Tag: subatomic particles

New Revelations From Particle Colliders Past, Present & Future

By Joseph Calamia | July 27, 2010 1:03 pm

lhc-tunnelParticle physicists hunting for the Higgs boson reported their latest findings yesterday at the International Conference on High Energy Physics in Paris. The big two–Europe’s Large Hadron Collider and Fermilab’s Tevatron Collider (in Illinois)–gave updates, and other conference buzz included talk of a new facility, the International Linear Collider, which may one day give physicists a cleaner look at the other colliders’ results.

Large Hadron Collider — More Detailed Models Help the Search

Currently operating at 7  Tera electron Volts (TeV), the Large Hadron Collider is the world’s most powerful particle accelerator. Though electrical malfunctions hindered the collider in 2008, now LHC scientists report that they have made up for lost time: finding in months, what took the Tevatron, with its 2 TeV collisions, decades.

“The scientific community thought it would take one, maybe two years to get to this level, but it happened in three months,” said Guy Wormser, a top French physicist and chairman of the conference.[AFP]

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CATEGORIZED UNDER: Physics & Math

Another Win for Quantum Mechanics: Passing the Triple-Slit Test

By Joseph Calamia | July 23, 2010 3:26 pm

rippleTo test the basics of quantum theory, physicists recently pulled out an antique. In a paper published today in Science, they confirmed a staple of quantum mechanics, using a test derived from a classic nineteenth century light experiment.

In particular, the researchers questioned how particles move through three slits, something previously too difficult to measure. They found that the particles behaved just like quantum theory–or more specifically the Born Rule–would have predicted.

As physicist Chad Orzel describes in his blog, that’s bad news for theorists hoping to tweak this rule to solve Nobel Prize-worthy problems related to quantum gravity or Grand Unifying Theories.

[The study is good news if] you’re the ghost of Max Born, or the author of an introductory quantum book…. This was disappointing news for some theorists, though, as there are a number of ways to approach problems … that would require some modification of the Born rule. [Uncertain Principles]

But how did they do it?

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The Incredible Shrinking Proton That Could Rattle the Physics World

By Andrew Moseman | July 8, 2010 10:41 am

LaserProtonIt wasn’t supposed to be like this. The Higgs boson, dark matter, neutrinos—weird or poorly understood phenomena like these seemed the likely candidates to provide a surprise that changes particle physics. Not an old standby like the proton.

But the big story this week in Nature is that we might have been wrong all along in estimating something very basic about the humble proton: its size. A team from the Paul-Scherrer Institute in Switzerland that’s been tackling this for a decade says its arduous measurements of the proton show it is 4 percent smaller than the previous best estimate. For something as simple as the size of a proton, one of the basic measurements upon with the standard model of particle physics is built, 4 percent is a vast expanse that could shake up quantum electrodynamics if it’s true.

If the [standard model] turns out to be wrong, “it would be quite revolutionary. It would mean that we know a lot less than we thought we knew,” said physicist Peter J. Mohr of the National Institute of Standards and Technology in Gaithersburg, Md., who was not involved in the research. “If it is a fundamental problem, we don’t know what the consequences are yet” [Los Angeles Times].

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LHC Sets a New Personal Record: 10,000 Particle Smash-Ups per Second

By Joseph Calamia | June 28, 2010 12:05 pm

lhc-tunnelAs a younger stronger particle smasher, the Large Hadron Collider can turn even baby steps into new records. Over this past weekend, the LHC beat another personal best–colliding its most protons yet at 10,000 particle collisions per second (about double its earlier rate). Physicists believe this is a crucial step on the collider’s hunt for new physics.

In November of 2009, the LHC collided its first protons as it started its quest to find the suspected mass-giving particle known as the Higgs Boson. The collider is still running at half of its designed maximum energy, but after this weekend, the number of particles per bunch traveling in the ring is just what physicists had planned. This is essential, says CERN physicist John Ellis:

“Protons are complicated particles, they’ve got quarks, [and other small particles], and colliding them is like colliding two garbage cans and watching carrots come out…. The more collisions we get, the closer we get to supersymmetry, dark matter, the Higgs boson and other types of new physics.” [BBC]

Here are some basics:

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Fermilab Particle Physicists Wonder: Are There 5 Higgs Bosons?

