Particle physicists have ruled out one of the possible remaining hiding places of the Higgs boson, bringing them one step closer to finding the slippery subatomic particle–or, conceivably, to ruling out its existence.
Physicists believe that the Higgs particle interacts with some other particles, like the W and Z bosons, to give them mass. The standard quip about the Higgs is that it is the “God Particle” — it is everywhere but remains frustratingly elusive. Confirming the Higgs would fill a huge gap in the so-called Standard Model, the theory that summarizes our present knowledge of particles [AFP].
The new results, from the Tevatron particle accelerator at the Fermi National Accelerator Laboratory, narrow down the range of masses where the Higgs boson may be found. Physicist Craig Blocker explains that particle accelerators smash particles together and then sift through the debris produced, looking for particles with certain masses. Previous collider experiments had placed a lower bound of 114 giga-electron volts (GeV), a measure that can be used for particle mass, on the Higgs, and theoretical calculations require it to be less than 185 GeV. The new Fermilab results, from its Tevatron collider, rule out a Higgs mass between 160 and 170 GeV…. “If the Higgs had a mass in this fairly narrow range” of 160 to 170 GeV, he says, “we should have seen it, we had a good chance to see it” [Scientific American].
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After all the excitement and anticipation surrounding the Large Hadron Collider‘s launch last September, its first few months have been an anticlimactic cascade of disappointments. When a fault shut down the subatomic particle collider just nine days after the first beam of protons whizzed around its 17-mile track, officials at first said it would take several weeks to repair. Then they revised that estimate, saying it wouldn’t be fixed until spring of 2009–and then that changed to summer of 2009. Now, officials say that repairs won’t be finished before September, at the earliest.
To appease impatient high-energy physicists, the laboratory will probably run the machine (albeit at reduced powers) for a ten-month stretch from November until the autumn of 2010 [Nature News]. Officials at CERN, the European agency that runs the collider, hadn’t planned to run it through the winters when electricity costs are higher; they estimate that this appeasement will cost them an extra $10.5 million for electricity.
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The standard model of physics got it right when it predicted where the mass of ordinary matter comes from, according to a massive new computational effort. Particle physics explains that the bulk of atoms is made up of protons and neutrons, which are themselves composed of smaller particles known as quarks, which in turn are bound by gluons. The odd thing is this: the mass of gluons is zero and the mass of quarks [accounts for] only five percent. Where, therefore, is the missing 95 percent? [AFP]
The answer, according to theory, is that the energy from the interactions between quarks and gluons accounts for the excess mass (because as Einstein‘s famous E=mc² equation proved, energy and mass are equivalent). Gluons are the carriers of the strong nuclear force that binds three quarks together to form one proton or neutron; these gluons are constantly popping into existence and disappearing again. The energy of these vacuum fluctuations has to be included in the total mass of the proton and neutron [New Scientist]. The new study finally crunched the numbers on how much energy is created in these fluctuations and confirmed the theory, but it took a supercomputer over a year to do so.
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Fixing the glitches that shut down the Large Hadron Collider (LHC) in September will apparently be no easy task: A spokesman for the particle physics lab CERN has announced that the repairs will cost $21 million and will probably not be completed until late June. Cern spokesman James Gillies said: “If we can do it sooner, all well and good. But I think we can do it realistically (in) early summer” [BBC News].
The startup of the LHC on September 10th may win an award for anticlimax of the year: Physicists talked for months about the mysteries of physics that the particle collider would reveal, while nervous laypeople worried that when engineers flipped the switch on the machine it would create a miniature black hole that could destroy the earth. But instead of either of these scenarios coming true, the LHC broke within two weeks before getting a chance to perform any experiments.
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Strange things are afoot at the Tevatron particle collider at Fermilab, and the aging U.S. particle smasher is getting an unexpected moment in the spotlight while physicists wait for the repairs of the Large Hadron Collider in Switzerland. Researchers say experiments at the Tevatron have produced particles that they are unable to explain using the standard model of physics, and say it’s possible that they’ve detected a previously unknown particle. If the result does turn out to be due to some unexpected new process, it would be the most significant discovery in particle physics for decades [Physics World].
Bloggers and theorists are already lining up explanations that involve unseen particles, hypothetical strings, or modifications of conventional physics. The finding is so controversial that about one-third of the 600-person experiment that detected it are refusing to put their names on the 69-page paper purporting its discovery [Nature News], which was posted in advance of publication on the server arXiv.
