China to Build Supercollider 2 - 7 Times the Energy of the Swiss Large Hadron Collider

China is planning to enter the Europe- and US-dominated world of experimental physics with (wait for it …) a bang. It has formally announced that it will begin the first phase of construction of an enormous particle accelerator around 2020, which will be twice the size and seven times more powerful than CERN's Large Hadron Collider (LHC).

Europe's LHC is the largest single machine in the world, a huge circular tunnel 17 miles (27 km) in circumference. But China's planned Circular Electron Positron Collider (CEPC) could (almost) literally run rings around it – it will be between 30 and 62 miles in circumference, large enough to circle Manhattan.

Wang Yifang, director of the Institute of High Energy Physics, Chinese Academy of Sciences, has suggested Qinhuangdao, a northern port city near the start of the Great Wall, as an ideal location for the underground facility.

The plan is for the tunnel to house two different super colliders. The first phase project will be the CEPC, designed to study the Higgs boson particle and how it decays following a collision. Super colliders smash atomic particles together at velocities close to the speed of light, to try to recreate the conditions that followed the Big Bang. China's super collider will get closer to these conditions than ever before.

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LBNL's BELLA Accelerator Sets 4.5 GeV Record

Taking careful aim with a quadrillion watt laser, researchers at the US Department of Energy’s Lawrence Berkeley National Lab claim to have managed to speed up subatomic particles to the highest energies ever recorded for a compact accelerator. By blasting plasma in their tabletop-size laser-plasma accelerator, the scientists assert that they have produced acceleration energy of around of 4.25 giga-electron volts. Acceleration of this magnitude over the short distances involved correlates to an energy rise 1,000 times greater than that of a traditional – and very much larger – particle accelerator.

The Large Hadron Collider (LHC) at CERN, for example, is some 17 miles (27 km) in circumference, and accelerates particles by way of a series of sequential, modulated electromagnetic fields contained in a metal cavity. This is perfectly fine for anything up to about 100 mega-electron volts per meter before things go awry and the metal cavity starts to break apart.

By comparison, the tiny Berkeley Lab accelerator achieves its world record by accelerating electrons inside a plasma tube just 9 cm (3.5 in) long up to a speed that would normally take an average particle accelerator many, many miles to achieve (if at all), and in a unit that sits comfortably on the top of a laboratory table.

To be fair to traditional particle accelerators, laser-plasma accelerators take a completely different approach to exciting particles to such enormous energy levels. In this case, the experiment was realized with the assistance of one of the most powerful lasers in the world, the Berkeley Lab Laser Accelerator (BELLA). This laser system produces a beam of light equivalent to a quadrillion watts of power (a petawatt), which the Berkeley researchers used to focus on the very small, straw-like tube that contained the plasma of their particle accelerator. Though, in this initial experiment, it was limited to pulses of a "mere" 0.3 PW or 300,000 gigawatts.

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Could a 35 Year old Stanford Linear Accelerator Experiment Give Clues to Dark Matter?

Here’s one reason libraries hang on to old science journals: A paper from an experiment conducted 32 years ago may shed light on the nature of dark matter, the mysterious stuff whose gravity appears to keep the galaxies from flying apart. The old data put a crimp in the newfangled concept of a "dark photon" and suggest that a simple bargain-basement experiment could put the idea to the test.

No one really knows what dark matter is. Since the 1980s, theorists' best hunch has been that it consists of so-called weakly interacting massive particles, or WIMPs. If they exist, WIMPs would have a mass between one and 1000 times that of a proton. They would interact only through the feeble weak nuclear force—one of two forces of nature that ordinarily flex their muscle only within the atomic nucleus—and could disappear only by colliding and annihilating one another. So if the infant universe cooked up lots of WIMPs, enough of them would naturally survive to produce the right amount of dark matter today. But physicists have yet to spot WIMPs, which every now and then should ping off atomic nuclei in sensitive detectors and send them flying.

More recently, theorists have explored other ideas, such as self-interacting dark matter. This would consist of a particle, known as a χ (pronounced chi), with a mass between 1/1000 and one times that of the proton. Those particles would interact with one another through a force like the electromagnetic force, which produces light. That force would be conveyed by a massive particle called a dark photon—a dark matter version of a particle of light—that might "mix" slightly with the ordinary ones. So with some small probability, a dark photon might interact with ordinary charged particles such as electrons and atomic nuclei—just as ordinary photons do.

Self-interacting dark matter has attractive properties. In particular, a dark photon could also explain a particle physics puzzle. A particle called the muon appears to be very slightly more magnetic than theory predicts, and that discrepancy could be resolved if the muon interacts with dark photons lurking in the vacuum. However, χs and dark photons would be hard to detect with WIMP detectors; with their low masses, they couldn't whack a nucleus hard enough to create a signal.

But archival data already rule out dark photons with certain combinations of properties, argues Rouven Essig, a theoretical physicist at Stony Brook University in New York, and his colleagues. The data come from E137, a "beam dump" experiment that ran from 1980 to 1982 at SLAC National Accelerator Laboratory in Menlo Park, California. In the experiment, physicists slammed a beam of high-energy electrons, left over from other experiments, into an aluminum target to see what would come out. Researchers placed a detector 383 meters behind the target, on the other side of a sandstone hill 179 meters thick that blocked any ordinary particles. They then looked for hypothetical particles called axions, which would have pierced the earth and reached the detector—and saw none.

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LBNL Proposing new Laser-Plasma Accelerator

It took every inch of the Large Hadron Collider's 17-mile length to accelerate particles to energies high enough to discover the Higgs boson. Now, imagine an accelerator that could do the same thing in, say, the length of a football field. Or less.

That is the promise of laser-plasma accelerators, which use lasers instead of high-power radio-frequency waves to energize electrons in very short distances. Scientists have grappled with building these devices for two decades, and a new theoretical study predicts that this may be easier than previously thought.

The authors are Carlo Benedetti, Carl Schroeder, Eric Esarey, and Wim Leemans, physicists at Lawrence Berkeley National Laboratory's Berkeley Lab Laser Accelerator (BELLA) Center. Their paper, "Plasma wakefields driven by an incoherent combination of laser pulses: A path towards high-average power laser-plasma accelerators," appears in the May Special Issue of Physics of Plasmas, from AIP Publishing.

If their models prove correct, they could help lower the cost of high-energy physics research -- the Large Hadron Collider cost $9 billion -- as well as many other industrial and medical applications of accelerators.

Laser-plasma accelerators work by blasting a powerful laser beam into a plasma, a cloud of unattached electrons and ions.

"The effect is like the wake of boat speeding down a lake. If the wake was big enough, a surfer could ride it," Leemans, who heads the BELLA Center, explained.

"Imagine that the plasma is the lake and the laser is the motorboat. When the laser plows through the plasma, the pressure created by its photons pushes the electrons out of the way. They wind up surfing the wake, or wakefield, created by the laser as it moves down the accelerator," he said.

The fast moving electrons leave the heavy ions behind. As they separate, they create gigantic electric fields, 100 to 1,000 times larger than those in conventional accelerators.

This is how they accelerate electrons so rapidly. For example, Stanford's Linear Accelerator Center takes two miles to drive an electron to 50 billion electron volts (GeV). Leemans' experimental laser-plasma accelerator takes electrons to more than 1 GeV in slightly more than 1 inch.

It takes a lot of laser power to generate a wakefield. For example, BELLA's petawatt (1 quadrillion watts) laser has a 10 meter x 10 meter footprint. It generates 400 times more power than all the world's power plants combined, though only for 40 femtoseconds (40 quadrillionths of a second).

Unfortunately, it takes BELLA's laser a full second to recharge and send a second pulse. High-energy physics research requires tens of thousands of pulses per second. Many other applications would benefit from multiple pulses per second.

BELLA's laser has the highest repetition rate of any petawatt laser in the world. Building a faster petawatt laser would require a heroic feat of engineering.

Several European researchers have suggested using an array of smaller lasers to produce one enormous pulse. Since less powerful lasers recharge faster, they could produce hundreds or even thousands of pulses per second and sustain a wakefield over many meters.

The hurdle they needed to overcome was how to synchronize hundreds of lasers so they all pulsed within less than a femtosecond of one another.

Such precision would be expensive and presents serious technical problems. But the concept of combining lasers got Leemans' team thinking.

