Jun 25, 2009 | 15
Dark matter, written into theory to explain the behavior of massive celestial objects far above us, could be detected by heading down below—nearly a mile into the Earth. That’s the hope, anyway, of an experiment scheduled to begin next year in a South Dakota gold mine that closed in 2002.
The Sanford Underground Laboratory, dedicated this week 4,850 feet (1.5 kilometers) belowground at the Homestake Mine in Lead, S.D., will be home to the Large Underground Xenon (LUX) dark matter detector, among other experiments. Dark matter is the mysterious, invisible stuff believed to contribute roughly six times as much mass to the universe as does ordinary matter—the atoms, molecules and structures of everyday life. Its effects have been seen in its gravitational pull on large-scale structures in the universe, but its true nature remains unknown.
Mar 26, 2009 | 3
A Princeton University undergraduate working on her senior thesis found a bug in one of the detectors at the Large Hadron Collider (LHC), the gargantuan particle accelerator set to come back online before the end of the year. The Daily Princetonian reported this week that Xiaohang Quan "discovered errors that were leading to the appearances of double images" in the LHC's Compact Muon Solenoid (CMS) experiment and that Quan presented suggestions for how to fix the problem to scientists at CERN, the European lab for particle physics that operates the collider near Geneva, Switzerland.
Jan 29, 2009 | 13
One corollary of the delayed start-up of the Large Hadron Collider (LHC), the world's largest particle accelerator, is that it gives physicists—and the rest of the world—more time to mull the much-discussed possibility that the LHC could produce Earth-gobbling black holes.
In a paper posted recently to arxiv.org, physicist Roberto Casadio of the University of Bologna in Italy and his co-authors argue against such a scenario. But the bulk of the attention following their analysis has focused on their observation that microscopic LHC black holes, should they arise, could persist for seconds before decaying. (To wit, Fox News's story headlined: "Scientists Not So Sure 'Doomsday Machine' Won't Destroy World.")
Dec 5, 2008 | 13
It's official! The hobbled Large Hadron Collider (LHC) will be up and running again by next summer, according to CERN, the European lab for particle physics where the mighty LHC resides.
The info is part of a new report released today by the agency on the September incident that shuttered the world's largest particle accelerator. CERN determined in October that the LHC was done in by an electrical malfunction shortly after its initial start-up that caused a helium leak in its tunnel.
Dec 2, 2008 | 3
It's a good indication of the rabid anticipation surrounding the Large Hadron Collider (LHC) that any tidbit about the giant particle accelerator's restart is scrutinized as if it were the Zapruder film. A case in point is a single image from a 52-slide presentation given recently by Jörg Wenninger, a member of the operations group at CERN, the European lab for particle physics, where the LHC sits dormant. (An electrical malfunction that caused a helium leak crippled the accelerator shortly after it came online in September.)
The slide in question provides two scenarios, one in which the LHC starts up again as planned next summer and another in which the beam is not switched on until 2010 to allow for a full upgrade of pressure relief systems. Several blogs made note of the slide, fueling speculation that it would be a full year before the world's biggest science experiment gets under way in earnest. Not true, CERN spokesperson James Gillies told ScientificAmerican.com in an e-mail, insisting that "the LHC will start up in 2009."
Nov 21, 2008 | 20
The Standard Model of particle physics, that old workhorse of a theory, has dodged another bullet. The model lays out the properties of all known elementary particles and describes three of the four fundamental forces that govern nature (gravity is left out—finding a home for it is one of the most pressing problems in physics). But it also raises some questions—for instance, why should protons and neutrons, which make up atomic nuclei, be so heavy when their constituent parts, quarks and gluons, are so light? (In fact, the Standard Model holds that gluons are massless.)
So a team of European researchers undertook the gargantuan task of calculating the mass of so-called hadrons, such as protons and neutrons, from the bottom up, using the basic assumptions of quantum chromodynamics, the theory of how gluons bind quarks together via the strong nuclear force. (Though quarks and gluons don't have much mass on their own, they do pack energy; using Einstein's famous equation, E = mc2, that energy can be converted to mass.)
Nov 19, 2008 | 2
New results from an instrument that detects energetic particles in the upper altitudes above Antarctica show an excess of cosmic-ray electrons that may be a signal of dark matter, researchers say. The study, published today by Nature, examines data from a balloon-borne detector called ATIC (Advanced Thin Ionization Calorimeter). The unexpected wealth of electrons in a specific energy range, about 300 to 800 giga-electron-volts, points to a nearby source, the authors write.
One of the possible sources is the annihilation of dark matter, a mysterious type of particle that current theories indicate is many times more prevalent in the universe than the ordinary matter we can see and touch. Some candidates for dark matter, including the so-called Kaluza-Klein particles, would have energies that fit the bill. (The authors speculate that other astronomical objects, such as pulsars or microquasars, could also be responsible.)
Nov 17, 2008 | 1
The eagerly awaited start-up of the Large Hadron Collider (LHC), the world's largest particle accelerator, has been put off—again. The LHC was shut down in September, just days after being switched on for the first time, when an electrical malfunction caused a helium leak in the collider's tunnel. The repairs, which had been expected to last until spring, will now keep the LHC off-line into early summer, according to published statements from a spokesman for the accelerator's operator.
Oct 7, 2008 | 1
Three men who study broken symmetry -- the phenomenon that "conceals nature’s order under an apparently jumbled surface," according to the Nobel Foundation -- have won the Nobel Prize in Physics: High Energy Accelerator Research Organization (KEK), Tsukuba, Japan; and Yukawa Institute for Theoretical Physics (YITP), Kyoto University, Kyoto, Japan.
Oct 3, 2008 | 3
What if the people who run the Large Hadron Collider (LHC) threw a party, and no particles came?
That’s what is set to happen on October 21, when CERN plans an inauguration ceremony for the supercollider. After a much-ballyhooed first proton beam run on September 10, the LHC won’t actually be operational until next year, thanks to a few early mishaps. Not exactly the results LHC operators were hoping for – but why let a little thing like failure get in the way of celebrating?
A press release announcing the ceremony stressed the positive:
“It’s remarkable how quickly the LHC went through its paces on 10 September,” LHC project leader Lyn Evans said, “and testimony to the rigorous preparation that has gone into building and commissioning the LHC.”
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