Page 3/3 - Posted December 4, 2009
IceCube already proving worth with experiments of opportunity
In the end, only one company in the world, in Italy, had the expertise to build a hose for that drill. The Physical Sciences Laboratory at the University of Wisconsin-Madison built the drill itself.
“It’s exciting working on a practical problem like this when you spent your life working on particle physics,” Halzen adds. That was another hurdle in convincing the NSF and peers that the project could work. Some balked at putting a theoretician in control of such an unwieldy experiment. Halzen admits he had his own doubts.
“It’s the biggest project ever done out of a university. In fact, a lot of people thought we couldn’t do it.
“They thought I was crazy. Who can blame them? … I was actually looking for someone who could actually do this,” he recalls. A mathematician turned theoretical physicist — this was the 1960s and the thing to do at the time — Halzen says today he would have gone into cosmology.
“I always thought it was much more exciting to do the experiment than theoretical work,” he says, “so it’s not a total accident that I am sitting here today. … What I didn’t anticipate is that here I am sitting 20 years later doing it. My intention was always to hand this off to somebody else. That somehow never happened.”
The smartest thing he did, Halzen says, was hire the right people to manage the project on the ground. “That’s why this project has succeeded,” he notes. Two years into the project, a new project director, Jim Yeck, was hired. “When I say that the smartest thing I did was hiring the right people I was mostly thinking of that position.”
The big discoveries — finding the origins of cosmic rays or of dark matter, the latter more of a European fetish — are still ahead. But that doesn’t mean IceCube hasn’t already proven its worth in other unexpected ways.
“You really build these experiments to have surprises. The real surprise we got was that someone plotted the sky with IceCube. Not through the Earth, which is what we typically do with neutrinos, but looking from above,” Halzen says.
There are also projects of opportunity with IceCube. Some researchers have done glaciology with the detector, sending down an instrument to measure the concentration of dust and other particles frozen in the ice. This is the sort of work normally reserved for ice cores.
“We can see the dust of individual volcanoes. We have mapped the ice impurity with better resolution than people have done with cores,” Halzen says.
Then there’s the fact that scientists have instrumented a cubic kilometer of ice, something no one has ever done. The ice sheet moves about 10 meters per year. How does the flow rate change with depth? “It flows pretty uniformly, so it is the small deviations that we’re trying to measure,” Halzen says.
The galaxy itself may provide a different opportunity not too far into the future. Scientists predict a supernova explosion occurs once every 30 years. Such a stellar explosion, which can radiate as much energy as the sun could emit over its entire lifetime, would justify the existence of IceCube in about 10 seconds, Halzen enthuses.
“If we now had a supernova explosion in our galaxy, we would measure it with incredible precision,” he says, the words almost a purr of intellectual satisfaction.
What would scientists learn about such an event? Many things: The neutrinos would record information about the explosion itself, as well as how stars collapse and explode. What’s left behind in the debris is a neutron star or black hole.
“The neutrino basically sends you a movie of what’s happening,” Halzen says.
The experiment is designed to last 20 years or more, and the last supernova occurred in 1987, so there is an excellent chance IceCube will be around with a front row seat to that rare show.
In the meantime, while waiting for those small moments of opportunity made possible by big science, Halzen and his team of scientists, engineers, technicians and drillers will continue to bore into the Antarctic ice sheet. Completion is a foregone conclusion. Difficulties working in the world’s harshest environment are a foregone fact.
“I have no idea how boring it will be once all the construction is over,” Halzen says.