By Joseph Calamia | June 15, 2010 5:41 pm

TevatronIf the Higgs boson is the “God Particle,” then some particle physicists just turned polytheistic. To explain a recent experiment, they wonder if five Higgs bosons give our universe mass instead of one.

Last month, we discussed a curious experiment at the Tevatron particle accelerator at Fermilab near Chicago. Colliding protons and antiprotons, the Tevratron’s DZero group found more matter than antimatter.

This agrees well with common sense–if the Big Bang had really churned out equal amounts of matter and antimatter, the particles would have annihilated each other, and we wouldn’t be here. Unfortunately, the physics for this matter favoritism doesn’t make sense.

For one, it requires some fudging to fit the Standard Model, the organizing theory for particle physics. This might seem sad since we were so close to finishing the Standard Model up, with the Higgs filling the last cage in physicists’ particle zoo:

For those who believe the Standard Model is nearly complete, the discovery of the Higgs boson–a theoretical particle that imparts mass to all the other particles–would close out the final chapter. But for others who think that undiscovered physics properties exist–so-called new physics–a sequel to the Standard Model is needed. [Symmetry]

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Can Physicists Make Quantum Entanglement Visible to the Naked Eye?

By Joseph Calamia | June 6, 2010 12:02 pm

handsA pair of quantum entangled photons sure makes a cute couple. Of course, the two might have opposite states–one might be spin up and another spin down, for example–but they promise they’ll always stay that way.

They’re also fiercely loyal, respecting their opposite-spin preferences no matter how long-distance their relationship. (That means that by checking the state of one entangled photon, you can instantly know the state of the other, distant photon, a handy way to “teleport” information.) Unfortunately, because the couple is merely two light particles, their shining example of old romance has been too dim for our eyes to see.

Until now. As announced in their recently published Arxiv.org paper, physicists led by Nicolas Gisin at the University of Geneva in Switzerland believe they have found a way to watch this love affair unfold: by boosting the light emitted by one member of a quantum entangled pair, they think they can make this quantum effect visible to a human eye.

Measuring quantum states such as spin up or spin down is like looking at whether a switch is on or off. This closely matches the concept of a bit, a single 1 or 0, in computing. With entangled photons, physicists call these on/off states quantum bits or “qubits.” What an observer would see while observing an entangled photon is really a choice between two states. The observer could then confirm entanglement by checking to see that the photon was loyal to its partner.

In the traditional set-up, two widely separated particle detectors are used to measure the entanglement of the two photons. But Gisin and his colleagues want to let the human eye do some of the work.

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A Particle Physics First: Researchers Watch Neutrinos Change Flavors

By Joseph Calamia | June 1, 2010 4:28 pm

detectorFor the first time, physicists say they have witnessed a subatomic particle change its “flavor.” Physicists at OPERA, run by Italy’s national nuclear physics institute, announced yesterday that they have observed one neutrino change its type, or flavor, spontaneously. The experiment solves a 50-year-old physics mystery, and may uncover some of the universe’s hidden mass.

The Mystery

Neutrinos, which come in three different flavors, can have fairly violent births: they can come into the world via nuclear reactions in the sun, particle decay, or collisions in particle accelerators. But, once formed, they seem to ignore almost everything around them, including magnetic fields, electric fields, and matter. In fact, there are trillions of them zipping through each of us every second; they go right through our bodies and keep on moving through the planet itself.

The mystery of “neutrino oscillations” began with the number of neutrinos that should be coming from the sun. Theory predicted a certain number of various flavors to arrive, but observation showed much less:

The neutrino puzzle began with a pioneering and ultimately Nobel Prize winning experiment conducted by US scientist Ray Davis beginning in the 1960s. He observed far fewer neutrinos arriving at the Earth from the Sun than solar models predicted: either solar models were wrong, or something was happening to the neutrinos on their way. [CERN]

In 1969, Bruno Pontecorvo and Vladimir Gribov theorized that the neutrinos weren’t disappearing, they were changing their flavors mid-journey. Though physicists were looking for one type, they weren’t finding what they ordered.

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In the Universe’s Decisive Battle, Why Did Matter Prevail Over Antimatter?

