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Reflections on the Nobel Prize in Physics

26 October 2015

News that the Nobel Prize in Physics 2015 was awarded to Takaaki Kajita of the University of Tokyo and Art McDonald of Queen's University sparked a day of celebration at TRIUMF. We spoke with TRIUMF’s Ewart Blackmore, Rich Helmer, Jean-Michel Poutissou, and Reda Tafirout to learn more about the laboratory’s contributions to the SNO experiment and to hear reflections on their colleague, Art McDonald.

Located 2 km below the surface in the Vale Creighton Mine near Sudbury, Ontario, the SNO experiment observed solar neutrinos through their interactions with heavy water in a large underground tank. The SNO experiment was unique in that, for the first time, researchers could measure the total flux of all neutrinos emitted by the sun in a specific reaction irrespective of their initial or final flavor. All previous experiments had assumed that the neutrino kept its original flavor as it travelled towards Earth. The detector was operational from May 1999 until November 2006. The underground facilities have since been expanded to what is now SNOLAB.

“TRIUMF became actively involved in SNO when the project needed engineering help,” explains TRIUMF Researcher Emeritus Rich Helmer. “TRIUMF’s [then] Director Alan Astbury was very supportive and with significant commitment of resources from TRIUMF’s Design Office and Machine Shop, we built two key components (the universal interface and rope equalizers) for the detector. Later, the electronics designed and built at the University of Pennsylvania were all sent to TRUMF for testing. That was a big job and took about a year.”

Reda Tafirout, currently a TRIUMF researcher, was a postdoctoral research associate based in Sudbury from 1998 to 2002 with Laurentian University and made several contributions for the experiment. “I was very fortunate to be part of SNO and experience the evolution of the experiment from its early stages. I was fortunate to have been part of the hard work required to produce remarkable results and solve a 40 year-old solar neutrino puzzle that led to the Nobel Prize,” he says.

Members of the TRIUMF community – including Ewart Blackmore and Jean-Michel Poutissou – supported the collaboration through various peer and oversight committees.

TRIUMF Emeritus Jean-Michel Poutissou recounts, “I first got involved in discussions about the idea of using heavy water as a neutrino detector in 1983.” Jean-Michel chaired the NSERC Committee that reviewed the grant request to drill the hole in the mine and initiate the project, which later recommended proceeding with funding. From 1993 to 1998, he chaired the annual SNO NSERC Review. “I had the added privilege of going to Sudbury every February for a few days of -27 ºC temperature on top and +27 ºC at the bottom of the mine!”

Ewart Blackmore, a long time Division Head at TRIUMF, chaired a review of the SNO experiment in 1992 when both the underground excavation of the hole for the detector was underway and while the SNO team was working on the early design work of the detector components.

“Our review team had the opportunity to visit the mine to see the excavation work and appreciate the challenges of such a large opening at this depth. For example, the rock stresses had to be carefully managed and the future difficulties of keeping the detector clean had to be considered as a few drops of mine dust could cause serious activation problems in the detector. I found it fascinating.”

As the SNO collaboration grew, a new committee was set up called the SNO Agency Review Committee (SNO-ARC). From 1999 to 2007, Ewart was a member of the SNO-ARC and Science Subcommittee.

“I believe our committees helped focus the attention of the collaboration to meet their schedules, to improve the efficiency of data taking and to explain the justification for the timing of the different phases of the experiment. We also helped to move the experiment from a group of university scientists to a project with appropriate infrastructure support and operating personnel,” explains Ewart.

“Although there were a number of senior and very capable scientists on this experiment,” says Ewart, “Art was the obvious leader and he presented the SNO project (status and financials) very clearly. He is a great physicist but also a great leader. He kept the collaboration working hard to meet the scientific goals of the experiment.”

Jean-Michel adds, “Art is a first class nuclear physicist who understood the very demanding requirements of this experiment and never doubted it could be done in Canada. He worked for 10 years to collect the necessary funds to support the experiment. Art is a leader, a motivator and he kept motoring on, driven by this unique opportunity for Canadian science. When others dropped their financial support, NSERC continued their support to SNO, in large part because NSERC uses a peer review system to get advice for funding to ensure it was done successfully.”

“I expect that all of us involved with SNO realized that solving the solar neutrino puzzle was a Nobel Prize winning endeavour,” shares Ewart. “When I heard on the 7AM CBC news, I felt very good for Art and the SNO experiment. It brought back the memories of seeing Art with his cell phone glued to his ear – the picture that has been shown in the news.”

“I was extremely happy for the SNO collaboration, for all of my previous colleagues and especially for Art, who was highly respected by all and truly deserves it,” says Reda.

“Art is very much a team person,” adds Rich. “He wants everyone working with him to be a team. He has won many awards over his career and he puts his prize money back into research, into hiring young students."

“I thought that this was great day for subatomic physics in Canada but also in Japan,” Jean-Michel says, “as it raises the probability that Japan will fund the Hyper-Kamiokande project that Kajita-san and the international community, including Canadian T2K physicists, are promoting to go beyond the Nobel-prizewinning work of Art and Kajita-san.”

“Early on in the experiment,” says Rich, “Art asked me to fill in for one of the SNO Associate Directors who was unable to get to Sudbury for a couple of months. Later, I returned to Sudbury to act as Commissioning Manager. During those periods I shared an apartment with Art. One day he was expecting to have a bit of a tough time as he was going to have to deal with some human resources issues as well as meet with lawyers to sort out a legal issue to do with the lab - not the sort of things physicists normally do in a day. He turned to me at breakfast and said, ‘They say this is supposed to be fun!’ I'm sure winning a Nobel Prize makes up for any tough times!”

While it’s clear that the TRIUMF team has many warm recollections of their involvement with the SNO experiment and their experience working with Art, Art welcomed TRIUMF’s involvement in the collaboration. "I have many fond memories of my colleagues tremendous contributions, as well as the strong support that we have received from TRIUMF throughout,” says Art.

-Melissa Baluk, Communications Coordinator