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Category: particle physics – Page 184

A study from an international team led by researchers from Nagoya University in Japan and the University of New Hampshire in the United States has revealed the importance of the Earth’s upper atmosphere in determining how large geomagnetic storms develop. Their findings reveal the previously underestimated importance of the Earth’s atmosphere. Understanding the factors that cause geomagnetic storms is important because they can have a direct impact on the Earth’s magnetic field such as causing unwanted currents in the power grid and disrupting radio signals and GPS. This research may help predict the storms that will have the greatest consequences.

Scientists have long known that geomagnetic storms are associated with the activities of the Sun. Hot charged particles make up the Sun’s outer layer, the one visible to us. These particles flow out of the Sun creating the ‘solar wind’, and interact with objects in space, such as the Earth. When the particles reach the magnetic field surrounding our planet, known as the magnetosphere, they interact with it. The interactions between the charged particles and magnetic fields lead to space weather, the conditions in space that can affect the Earth and technological systems such as satellites.

An important part of the magnetosphere is the magnetotail. The magnetotail is the part of the magnetosphere that extends away from the Sun, in the direction of the solar wind flow. Inside the magnetotail is the plasma sheet region, which is full of charged particles (plasma). The plasma sheet is important because it is the source region for the particles that get into the inner magnetosphere, creating the current that causes geomagnetic storms.

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MIT researchers and colleagues have demonstrated a way to precisely control the size, composition, and other properties of nanoparticles key to the reactions involved in a variety of clean energy and environmental technologies. They did so by leveraging ion irradiation, a technique in which beams of charged particles bombard a material.

They went on to show that created this way have superior performance over their conventionally made counterparts.

“The materials we have worked on could advance several technologies, from fuel cells to generate CO2-free electricity to the production of clean hydrogen feedstocks for the [through electrolysis cells],” says Bilge Yildiz, leader of the work and a professor in MIT’s Department of Nuclear Science and Engineering and Department of Materials Science and Engineering.

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Once inflation comes to an end, and all the energy that was inherent to space itself gets converted into particles, antiparticles, photons, etc., all the Universe can do is expand and cool. Everything smashes into one another, sometimes creating new particle/antiparticle pairs, sometimes annihilating pairs back into photons or other particles, but always dropping in energy as the Universe expands.

The Universe never reaches infinitely high temperatures or densities, but still attains energies that are perhaps a trillion times greater than anything the LHC can ever produce. The tiny seed overdensities and underdensities will eventually grow into the cosmic web of stars and galaxies that exist today. 13.8 billion years ago, the Universe as-we-know-it had its beginning. The rest is our cosmic history.

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In 1973, physicist Phil Anderson hypothesized that the quantum spin liquid, or QSL, state existed on some triangular lattices, but he lacked the tools to delve deeper. Fifty years later, a team led by researchers associated with the Quantum Science Center headquartered at the Department of Energy’s Oak Ridge National Laboratory has confirmed the presence of QSL behavior in a new material with this structure, KYbSe2.

QSLs—an unusual state of matter controlled by interactions among entangled, or intrinsically linked, magnetic atoms called spins—excel at stabilizing quantum mechanical activity in KYbSe2 and other delafossites. These materials are prized for their layered triangular lattices and promising properties that could contribute to the construction of high-quality superconductors and quantum computing components.

The paper, published in Nature Physics, features researchers from ORNL; Lawrence Berkeley National Laboratory; Los Alamos National Laboratory; SLAC National Accelerator Laboratory; the University of Tennessee, Knoxville; the University of Missouri; the University of Minnesota; Stanford University; and the Rosario Physics Institute.

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The simple story line that ‘Gell-Mann and Zweig invented quarks in 1964 and the quark model was generally accepted after 1968 when deep inelastic electron scattering experiments at SLAC showed that they are real’ contains elements of the truth, but is not true. This paper describes the origins and development of the quark model until it became generally accepted in the mid-1970s, as witnessed by a spectator and some-time participant who joined the field as a graduate student in October 1964. It aims to ensure that the role of Petermann is not overlooked, and Zweig and Bjorken get the recognition they deserve, and to clarify the role of Serber.

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One of the most startling scientific discoveries of recent decades is that physics appears to be fine-tuned for life. This means that for life to be possible, certain numbers in physics had to fall within a certain, very narrow range.

One of the examples of fine-tuning which has most baffled physicists is the strength of dark energy, the force that powers the accelerating expansion of the universe.

If that force had been just a little stronger, matter couldn’t clump together. No two particles would have ever combined, meaning no stars, planets, or any kind of structural complexity, and therefore no life.

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In 2010, Mike Williams traveled from London to Amsterdam for a physics workshop. Everyone there was abuzz with the possibilities—and possible drawbacks—of machine learning, which Williams had recently proposed incorporating into the LHCb experiment. Williams, now a professor of physics and leader of an experimental group at the Massachusetts Institute of Technology, left the workshop motivated to make it work.

LHCb is one of the four main experiments at the Large Hadron Collider at CERN. Every second, inside the detectors for each of those experiments, proton beams cross 40 million times, generating hundreds of millions of proton collisions, each of which produces an array of particles flying off in different directions. Williams wanted to use machine learning to improve LHCb’s trigger system, a set of decision-making algorithms programmed to recognize and save only collisions that display interesting signals—and discard the rest.

Of the 40 million crossings, or events, that happen each second in the ATLAS and CMS detectors—the two largest particle detectors at the LHC—data from only a few thousand are saved, says Tae Min Hong, an associate professor of physics and astronomy at the University of Pittsburgh and a member of the ATLAS collaboration. “Our job in the trigger system is to never throw away anything that could be important,” he says.

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Our current best understanding of the universe requires the existence of an invisible substance known as dark matter. The exact nature of dark matter (or its actual existence) is still unknown, and there are multiple competing theories to explain the effect of this matter on the Universe. An exciting new one is called Recycled Dark Matter.

The idea behind Recycled Dark Matter is that dark matter is produced in a specific mechanism that researchers have dubbed “recycling” in a paper awaiting peer-review, because dark matter forms twice in the universe, with weird quantum mechanics and a black hole phase in the middle. All of that just a few instants after the beginning of the cosmos.

So, let’s take a journey back about 13.8 billion years. You don’t have to move, because the Big Bang happened everywhere. At the very moment that time as we know it starts ticking, the fundamental forces and the building blocks of particles we know of (the Standard Model) are in equilibrium with the Dark Sector (we know it sounds like a bad fantasy novel location, but bear with).

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