Inside the supernova machine
Posted: Friday, January 04, 2008 6:11 AM by Alan Boyle
TRIUMF |
A suit-clad technician kneels inside the 59-foot-diameter TRIUMF cyclotron during a
maintenance session. The particle accelerator is the world's biggest cyclotron.
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In this age of bigger, newer, more powerful mega-machines for particle physics, Canada's 33-year-old TRIUMF cyclotron is literally a blast from the past. Sure, it's the world's biggest cyclotron - but to some physicists that might sound a bit like gushing over the world's most advanced horse and buggy.
In terms of size and sheer power, TRIUMF's 59-foot-wide magnet is dwarfed by Europe's 5.3-mile-wide Large Hadron Collider. When it gets up and running this year, that super-duper-collider will pack a punch 28,000 times greater than TRIUMF's. Nevertheless, there are some things being done at the TRIUMF lab, next to the University of British Columbia's Pacific coast campus, that the bigger places just won't do - such as figuring out how one element turns into another inside an exploding star.
The newfangled big-bang machines in Europe and the United States may grab more of the headlines, based on what may or may not be found in the future - but in the meantime, Canada's 33-year-old supernova machine is working virtually 24/7 on its own assortment of cosmic mysteries.
TRIUMF stands for "Tri-University Meson Facility," but today the consortium actually takes in six Canadian universities, with most of the facility's roughly $60 million in annual funding provided by Canada's National Research Council.
Alan Boyle / msnbc.com
Researchers monitor TRIUMF's operations from a control room, making sure that
the cyclotron and beamlines are working right. "Mostly the training is 'on the job,'"
says physicist Des Ramsay. Click on the image for a larger version.
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Hundreds of students and other visitors troop through TRIUMF every year - and I got my turn during a November trip to UBC, along with about a dozen researchers and journalists. At least one researcher remembered seeing the place as a high-school student. The cool stuff began right in the reception building, where a cloud chamber is set up behind curtains in a corner.
We took turns looking down through the glass at a dimly illuminated tabletop-sized tank, filled with what looked like a dark liquid. If you catch the light just right, you can see little lines and curlicues being drawn in the air beneath the glass.
"There's a little layer of supersaturated alcohol vapor - it's like this is a refrigerator," our tour guide, University of Manitoba physicist Des Ramsay, told us. "When cosmic rays come through, they leave tracks, like a contrail from an airplane. Occasionally a muon will hit a nucleus in there and knock off an alpha or some heavy, densely ionizing particle, so you see a short, fat track. And sometimes you'll see a track that curls around a lot, which is probably an electron."
This video clip gives you the idea - and making a cloud chamber is actually something you can try at home, assuming you're handy with dry ice, pure isopropyl alcohol and the home-brew construction supplies.
One thing you shouldn't try at home is building a cyclotron, which involves sending a beam of charged particles around a matched pair of D-shaped magnets, each as big as a backyard patio. The particle beam spirals from the center to the outside of the cyclotron, picking up energy every time it crosses the gap between the "dee" magnets.
It's impossible to ramp up the particles to the energies achievable in the ring-shaped Tevatron at Fermilab in Illinois, or at CERN's Large Hadron Collider on the French-Swiss border. But you can get a steady, high-intensity beam at just the right energy for what you're looking for. In fact, you can get several different beams at different energies simultaneously - which is something you just can't do at the Large Hadron Collider.
Alan Boyle / msnbc.com |
Paper clips stand up straight on the top of a glass
case three stories directly above the TRIUMF
cyclotron, due to the device's strong magnetic field.
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We weren't allowed to see the cyclotron itself, but we could feel its presence as we stood on a concrete slab three stories above the magnets. Even that far away, with all the shielding between us and the device, the magnetic field is strong enough to make paper clips stand on end - which is the coolest magic trick on the TRIUMF tour.
Once the accelerated protons leave the cyclotron, smaller magnets guide the beam to a variety of destinations. The principal destination is another facility called the Isotope Separator and Accelerator, or ISAC. The protons blast away at a target, creating a rainbow of radioactive isotopes. The isotopes of interest - for instance, potassium-37 - are separated out from the collisions, and those precious particles are accelerated into yet another high-energy beam.
"This is the home of the exploding-star people," Ramsay told us.
The exploding-star people on TRIUMF's DRAGON research team select short-lived isotopes that are thought to exist naturally only inside a star, and smash them into hydrogen or helium nuclei. The results shed additional light on the primordial nuclear reactions that gave rise to the heavier elements we see on Earth today - including the elements needed for life as we know it.
One of TRIUMF's triumphs was to study how smashing together a proton and sodium-21 can produce magnesium-22 and release gamma rays in the process. That's just the kind of reaction that may have taken place eons ago in supernovae. Similar studies have been conducted to trace the transmutation of aluminum isotopes into silicon, then into sulfur, argon and calcium, and at last into titanium.
Such isotopes of all those elements can serve as the "fingerprints" for exploding stars - including the primordial supernova that souped up our own cosmic neighborhood.
TRIUMF |
The worker at the center of this picture is dwarfed by the
hardware and concrete shielding in TRIUMF's Meson Hall.
Click on the picture for a larger view.
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TRIUMF's beams produce more down-to-earth benefits as well: One beam is directed to the Proton Irradiation Facility, where satellite components can be tested for radiation sensitivity.
The BC Cancer Agency also uses the beam to treat eye cancer: More than 100 patients have received proton-beam therapy - including blogger Robert Lee, who is documenting his battle against cancer on MyOcularMelanoma.com.
Among TRIUMF's other medical products are radioactive isotopes for medical treatments and imaging - products that go to a Canadian company named MDS Nordion in exchange for royalties.
"They play our 'tune,' and they pay us every time they play it," Ramsay said. During 2006-07, MDS Nordion paid TRIUMF about $828,000 for those radioactive tunes.
Researchers from TRIUMF also harmonize with other physicists around the world - even at the Large Hadron Collider, which incorporates kicker magnets contributed by Canada. TRIUMF also provided the end-cap calorimeters for the ATLAS detector at the Large Hadron Collider, and will serve as one of the main data distribution centers for the ATLAS experiment.
Alan Boyle / msnbc.com |
Physicist Des Ramsay checks his dosimeter at the
end of our tour of the TRIUMF particle physics lab.
Good news: We weren't exposed to any extra
radiation during our visit.
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Someday, ATLAS may pick up the first evidence of the Higgs boson, an elusive subatomic particle that is thought to be responsible for giving other particles their mass. "The first guys who see it probably will get a Nobel Prize," Ramsay told us.
So even though the big news in physics will likely be coming from elsewhere for the next few years, TRIUMF will be sharing in the Large Hadron Collider's glories, as well as celebrating its own scientific triumphs back home in Vancouver. It all goes to show that although there may be rivalries in the race to solve physics' greatest puzzles, scientists around the world - at TRIUMF and at Fermilab as well as at CERN - are all really on the same team.
Update for 1:10 a.m. ET Jan. 23: I originally wrote that MDS Nordion paid about $4.5 million to TRIUMF in 2006 for radioisotopes, based on a line in that year's financial review for the lab. But the folks at TRIUMF tell me the actual royalty figures are a bit lower: $1.3 million for 2005-06, and $828,000 for 2006-07. My guess is that the financial review takes in other payments, or accounts for the funding in a different way. In any case, I've revised the item to reflect the lower figure.
More dispatches from the Big Science Tour:
