"We may get indications that are not consistent with its non-existence."
-- Sergio Bertolucci, director of research, CERN
The European Center for High Energy Research (CERN) was abuzz with rumor that evidence for the long-sought Higgs boson was found. Evidence of its existence lies in the petabytes of data taken over the last few years. High energy head on collisions between protons and neutrons cause them to decompose into exotic quark combinations, as well as the force particles that hold them together - the gluons that make up the porridge that is a quark-gluon plasma. The energies are unimaginably high - collisions were at energy levels up to 7 tera-electron-volts (TeV) - and the time scales fantastically small - things happen in pico-seconds (ps).
The beams of protons - actually nuclei of heavy atoms like lead that are stripped of all of their electrons, so that only bare nuclei are being accelerated - are only 16 microns in diameter, but the detection apparatus that surrounds the collisions is huge. Collision events cause a spray of particles radially around the collision centers, and the detectors detect charged particles flying by, as well as the incremental heat rises in calorimeters as some particles are stopped by the masses in the detectors. There are two detectors that surround each other in concentric shells: the Compact Muon Solenoid (CMS) and ATLAS, an acronym that's so tortured I can't even repeat what it stands for. Two completely different detectors, operated by two teams of physicists who collect and study data independently of one another, to ensure the highest standards of scientific integrity of their findings.
Evidence for the existence of a Higgs boson, if it exists, and no one is even sure that it does, has been likened to finding a needle in a haystack of haystacks. The detectors take data at a rate of a petabyte per second. The computers in the front ends of the detectors distill this data, so that the net resultant data flow is about 700 MB/sec. There are petabytes of data floating around. Carl Sagan's "bill-yuns and bill-yuns" expression pales in comparison to the amount of data that CERN is churning out when its accelerator is running.
So the data just sits there, and it takes months and years to sift through it. Out of this Olympic-sized mountain of data, computers running special algorithms find, and then discard, most collisions (and their products, and then decays into daughter particles). Occasionally, though, they'll get some combination of particles that are the right combinations, at the right energy levels, that could be reactions they haven't seen before, and this offers a possibility. If it's above 114 GeV and below 140 GeV, the lower and upper energy levels for the Higgs up to now - the levels are set by a combination of theoretical reasons and experimental ones - then the entire mise en scene is presented to researches, who look at the collisions far more carefully.
Apparently, they found a few events that look like the Higgs.
Physicists aren't good at keeping poker faces. There has been a buzz in the particle physics community, and when that happens, reporters start appearing and crawling around CERN asking annoying questions.
Sergio Bertolucci was being guarded when a BBC reporter asked him about whether or not CERN had found a Higgs:
"It's too early to say... I think we may get indications that are not consistent with its non-existence.
"This hunt for the Higgs is like fishing in an ancient way… instead of using modern tools you are removing the water from the pond… it might look tedious but it is the only way, at the end of the day, when you have removed all the water from the pond to find the smallest fish."
Stay tuned. CERN has hosting a presentation of data next week, on Tuesday, Dec. 13, 2011. There will probably be live feeds you can watch. Might be cool to see this live. History is happening in front of you...
SOURCES
- Susan Watts, "Cern scientist expects 'first glimpse' of Higgs boson," BBC News, Dec. 7, 2011
- Tommaso Dorigo, "Fundamental Glossary For The Higgs Broadcast," Science 2.0, Dec. 9, 2011. Tommaso Dorigo is a particle physicist working at CERN. This is his blog about CERN. He's anticipating the broadcast next week and helping his readers understand some of the confusing technical argot unique to the world of high energy experimental physics.
- Adam Mann, "Could a Higgs Boson Announcement Be Imminent From the LHC?," Wired Science, Dec. 2, 2011
- Robert Garisto, "How Do Eminent Physicists Tackle the Higgs Boson? With Chocolate," New York Times, Nov. 28, 2011
- Ian Sample, "Higgs boson's moment of truth is fast approaching at the LHC," The Guardian UK, Nov. 18, 2011. A nice photograph of Scottish physicist Peter Higgs, the theoretical physicist credited with his eponymous particle.
- Ian Sample, "Is the Higgs boson Real?," The Guardian UK, Dec. 6, 2011. Excellent quotes from leading physicists on the likelihood of the discovery of the Higgs boson. Quotes (and a limerick) from Sheldon Glashow, Lisa Randall, Frank Wilczek, Philip Anderson, Martinus Veltman and Gerard t'Hooft.
- Kathryn Grim, "Favored Higgs hiding spot remains after most complete search yet," Symmetry Magazine, Nov. 18, 2011. The best and most sciencey news article yet on the search for the Higgs, and how the dragnet is tightening
- Robert Evans, "Search narrowed for Higgs: does it exist?," Reuters, Nov. 24, 2011