has found for the first time experimental evidence that one-dimensional lattices with nanoscale periodicity can interact with the electrons from a bidimensional gas by spatially separating their different wavelengths by means of a physical phenomenon known as Bragg diffraction. This phenomenon is well-known for wave propagation in general and is responsible for the iridescent color observed upon illumination of a CD surface. Due to the wave-particle duality proposed by De Broglie in 1924, electrons also present a wave-like behavior and, thus, diffraction phenomena. Actually, the observation that low-energy free electrons undergo diffraction processes upon interaction with well-ordered atomic lattices on solid surfaces was the first experimental confirmation of the wave-particle duality.

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