On December 18, 2010, just after 6 pm New Zealand time, the last of IceCube’s 86 strings was lowered into the Antarctic ice. Seven austral summers of construction had come to an end, and IceCube was completed a decade after the collaboration submitted the proposal.
Dedicated teams melted 60-centimeter diameter holes to a depth of 2,450 meters, deployed sensors, and commissioned strings from November to February each year from 2004 until 2011. Deployment specialists spent 11 hours on average to expertly connect sensors to a cable and lower them into the water-filled holes, which eventually refroze. In seven seasons, 86 holes in all were drilled and instrumented.
The drill was designed by the IceCube project and built at the UW Physical Sciences Lab. The high-pressure hose and nozzle delivered hot water that melted through the ice at record speeds, about 2 meters per minute, down to depths of 2,450 meters. A separate drill was designed and deployed to advance through the firn layer, the top 50 meters of compacted snow where hot water drilling is not efficient. Together the two drills were able to consistently produce almost perfect vertical holes ready for deployment of instrumentation at a rate of one hole every two days.
Since water starts to freeze immediately, IceCube sensors were quickly deployed following drilling. Once the refreezing process ended, which took a couple of weeks to stabilize, the failure rate of the instrumentation has been extremely low—fewer than 100 of the approximately 5,500 sensors are currently nonoperational.
IceCube sensors, designed with main contributions from Lawrence Berkeley National Laboratory, DESY-Zeuthen, and UW–Madison, were produced and tested at the universities in Stockholm and Uppsala in Sweden, DESY-Zeuthen in Germany, and the Physical Sciences Lab in Stoughton, Wisconsin, USA. Each string of sensors had a general theme, with a name given to each of the deployed sensors as a more effective means of identification rather than a numbering system.
Building IceCube was an extraordinary engineering achievement. It was completed on time, on budget, and significantly exceeding performance specifications. This is a tribute to the perseverance and dedication of the physicists, engineers, and technicians that overcame the many challenges of creating and operating a detector in such an inhospitable environment.
The total cost of construction was $279 million. The National Science Foundation provided around $242 million with the remaining funds coming from funding agencies in the US and abroad.
Read about how the detector works.