What if the beam was not perfect? What if it were just good enough to rapidly raise the photon pressure on the electrons? Could we get away with it, they wondered.

According to the model presented in Physics of Plasmas, they could. Leemans compares it to pushing a swing.

"Instead of one big push, we would give it many smaller pushes at roughly the same time. It's not quite perfect, but the swing doesn't really care. It averages over all these little pushes and up it goes."

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Physicists Discover Method to Create Matter From Light

Imperial College London physicists have discovered how to create matter from light - a feat thought impossible when the idea was first theorised 80 years ago.

In just one day over several cups of coffee in a tiny office in Imperial's Blackett Physics Laboratory, three physicists worked out a relatively simple way to physically prove a theory first devised by scientists Breit and Wheeler in 1934.

Breit and Wheeler suggested that it should be possible to turn light into matter by smashing together only two particles of light (photons), to create an electron and a positron – the simplest method of turning light into matter ever predicted. The calculation was found to be theoretically sound but Breit and Wheeler said that they never expected anybody to physically demonstrate their prediction. It has never been observed in the laboratory and past experiments to test it have required the addition of massive high-energy particles.

The new research, published in Nature Photonics, shows for the first time how Breit and Wheeler's theory could be proven in practice. This 'photon-photon collider', which would convert light directly into matter using technology that is already available, would be a new type of high-energy physics experiment. This experiment would recreate a process that was important in the first 100 seconds of the universe and that is also seen in gamma ray bursts, which are the biggest explosions in the universe and one of physics' greatest unsolved mysteries.

The scientists had been investigating unrelated problems in fusion energy when they realised what they were working on could be applied to the Breit-Wheeler theory. The breakthrough was achieved in collaboration with a fellow theoretical physicist from the Max Planck Institute for Nuclear Physics, who happened to be visiting Imperial.

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CERN Hears Snowmass and Wants to Build 80 km, 100TeV TLEP Collider

Not content with the 27-kilometre-round Large Hadron Collider, researchers at CERN have their sights set on a new beast of a particle collider that could have a circumference of 80 to 100 kilometres.

The nuclear research organisation announced that it was hatching plans for an ambitious successor to the LHC with an international study called the Future Circular Colliders (FCC) programme, which will kick off with a meeting next week.

The idea is to consider different hadron collider designs similar to the existing LHC but more powerful—much more powerful. CERN wrote it was looking for a collider “capable of reaching unprecedented energies in the region of 100 TeV.” The existing LHC will reach a maximum of around 14 TeV (tera electron Volts).

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Sounds like the SSC!  Even down to the length!  Our tunnel is partially built!  C'mon!  Let's get into a science race with the Euros!  F*ck the EU!  Ahem.  ;)

Snowmass: Let us Have the Very Large Hadron Collider!

When Europe’s Large Hadron Collider (LHC) started up in 2008, particle physicists would not have dreamt of asking for something bigger until they got their US$5-billion machine to work. But with the 2012 discovery of the Higgs boson, the LHC has fulfilled its original promise — and physicists are beginning to get excited about designing a machine that might one day succeed it: the Very Large Hadron Collider (VLHC).

“It’s only prudent to try to sketch a vision decades into the future,” says Michael Peskin, a theoretical physicist at SLAC National Accelerator Laboratory in Menlo Park, California, who presented the VLHC concept to a US government advisory panel on 2 November.

The giant machine would dwarf all of its predecessors (see ‘Lord of the rings’). It would collide protons at energies around 100 teraelectronvolts (TeV), compared with the planned 14 TeV of the LHC at CERN, Europe’s particle-physics lab near Geneva in Switzerland. And it would require a tunnel 80–100 kilometers around, compared with the LHC’s 27-km circumference. For the past decade or so, there has been little research money available worldwide to develop the concept. But this summer, at the Snowmass meeting in Minneapolis, Minnesota — where hundreds of particle physicists assembled to dream up machines for their field’s long-term future — the VLHC concept stood out as a favorite.

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The diameter sounds suspiciously like the old SSC.  Perhaps some crazy person in Texas ought to pitch their congress critter...;)

The Surprise of the Higgs Boson is There are NO Surprises