David Kirkpatrick

August 3, 2009

Large Hadron Collider facing more problems

Filed under: Science, Technology — Tags: , , , , , — David Kirkpatrick @ 11:22 pm

This New York Times article on the Large Hadron Collider is disturbing for anyone who’s been looking forward to major scientific advancement coming out of Geneva anytime soon. I’ve done plenty of blogging on the LHC and was looking forward to it finally being up and running after the initial misfire. Looks like major problems are going to be a part of this project for a while to come.

From the first link:

The biggest, most expensive physics machine in the world is riddled with thousands of bad electrical connections.

Many of the magnets meant to whiz high-energy subatomic particles around a 17-mile underground racetrack have mysteriously lost their ability to operate at high energies.

Some physicists are deserting the European project, at least temporarily, to work at a smaller, rival machine across the ocean.

After 15 years and $9 billion, and a showy “switch-on” ceremony last September, the Large Hadron Collider, the giant particle accelerator outside Geneva, has to yet collide any particles at all.

But soon?

This week, scientists and engineers at the European Center for Nuclear Research, or CERN, are to announce how and when their machine will start running this winter.

That will be a Champagne moment. But scientists say it could be years, if ever, before the collider runs at full strength, stretching out the time it should take to achieve the collider’s main goals, like producing a particle known as the Higgs boson thought to be responsible for imbuing other elementary particles with mass, or identifying the dark matter that astronomers say makes up 25 percent of the cosmos.

The energy shortfall could also limit the collider’s ability to test more exotic ideas, like the existence of extra dimensions beyond the three of space and one of time that characterize life.

“The fact is, it’s likely to take a while to get the results we really want,” said Lisa Randall, a Harvard physicist who is an architect of the extra-dimension theory.

March 14, 2009

Stalking the Higgs boson

Filed under: Science — Tags: , , , , — David Kirkpatrick @ 2:49 pm

News from Fermilab:

Fermilab experiments constrain Higgs mass

CDF, DZero experiments exclude significant fraction of Higgs territory

Batavia, Ill.—The territory where the Higgs boson may be found continues to shrink. The latest analysis of data from the CDF and DZero collider experiments at the U.S. Department of Energy’s Fermilab now excludes a significant fraction of the allowed Higgs mass range established by earlier measurements. Those experiments predict that the Higgs particle should have a mass between 114 and 185 GeV/c2. Now the CDF and DZero results carve out a section in the middle of this range and establish that it cannot have a mass in between 160 and 170 GeV/c2.

“ The outstanding performance of the Tevatron and CDF and DZero together have produced this important result,” said Dennis Kovar, Associate Director of the Office of Science for High Energy Physics at the U.S. Department of Energy. “We’re looking forward to further Tevatron constraints on the Higgs mass.”

The Higgs particle is a keystone in the theoretical framework known as the Standard Model of particles and their interactions. According to the Standard Model, the Higgs boson explains why some elementary particles have mass and others do not.

So far, the Higgs particle has eluded direct detection. Searches at the Large Electron Positron collider at the European laboratory CERN established that the Higgs boson must weigh more than 114 GeV/c2. Calculations of quantum effects involving the Higgs boson require its mass to be less than 185 GeV/c2.

“A cornerstone of NSF’s support of particle physics is the search for the origin of mass, and this result takes us one step closer,” said Physics Division Director Joe Dehmer, of the National Science Foundation.

The observation of the Higgs particle is also one of the goals of the Large Hadron Collider experiments at CERN, which plans to record its first collision data before the end of this year.

The success of probing the Higgs territory at the Tevatron has been possible thanks to the excellent performance of the accelerator and the continuing improvements that the experimenters incorporate into the analysis of the collider data.

“Fermilab’s Tevatron collider typically produces about ten million collisions per second,” said DZero co-spokesperson Darien Wood, of Northeastern University. “The Standard Model predicts how many times a year we should expect to see the Higgs boson in our detector, and how often we should see particle signals that can mimic a Higgs. By refining our analysis techniques and by collecting more and more data, the true Higgs signal, if it exists, will sooner or later emerge.”

To increase their chances of finding the Higgs boson, the CDF and DZero scientists combine the results from their separate analyses, effectively doubling the data available.

