Francis Halzen was awarded the 2026 Nobel Prize in Physics, for IceCube!

 IceCube PI Francis Halzen, professor of physics at the University of Wisconsin, Madison has been awarded the 2026 Nobel Prize in Physics, for "“for decisive contributions to the IceCube Neutrino Observatory and the discovery of high-energy neutrinos of astrophysical origin.”  Francis has been a tireless advocate for IceCube, starting in the 1990's, when the idea of a large ice-based neutrino detector was really a laughing matter; few people took it seriously.   This was a simple matter: convince his fellow physicists, numerous committee and funding agencies that the idea was practical, gather one collaboration to produce a proof-of-principle: AMANDA, and a larger one that could be an industrial-scale experiment like IceCube.  Although Francis was not an experimentalist, he was able to bring together a diverse group of scientist, engineers and computer scientists with the necessary skills. IceCube required two key technical development.

The first was drilling deep holes in the ice.  This was most efficiently done using hot water to melt a hole down through the ice, but IceCube required far higher drilling capacity than any previous experiment.  This required a new drill, the development of which often seemed more akin to oil prospecting than astrophysics.   UW Madison and its Physical Sciences Laboratory were responsible for the drilling.  

 

 The second problem was a data readout that would preserve the details (time structure and amplitude) of the light pulses.  Most of this problem fell to Lawrence Berkeley National Laboratory.   The solution was to put the analog and digitizing electronics in the ice, attached to the photo-multiplier tubes, and send slow digital data to the surface.  The challenges here involved reliability (since the modules would be inaccessible after deployment), low-power operation, and a very wide temperature range, down to -55 degrees C.  In essence, we needed to build 5,160 satellites, but with a fraction of the budget that NASA had.  The required tradeoffs made for many interesting discussions, but the result was outstanding; over 98% of the optical modules are still working, with many having spent 20 years in the ice. 

 The final (and perhaps largest) challenge was funding.  Even after construction was approved, there were many people who were skeptical of (a) whether the IceCube detector would work, or (b) whether we would see anything.  Francis deserves enormous credit for convincing the NSF to fund IceCube, and the NSF deserves enormous credit for listening and taking what must surely have been seen as a risk.  We are all better off for it.