International Polar Year Antarctic Blog
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IceTop Milestone!
International Polar Year link11:15 a.m., Dec. 6, 2007--Editor's note: Over the next few weeks, with support from the National Science Foundation, a team of University of Delaware researchers will be at work in one of the iciest, coldest, most austere places on the planet: South Pole, Antarctica. Currently stationed at the South Pole are UD researchers Thomas Gaisser, Stoyan Stoyanov, and James Roth of UD’s Bartol Research Institute, who are working on the IceCube neutrino telescope.

Their Antarctic blogs will appear on UDaily and on the Wilmington News Journal’s Delaware Online Web site through a partnership between UD and the newspaper.

Most of you have read about IceCube or IceTop earlier in this series. For those who haven’t, we are building the world’s largest Neutrino Telescope here at the South Pole. Neutrinos are incredibly hard-to-detect particles, so we need a really big detector. IceCube, when finished, will use a cubic kilometer of South Pole ice to capture the light signal left by neutrinos that have passed entirely through the Earth. Neutrinos point directly back to their source, so they will help us map the Northern sky in ways that have never been seen before. 

IceTop is the surface array of the IceCube Project. IceTop helps IceCube to find the neutrinos that have passed through the Earth by filtering out the cosmic ray particles that enter the Southern atmosphere. IceTop uses tanks of perfectly clear ice to detect these cosmic ray particles that enter the atmosphere above it.

It sounds easy to make ice at the South Pole, but everything at -40°F is a challenge. In order to make clear ice, we must control the freezing process. We need to remove the dissolved gases from the water to avoid cloudy bubbles, and we must allow for the expansion of freezing water to avoid cracks. We have, in previous seasons, produced 52 of the 160 tanks of clear ice required to complete the project. This year we will add 28 new tanks to the array.

The process, here at the Pole, is to dig a trench for two IceTop tanks. We then place the tanks in the trenches. Surface cables supply power and communications from the central IceCube lab to the trenches. Freeze Control Units (FCUs) are installed at each tank, and the tanks are filled with filtered Antarctic water supplied by the IceCube hot-water drill.  The FCUs do their job to produce a 1 meter deep by 2 meter diameter block of clear ice with two detector modules in each tank.

Yesterday, Dec. 5th, we prepared the first two IceTop tanks for filling. This is a milestone for us! It has taken Tom Gaisser, Stoyan Stoyanov, and me nearly a month to prepare for this moment. Today, we will fill the first two tanks and the process will continue each day until the 28 tanks are filled. We will closely monitor the freezing process for the minimum 40 days required to freeze each of the 650-gallon IceTop tanks.

--James Roth, UD Antarctic Research Team