HIGGS – Could We Gain Revolutionary Insights?
Large Hadron Collider
Higgs-Particles
The "Higgs boson" tries to explain why mass exists. According to the physical theory the entire space is filled with Higgs particles. Other elementary particles interact with the Higgs particles, through which they receive a mass - imagine the difference between a human walking through air or through water. According to theory, mass is not an intrinsic property of matter, but the result of an interaction.
The LHC (Large Hadron Collider)
After over twenty years of planning and construction phase the new particle accelerator LHC (Large Hadron Collider) is in operation, a gigantic machine to re-create the Big Bang which created time and space more than 14bn years ago. As the most powerful microscope which mankind has ever constructed, this particle accelerator may deliver significant experimental data, so that finally some theoretical speculation about the fundamental structure of nature can be verified.
The LHC is being built in a circular tunnel 27 km in circumference. The tunnel is buried around 50 to 175 m. underground in the outskirts of Geneva, Switzerland and the French border.The LHC of the European Organization for Nuclear Research in Geneva is also a logistical challenge. Hundreds of research institutes and suppliers, and thousands of scientists and engineers from all over the world are cooperating to ensure a more than six billion francs (5.2 billion $) project like the LHC can succeed.
The Experiment
In the center of the experiments are fundamental questions about the structure of matter and the development and evolution of the universe after the Big Bang. What, for example, is the mysterious dark matter that dominates the universe? Why matter outweighs the amount of anti-matter in the universe? Are there more fundamental blocks of matter than known by us? And the question, what is mass?
The aim of the LHC is to continue to push our understanding of the fundamental structure of the universe.
How the LHC Works
The LHC mainly consists of a 27 km ring of superconducting magnets with a number of accelerating structures to boost the energy of the particles along the way.
In the vacuum tubes of the LHC two beams of protons (one of the constituents of atomic nuclei) are circulating in opposite directions and collide at four places in the ring with an energy of 7 trillion electronvolts (this energy has never before been reached.) There are 4 detectors installed to capture the particle tracks of the collision. The creation of matter could include exotic new particles - such as the Higgs particle, which up to now explains in theory how elementary particles become mass, but so far has never been observed and maybe could illuminate more about the constituents of matter and the state of the universe shortly after the Big Bang.
Why the LHC
What is the origin of mass? Why do tiny particles weigh the amount they do? Why do some particles have no mass at all? At present, there are no established answers to these questions. The most likely explanation may be found in the Higgs boson, a key undiscovered particle that is essential for the Standard Model to work. First hypothesized in 1964, it has yet to be observed.
For the past few decades, physicists have been able to describe with increasing detail the fundamental particles that make up the Universe and the interactions between them.
Read more at the European Organization for Nuclear Research>
Update: Sept 12, 2011
Endgame for the Higgs boson
By Susan Brown
The last missing piece of scientists’ fundamental model of particle physics is running out of places to hide.
That piece, an elementary particle called the Higgs boson that is thought to give all matter mass, has evaded detection so far. But physicists working at the Large Hadron Collider (LHC) near Geneva, Switzerland, including a contingent of more than two dozen scientists from the University of California, San Diego, have ruled out most of the range of masses the Higgs could have, leaving just a narrow span where the elusive particle might be found.
Vivek Sharma, a professor of physics at UC San Diego,
updates colleagues on the hunt for the Higgs at a
physics conference in August. Photo: Benoit Jeannet
“If it exists, it has to be there. And if it’s not there, it will be known to be science fiction by December,” Vivek Sharma, a physics professor at UC San Diego told ScienceNOW. Sharma coordinates the international team searching for Higgs boson with the CMS detector, one of two large instruments deployed in the search. The other is called ATLAS.
By speeding protons around a 27 kilometer ring at nearly the speed of light, then smashing them together, scientists fleetingly recreate conditions that prevailed when the universe began. In those moments the Higgs boson, if it exists, should pop into being and then quickly decay into other more familiar and recognizable particles, which CMS and ATLAS are poised to detect.
In just five months of the LHC running, the two teams have eliminated - at a confidence level of 95 percent - most of the range of possible masses the Higgs could have, Sharma reported at the biannual Lepton-Photon conference held recently in Mumbai. “The Higgs, if it exists, is now trapped between 114 and 145 GeV (Giga-electron volts, a measure of mass),” he said.
A Z boson - possible offspring of the Higgs - decays into
two electrons (green streaks) and two muons (red lines)
So far, scientists haven't seen enough events to be sure
they aren't just blips in background noise. Image: CERN
A Higgs boson within that range would decay in predictable ways. The scientists have observed the kinds of sprays of particles they would expect to see from a Higgs boson, but not often enough to say the events aren’t mere statistical fluctuations of well known background processes.
A definitive interpretation will require more data, which the LHC is starting to deliver. Now back in operation after a pause that has allowed the team to ramp up the rate of collisions, the machine should deliver twice as much data as has accumulated so far by the end of October.
“We are now entering a very exciting phase in the hunt for the Higgs boson,” Sharma said. “If the Higgs boson exists between 114-145 GeV, we should start seeing statistically significant excesses over estimated backgrounds and if it does not then we hope to rule it out over the entire mass range. One way or the other we are poised for a major discovery, likely by the end of this year."
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