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The accident that brought the Large Hadron Collider‘s particle-smashing experiments to a screeching halt on Friday will keep the collider out of action until spring 2009, officials at CERN announced today. A preliminary inquiry has revealed that it will take two months to fix the problem and restore operating conditions, and the LHC was already scheduled to shut down in the winter to reduce electrical costs.
Says CERN spokesman James Gillies: “We are not going to be done with this before the winter shutdown, so there will be no more beam in the LHC this year…. The winter shutdown will go according to schedule, which means that we start up the accelerator complex in the spring months” [AP].
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The vaunted Large Hadron Collider (LHC) experienced a significant setback this morning, when temperatures in one sector of the particle collider began to rise, and a ton of liquid helium escaped into one area of the collider’s 17-mile tunnel. The mishap follows a previous glitch that occurred one day after the LHC’s opening and delayed operations for about a week, but this new incident appears to be more serious and could take several weeks to resolve.
The LHC smashes subatomic particles together by send protons whizzing through its circular tunnel to collide at certain points; the beams of protons are kept on track by over 1,600 massive magnets that must be kept at temperature near zero on the Kelvin scale. The incident was what is known as a “quench”, in which the temperature of superconducting magnets that are normally chilled to 1.9C above absolute zero started to rise. It caused the temperature of many of the 200 or so magnets in the affected sector to soar by as much as 100C, which would normally take about two weeks to be cooled again [The Times]. The LHC’s operating organization, known as CERN, hasn’t yet revealed the cause of the incident.
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Today at 10 a.m. Swiss time, researchers fired up the Large Hadron Collider (LHC), successfully sending a stream of protons all the way around a 17-mile track for the first time. The enormous collider has been eagerly anticipated by physicists, who hope the device will answer questions about the behavior of subatomic particles and reveal secrets of the universe, but some people have also worried (needlessly, physicists say) that its unprecedented experiments will cause the world to end. For all that hype, the action today was somewhat anticlimatic: Two white dots flashed on a computer screen indicating that the protons reached the final point of the world’s largest particle collider [AP].
As many scientists have pointed out, today’s test run didn’t involve any actual collisions; those will come later when particles shoot around the track in both directions and smash into each other. Therefore today’s event could never have produced any breathtaking results, it was simply intended to test the equipment.
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After 15 years of construction, the world’s largest particle accelerator is warmed up, fully tested, and ready to rumble. The Large Hadron Collider will go into operation on September 10th, and researchers are celebrating every step towards that momentous day. Last weekend, physicists popped champagne to toast the results of a test in which beams of protons were sent barreling into a massive block of concrete, causing the protons to fragment into smaller particles. Researchers have also successfully sent test batches of protons part-way around the collider’s 17-mile circular track.
The Large Hadron Collider represents the science world’s latest, greatest attempt to smash its way into the mysteries of the universe: Beams of protons will eventually collide with the energy of two bullet trains – spawning sprays of subatomic debris that are certain to lead to new discoveries…. One experiment at the LHC, known as ALICE, seeks to re-create the conditions that existed just an instant after the big bang that gave rise to the universe as we know it. [The collider's] researchers want to understand why matter won out over antimatter after the creation of the cosmos [MSNBC].
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Scientists at CERN had said all along that they planned to activate the Larger Hadron Collider this summer. Now it looks like they’ll slide in just before the official end of the season. The world’s most powerful particle accelerator, aimed at unlocking secrets of the universe, will be launched on September 10 [Reuters].
“We’re finishing a marathon with a sprint,” said project leader Lyn Evans. “It’s been a long haul, and we’re all eager to get the LHC research program under way” [San Jose Mercury News].
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Well, that’s a relief. After a long safety review, physicists have declared that the enormous atom smasher that’s expected to go online this fall won’t create tiny black holes that will “eat” our planet. So that’s one less thing to worry about.
The Large Hadron Collider, which is being built near Geneva, Switzerland, will do things with subatomic particles that humans have never done before, causing some people to worry that scientists might be unwittingly building a doomsday devise. The $8 billion machine is designed to accelerate protons, the building blocks of ordinary matter, to energies of 7 trillion electron volts and then bang them together to produce tiny primordial fireballs, miniature versions of the Big Bang. Physicists will comb the detritus from those fireballs in search of forces and particles and even new laws of nature that might have prevailed during the first trillionth of a second of time [The New York Times].
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