Summer 2010

Francis Halzen pictureProfessor Francis Halzen is the Principal Investigator and co-spokesperson for the IceCube Project.  He is a Hilldale and Gregory Breit Professor at the University of Wisconsin-Madison.

Professor Halzen took time out of his busy schedule to contribute the following article on the importance of the collaboration between IceCube and PSL. 

At the end of a recent PSL staff meeting, members of the IceCube project presented PSL with a plaque thanking them for the completion of the Stoughton phase of the project.  Although I don’t remember exactly what the plaque said, I do remember that I found it somewhat inadequate to reflect the pivotal role PSL played in the project.  The mission was clearly defined in the 1999 proposal to the NSF: deploy 60 digital optical modules between 1500 and 2500 meters in the Antarctic glacier covering the South Pole in less than 2 days; repeat 80 times.  By December 21, we will have done just that.  A cube of ultra-transparent Antarctic ice, one kilometer on the side, will have been transformed into the largest particle detector ever built.

A digital optical module is basically a 10 inch photomultiplier attached to a data board that captures and digitizes data and applies a time stamp precise to the nanosecond.  Deploying a module is equivalent to launching a satellite; they have to last 20 years without access once they are frozen into the ice—so far so good.  And then there is the drill.

Built at PSL, the hot water drill melts its way down the ice, delivering water at 88⁰C under pressure from a nozzle supplying 760 liters per minute.  It is fed by a heating plant delivering 4.8 MW.  Like building a ship in a bottle, the drill was disassembled to fit into some fifty C130 cargo planes and reassembled at the South Pole.  In the Antarctic summer of 2005, a million pounds of cargo made its way from PSL to Antarctica and by the completion of the three-month season, string one was ticking like a Swiss watch.

It all started with the call from NSF program officer Gene Loh: “Halzen, sometimes you get what you ask for”.  The IceCube project had been approved and even a Madison theorist knew what to do next—head for Stoughton.  For IceCubers this was even more obvious given the critical role PSL played through the AMANDA project.  AMANDA represented the proof of concept for IceCube, a detector a hundred times bigger.  That AMANDA had convincingly succeeded into validating the technique to build a kilometer-scale neutrino observatory became clear when the project suddenly faced an (essentially unfriendly) takeover by a national laboratory.  That the technique had been pioneered at UW would have meant nothing if PSL could not have been offered as a credible partner.  Without PSL, it is likely that UW-Madison would have lost its status as lead institution and now the center of all operations of the detector.  

Thanks PSL! This is what the plaque did not say.

IceCube Plaque Image

PSL’s legacy will not only live on through IceCube operations, scientists and engineers are busy dreaming up further missions for the hot water drill.  Though immature at the moment, these range from the deployment of low background dark matter detectors in the deep sterile Antarctic ice to the planning for a trip to one of the deep lakes covered by the Antarctic ice shelf.  And when neutrino physicists tackled the design of a neutrino detector for the new underground laboratory in Lead, South Dakota, that will have roughly ten times more photomultipliers than IceCube, they also found the way to Stoughton.

Plaque Presentation
Former PSL Director Dave Huber and current PSL Director Farshid Feyzi accept the plaque.




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