By Andrew Moseman | May 21, 2010 11:13 am

TevatronAs opposed to simply energy, the universe is also made of stuff. Not a whole lot of stuff, mind you, at least if you compare the matter we experience to the vast emptiness of space or the preponderance of dark matter. But enough.

The continued prevalence of matter has long been one of my favorite attributes of the universe, given that it allows for the existence of galaxies, and Guinness. However, it’s the source of confusion to physicists. In short, there should have been equal amounts of matter and antimatter present at the creation of the universe, which doesn’t make sense:

If matter and antimatter had come out even in those first moments, they would have instantly destroyed each other, leaving nothing but energy behind [TIME].

But they didn’t; as sure as I’m sitting here, matter won out. And this week, at the Tevatron particle smasher in Illinois, a new clue to the problem has emerged. In a study for Physical Review D, physicist Dmitri Denisov and his colleagues explain that in long-running proton-antiproton collisions (nearly 8 years of them), they saw a slight favoritism toward normal matter in a particular place:

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Rumors of the LHC's Demise Have Been Greatly Exaggerated

By Andrew Moseman | March 10, 2010 10:03 am

lhcwide425It sounded again today like the Large Hadron Collider—previously the victim of technical failure, hackers, and avian sabateurs—was cursed. The BBC reported that the world’s largest particle collider would have to shut down at the end of 2011, possibly for an entire year, to address its mechanical problems, according to LHC director Steven Myers. The report states that the faults will delay the machine reaching its full potential for two years [BBC News].

Just one problem, though: While the information came out as another “LHC is broken” news break, Myers actually put forth the intended schedule more than a month ago. The LHC team announced that it would actually extend the physics run through until December 2011, before shutting the accelerator down for a year. The only real delay here has been to the reporting of the story [The Times]. Brian Cox, one of the project scientists, spent the morning tweeting up a storm in protest to the news handling of what he says is just a scheduled shutdown. (A typical tweet reads: “For the very last time – the #lhc story is a pile of merde, as we say at CERN. Scheduled maintenance stops are not bloody news!”)

The LHC will keep running until late next year at 7 trillion electron volts (TeV), as planned. The engineers will go in after that to carry out the planned maintenance on systems in the tunnel that have proven problematic so far; their improvements should allow the LHC to approach what was the goal from the start, doing physics at 14 TeV. In any case, the machine’s upcoming resting time isn’t an emergency shutdown. Particle accelerators are regularly shut down for re-engineering. They are huge, complex instruments, and it’s just impossible to run them full-time like a domestic boiler [The Times].

Related Content:
80beats: LHC Beam Zooms Past 1 Trillion Electron Volts, Sets World Record
80beats: Baguettes and Sabateurs from the Future Defeated: LHC Smashes Particles
DISCOVER: A Tumultuous Year at the LHC
Discoblog: LHC Shut Down By Wayward Baguette, Dropped By Bird Saboteur

Image: Claudia Marcelloni / CERN

CATEGORIZED UNDER: Physics & Math

Physicists Shoot Neutrinos Across Japan to an Experiment in an Abandoned Mine

By Andrew Moseman | March 1, 2010 5:26 pm

super_kamiokandeWhile the oft-troubled Large Hadron Collider is starting back up today after a weekend glitch, another big physics project is under way halfway around the world. The British and Japanese researchers behind the project called T2K (Tokai-to-Kamioka) announced their first neutrino detection, the initial step in an experiment to understand these mysterious subatomic particles.

Neutrinos are tiny particles that rarely interact with matter, making them incredibly difficult to study. But physicists have done it by looking for the signature left behind when one of the torrent of neutrinos flying through the Earth at any given time happens to crash into the nucleus of an atom within view of a neutrino detector. Japan’s Super Kamiokande is one of the largest neutrino detectors, and now it has a new mission under the T2K project. The goal is to understand a strange kind of subatomic metamorphosis. These particles come in three types or flavours: electron, muon and tau neutrinos. From earlier experiments, physicists know that neutrinos spontaneously change their flavour, oscillating back and forth from one kind to another. But the details are still hazy [New Scientist].

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CATEGORIZED UNDER: Physics & Math
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