Enormous 1km ice-cube machine fashioned at South Pole
Boffins in magnificent Futurama style feat
International boffins have created an enormous particle detector by instrumenting up a kilometre-on-a-side cube of the utterly pure and transparent ice found thousands of metres beneath the surface at the South Pole.
Sensibly enough the boffins left the giant ice cube in place rather than trying to move it to somewhere more convenient. Sensitive optical instruments were lowered down holes drilled into the ice cap to depths of as much as 2,450m. Sealed up in the transparent darkness kilometres below the Amundsen-Scott South Pole Station, the sensors are able to pick up tiny flashes of blue light ("Cherenkov radiation") produced when a neutrino collides with a particle amid the ice.
Such neutrino interactions are extremely rare - most neutrinos pass right through the Earth without stopping. That's why the Ice Cube sensor needs to be so big, and why it needs to be located deep down in the dark where nothing else is going on and the tiny Cherenkov flashes can be seen.
Neutrinos are generated in the Sun and by cosmic-ray impacts and other high-energy sources. As they aren't affected by anything much once they've been generated, scientists believe that a working neutrino sensor will be able to find out a lot of important things about the universe around us. That's why it was thought worthwhile to spend no less than $279m (mostly from the US National Science Foundation) to build the Ice Cube.
That building was no simple matter. Just getting to Antarctica is fairly troublesome, and after that the materiel and people to make the Ice Cube had to be shipped 800 miles from the main US base at McMurdo Sound to the Amundsen-Scott base at the Pole itself. This has to be done using specially modified C-130 Hercules military transport planes fitted with skis (and often using rocket-assisted takeoff, pictured on the next page). The Amundsen-Scott surface base installation had to be built mounted on powered stilts in order to lift itself out of snow which would otherwise periodically bury it.
Meet the rocket ski-plane and the ice drill as powerful as a locomotive
Rocket ski-plane - a bit easier than dog sleds
Once at the Pole, the boffins needed to drill holes more than 2km down into the ice. This was done with a tool specially invented for the job: the Enhanced Hot Water Drill, developed in the physical-sciences labs of the University of Wisconsin-Madison. The mighty ice drill, rated at no less than 4.8 megawatts (this is a drill as powerful as a railway locomotive) can bore through a kilometre of ice every day, so allowing the long sensor cables to be lowered into position.
As of December 18th, according to the NSF, the mighty Ice Cube was finally complete.
"IceCube is not only a magnificent observatory for fundamental astrophysical research, it is the kind of ambitious science that can only be attempted through the cooperation - the science diplomacy, if you will - of many nations working together in the finest traditions of Antarctic science toward a single goal," said Karl A Erb, director of NSF's Office of Polar Programs.
Down into the vast, transparent darkness
The Ice Cube was funded by the US, Belgium, Germany and Sweden. Barbados, Canada, Japan, New Zealand, Switzerland and the UK will also join in the IceCube Collaboration which will analyse the resulting data.
More accurately, one should say, they are analysing it and have been for some time: the Ice Cube actually went into operation well before being finished. The first data were produced in 2005.
"With the completion of IceCube, we are on our way to reaching a level of sensitivity that may allow us to see neutrinos from sources beyond the sun," says Francis Halzen, top boffin on the project.
There's more on the mighty Ice Cube here. ®