Wednesday, March 31, 2010

Smashing!

"Smashing" is a European exclamation that I wish had caught on in the states. It just seems to have a certain ring to it...but maybe that's because it reminds me of physics.

I can't think of a better word to express my excitement and joy for the big announcement this week from CERN. The LHC swung those little protons around that 26 kilometer track aaaannnnndddd....SMASHING! Yes, the LHC is officially colliding particles at (another) record breaking (but a little more breath taking) energy of 7 TeV!!!

I would give you a round up of stories on this subject, but the Knight Science Journalism Tracker has done far better a job, so I'll just point you there. KSJT also pointed out how interesting the collision images are looking. Instead of boring spikes on nameless graphs, we are getting some really lovely and illustrative images from the experiments located on the LHC - ATLAS, ALICE, CMS and LHCb.

The LHC already holds the world record for highest energy collisions - in November 2009 it went just a hair above the Tevatron's 1 TeV energy and reach a still stunning 1.18 TeV.

Cosmic rays strike our atmosphere at even higher energies than those created in the LHC - a point made by physicists dispelling ideas that these collisions could create black holes that might eat the Earth. And those are very energetic collisions - relatively.

1 TeV (1x10^12) is not a great amount of energy to us. It's about the amount of energy possessed by a slow moving ant. If you nearly double that energy, up to about 3x10^20 eV, you would have about the amount of energy possessed by a bowling ball if you held it at your waist and dropped it.

These big accelerators are so amazing, and cost so much money, because they put all that energy into individual particles. There are roughly 3x10^28 protons in your body. Even if only one very slow ant is nothing to worry about, if you could get that many of them together, you'd have some fightin' power.

But the point is not to put together a lean, mean fighting machine. It's to take things apart. And to do that you need high energy, at least on a relative scale.

The cathode ray tube in your TV is one of the simplest examples of a particle accelerator (assuming you don't have a flat screen yet). It shoots electrons at your screen, creating colorful images, at about 30,000 eV (30 keV).

Around 1943 the idea of a synchrotron, a circular accelerator that would drive particles using magnets, was proposed. In 1952, the Cosmotron at Brookhaven Lab in Long Island began operations at 3 giga-electron volts (3 GeV or 3x10^9 eV). A handful of other synchrotrons followed, including the 12.5 GeV Zero Gradient Synchrotron (ZGS) which started its operation at the Argonne National Laboratory near Chicago in the early 1960's. Then in the mid 1960's, the SLAC linear accelerator opened in Menlo Park, California, and now accelerates particles up to 50 GeV.

During the 1960's, physicists were seeing new machines begin operations at tens of GeV, but the dreamers had their sights set much, much higher. Plans were being put into action to build a synchrotron that would operate at 1,000 GeV, or 1 tera-electron volt (1 TeV). The accelerator, located at Fermilab, was eventually named the Tevatron, because of this 1 TeV goal.

Reaching 1 TeV was a tremendously long and expensive project and rather than follow the course of the early synchrotrons, which increased their energies by increments of one, two or three GeV, the LHC is now operating at seven times the energy of the next most energetic experiment.
While energy is not the only objective when building accelerators, it is notable what a tremendous leap the LHC will make for high energy physics. We've been pushing on the ceiling of 1 TeV for some time, and the LHC is just blowing the roof off the place, advancing all the way up to 7 times that energy.

But this leap in energy also means there will only be one such machine of this size in the world, and it means there aren't any trial runs. There isn't a 3 TeV machine that LHC scientists can look at to avoid mistakes. It's now or never, and it is truly incredible that everything has gone as well as it has (yes, it has gone well if you consider how wrong it could have gone).

So I say, smashing! Brilliant! Huzzah! This is truly a thrilling thing to see unfold, and I feel fortunate that I am alive to see it happen.

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