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Constance Walter

Starting at 4:01 a.m. on Oct. 6, SNO traffic was pretty heavy. SNO as in Sudbury Neutrino Observatory experiment. And Jaret Heise, Science Director at Sanford Lab, wasn't surprised. Arthur McDonald, who lead the SNO experiment in Canada, had been awarded a share of the 2015 Nobel Prize in Physics for his discovery of neutrino oscillations.  

"We'd always hoped that SNO would win given the unique nature of the experiment," Heise said. "I was pretty excited."

As well he should be. Heise was a Ph.D. student with the University of British Columbia in 1996 when he began working at SNO, a neutrino laboratory located in a Sudbury, Ont., nickel mine. Not a lot of scientists start their day by taking a cage ride 6,800 feet underground where they take a shower before dressing in cleanroom garb. "It was amazing," he said. 

Heise's graduate work involved understanding SNO's sensitivity to supernova neutrinos. He was also part of SNEWS (Supernova Early Warning System), a project designed to give advance warnings to astronomers. 

"I spent a lot of time looking for neutrinos, but unfortunately we never saw a supernova," he said.

Heise worked with SNO for more than a decade, beginning with the inner vessel for the detector and eventually becoming the onsite detector manager. He will share his experiences about working on the Nobel-winning experiment and how it relates to past and future experiments at Sanford Lab on the first Nobel Day, Thursday, Dec. 10. 

The SNO detector included a 40-foot diameter spherical acrylic vessel (AV) that had to be taken underground in pieces then reassembled using an acrylic polymer. The AV was filled with 1,000 metric tons of heavy water (D2O), which contains deuterium, a hydrogen isotope that has an extra neutron. Normal water  (H2O) contains two hydrogen atoms and one oxygen atom. In the final phase of the experiment, the AV also contained an array of nickel tubes filled with helium-3 gas. Incoming neutrinos of all types can break up the deuteron, which is why the heavy water was perfect for detecting neutrino oscillations. 

The discovery proved Ray Davis's solar neutrino experiment calculations were right and earned him a share of the Nobel Prize in Physics in 2002. This year, SNO takes its place among the great experiments in physics history.

"The Nobel really validates all of the hard work that went into building SNO and extracting the evidence for neutrino oscillation," Heise said. "Beyond that, it endorses the science we support at Sanford Lab: further exploration of the properties of neutrinos with the Majorana Demonstrator project, and  trying to understand how stars work through the CASPAR accelerator. Because that's really what Ray Davis set out to do: measure neutrinos and test how the sun works."