“A particle collision at the Tevatron collider can produce a Higgs boson in many different ways, and the Higgs particle can then decay into various particles,” said CDF co-spokesperson Rob Roser, of Fermilab. “Each experiment examines more and more possibilities. Combining all of them, we hope to see a first hint of the Higgs particle.”

So far, CDF and DZero each have analyzed about three inverse femtobarns of collision data—the scientific unit that scientists use to count the number of collisions. Each experiment expects to receive a total of about 10 inverse femtobarns by the end of 2010, thanks to the superb performance of the Tevatron. The collider continues to set numerous performance records, increasing the number of proton-antiproton collisions it produces.

The Higgs search result is among approximately 70 results that the CDF and DZero collaborations presented at the annual conference on Electroweak Physics and Unified Theories known as the Rencontres de Moriond, held March 7-14. In the past year, the two experiments have produced nearly 100 publications and about 50 Ph.D.s that have advanced particle physics at the energy frontier.

Notes for editors:

Fermilab, the U.S. Department of Energy’s Fermi National Accelerator Laboratory located near Chicago, operates the Tevatron, the world’s highest-energy particle collider. The Fermi Research Alliance LLC operates Fermilab under a contract with DOE.

CDF is an international experiment of 602 physicists from 63 institutions in 15 countries. DZero is an international experiment conducted by 550 physicists from 90 institutions in 18 countries. Funding for the CDF and DZero experiments comes from DOE’s Office of Science, the National Science Foundation, and a number of international funding agencies.

CDF collaborating institutions are at http://www-cdf.fnal.gov/collaboration/index.html

DZero collaborating institutions are at http://www-d0.fnal.gov/ib/Institutions.html

Graphics, photos and videos are available at:
http://www.fnal.gov/pub/presspass/press_releases/Higgs-mass-constraints-20090313-images.html

September 9, 2008

Breaking down the Large Hadron Collider mission profile and factfile

Filed under: Science — Tags: , , , , , , , — David Kirkpatrick @ 8:47 pm

I’ve blogged quite a  bit about the Large Hadron Collider, most of it centered on covering the facts — not the fear — of what’s going to happen once the first proton hits the accelerator. And speaking of hitting, you can hit this link for all my LHC blogging.

This link covers the more exciting aspects of the LHC. Namely the mission profile for the collider and some general facts about this awesome piece of machinery.

From the link:

World’s biggest atom-smasher: Mission profile

Following is a mission profile of the Large Hadron Collider (LHC), the world’s biggest atom-smasher, which is due to start operations on Wednesday:

– Hunt for the HIGGS BOSON, a theorised particle that would explain why other particles have mass. Confirming the Higgs would fill a huge gap in the so-called Standard Model, the theory that summarises our present knowledge of particles. Over the years, scientists have whittled down the ranges of mass that the Higgs is likely to have. But they have lacked a machine capable of generating collisions powerful enough to to confirm whether this so-called God particle really does exist.

– Explore SUPERSYMMETRY, the notion that a whole bestiary of related but more massive particles exists beyond those in the Standard Model. Supersymmetry could explain one of the weirdest discoveries of recent years — that visible matter only accounts for some four percent of the cosmos. Dark matter (23 percent) and dark energy (73 percent) account for the rest. A popular theory is that dark matter comprises supersymmetric particles called neutralinos.

– Investigate the mystery of MATTER AND ANTI-MATTER. When energy transforms into matter, it produces a particle and its mirror image — called an anti-particle — which holds the opposite electrical charge. When particles and anti-particles collide, they annihilate each other in a small flash of energy. According to conventional theories of the cosmos, matter and anti-matter should exist in equal amounts, but the puzzle is that anti-matter is rare.

– Replicate the earliest moments after the BIG BANG that created the Universe. At its primal stage, matter existed as a sort of hot, dense soup called quark-gluon plasma. As it cooled, sub-atomic particles called quarks clumped together to form protons and neutrons and other composite particles. The LHC will smash heavy ions together, briefly generating temperatures 100,000 times hotter than the centre of the Sun and freeing quarks from their confinent. The researchers can then see how the liberated quarks aggregate to form ordinary matter.