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Category: particle physics

If “The Stellarator” sounds like an energy source of comic book legend to you, you’re not that far off. It’s the largest nuclear fusion reactor in the world, and it’s set to turn on later this month.

Housed at the Max Planck Institute in Germany, the Wendelstein 7-X (W7-X) stellarator looks more like a psychotic giant’s art project than the future of energy. Especially when you compare it with the reactor’s symmetrical, donut-shaped cousin, the tokamak. But stellarators and tokamaks work according to similar principles: In both cases, coiled superconductors are used to create a powerful magnetic cage, which serves to contain a gas as it’s heated to the ungodly temperatures needed for hydrogen atoms to fuse.

Stellarators are ridiculously hard to build, a fact which should be self-evident after one glance at the W7-X. Its 16 meter-wide ring is bristling with devices and cables of all shapes and sizes, including 250 access ports. The guts of the beast are no less chaotic: Fifty 6-ton magnetic coils, twisted and contorted like clocks in a Dalí. By comparison, the tokamak is an engineer’s dream.

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For the first time, physicists in the US have managed to measure the force that attracts antimatter particles to each other. And, surprisingly, it’s not that different to the attractive force that holds regular matter together.

The results take us one step closer to understanding one of the biggest mysteries of our Universe: why there’s so much more matter than antimatter, and suggest that the imbalance isn’t a result of antiparticles not being able to ‘stick’ together.

For every particle that exists – electrons, protons, quarks – there’s an equal and opposite antiparticle, which has the opposite electrical charge and spin, and these antiparticles make up what’s known as antimatter. When the Universe was formed, physicists believe that equal amounts of antimatter and matter were produced, but today it’s very hard to find any naturally occurring antimatter left.

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In August I went to Stephen Hawking’s public lecture in the fully packed Stockholm Opera. Hawking was wheeled onto the stage, placed in the spotlight, and delivered an entertaining presentation about black holes. The silence of the audience was interrupted only by laughter to Hawking’s well-placed jokes. It was a flawless performance with standing ovations.

In his lecture, Hawking expressed hope that he will win the Nobelprize for the discovery that black holes emit radiation. Now called “Hawking radiation,” this effect should have been detected at the LHC had black holes been produced there. But time has come, I think, for Hawking to update his slides. The ship to the promised land of micro black holes has long left the harbor, and it sunk – the LHC hasn’t seen black holes, has not, in fact, seen anything besides the Higgs.

But you don’t need black holes to see Hawking radiation. The radiation is a consequence of applying quantum field theory in a space- and time-dependent background, and you can use some other background to see the same effect. This can be done, for example, by measuring the propagation of quantum excitations in Bose-Einstein condensates. These condensates are clouds of about a billion or so ultra-cold atoms that form a fluid with basically zero viscosity. It’s as clean a system as it gets to see this effect. Handling and measuring the condensate is a big experimental challenge, but what wouldn’t you do to create a black hole in the lab?

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China has announced that it will begin construction of the world’s largest particle collider in 2020. According to officials, the subterranean facility will be at least twice the size of the Large Hadron Collider (LHC) in Switzerland, and will endeavour to find out more about the mysterious Higgs boson.

The final concept design won’t be completed until the end of next year, so we don’t have many details to go on, but the collider is expected to smash protons and electrons together at seven times the energy levels of the LHC, generating millions of Higgs bosons in the process. Best of all, the facility will reportedly be available to the entire global scientific community.

“This is a machine for the world and by the world: not a Chinese one,” Wang Yifang, director of the Institute of High Energy Physics at the China Academy of Sciences, told the government-controlled publication, China Daily, this week.

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Researchers are getting ready to turn on the world’s biggest ‘Stellarator’ fusion reactor. Called Wendelstein 7-X (W7-X), the reactor can uninterruptedly contain super-hot plasma for more than 30 minutes at a time. Scientists claim the rare design, which is contained in a giant lab in Greifswald, Germany, can finally help make fusion power a reality. Comprising super-hot plasma for long durations has been the Holy Grail for nuclear reactor designs, and can help researchers to deliver an inexhaustible source of power. Fusion reactors, for instance the W7-X, work by using two isotopes of hydrogen atoms — deuterium and tritium — and inserting that gas into a restraint vessel. Researcher then add energy that eliminates the electrons from their host atoms, creating what is described as an ion plasma, which discharges enormous amounts of energy.

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A Hall thruster is powering many of the satellites moving around Earth right now. It needs 100 million (yes, you read that right, 100 million) times less fuel than chemical thrusters. But it was never remotely sturdy enough to get anything to Mars—until now.

Typical chemical thrusters are pretty simple. Fuel combusts, gases shoot one way, and a rocket shoots the other way.

Ion thrusters are a little different. They contain charged electrodes, an anode and a cathode, and allow positively charged ions to shoot from the anode to the cathode. Thanks to momentum, the ions will “overshoot” the cathode. Under regular circumstances they’d be sucked back, but once they’ve cleared the cathode, they’re hit by a beam of electrons, neutralizing them and allowing them to go on their way without interference from the charged cathode. So the neutralized atoms shoot one way, and the rocket shoots another.

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One of the oddest predictions of quantum theory – that a system can’t change while you’re watching it – has been confirmed in an experiment by Cornell physicists. Their work opens the door to a fundamentally new method to control and manipulate the quantum states of atoms and could lead to new kinds of sensors.

The experiments were performed in the Utracold Lab of Mukund Vengalattore, assistant professor of physics, who has established Cornell’s first program to study the physics of materials cooled to temperatures as low as .000000001 degree above absolute zero. The work is described in the Oct. 2 issue of the journal Physical Review Letters

Graduate students Yogesh Patil and Srivatsan K. Chakram created and cooled a gas of about a billion Rubidium atoms inside a vacuum chamber and suspended the mass between laser beams. In that state the atoms arrange in an orderly lattice just as they would in a crystalline solid.,But at such low temperatures, the atoms can “tunnel” from place to place in the lattice. The famous Heisenberg uncertainty principle says that the position and velocity of a particle interact. Temperature is a measure of a particle’s motion. Under extreme cold velocity is almost zero, so there is a lot of flexibility in position; when you observe them, atoms are as likely to be in one place in the lattice as another.

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