Two kilometres underground to a thousand light years away: a trip to SNOLAB

One of the most interesting facets of my job as principal is exploring the myriad different kinds of research and scholarship that occurs on our campus–or off it. To start an intermittent series of blogs on some of these activities, I’ve chosen one of our best known (at least in scientific communities), SNOLAB. Funded by the Canada Foundation for Innovation, the various institutional partners, and other provincial and federal granting agencies, it is among the most ambitious ‘Big Science’ projects undertaken in Canada.

schematic of SNOLAB; pinecone shaped area at bottom left is that occupied by original SNO experiment

SNO stands for ‘Sudbury Neutrino Observatory’ and is the name of a particular experiment, years in the making, the purpose of which was to detect and study neutrinos. These subatomic particles are emitted by the sun, and further away, by super-novas. And, according to Prof Tony Noble of Queen’s Physics Department, they come in 3 ‘flavours’. A burst from a supernova will actually precede optical sighting of the supernova, so a detection will, we were told on our visit, immediately cause lots and lots of telescopes around the world to be trained in that direction to observe the event of which the neutrinos are the herald. Neutrinos are not caught like butterflies or herring. In order to filter out all the background radiation that they are surrounded with, it is necessary to be either inside a mountain, or far underground, since the other forms of radiation do not travel as well or efficiently. The earth provides a filter and the detector itself, a big round ball full of heavy water, provided the sieve to catch the neutrinos. SNO was the brainchild of Dr Art McDonald, also of the Physics Dept. It was constructed nearly 2 km down a vertical mineshaft. This is located just outside of Sudbury, on the site of Vale Mines (formerly Inco) local operation. Queen’s owns the land on which the new surface building (which houses offices and rooms for prepping those going to the lab proper, but the project as a whole is a shared initiative between five universities: Queen’s, Carleton, Laurentian, U de Montreal, and the University of Alberta. It is affiliated with other major particle physics endeavours in Canada, notably the Perimeter Institute, and TRIUMF (the national particle research facility based at UBC but also involving several university partners, Queen’s among them). The success of the original SNO led to the idea of expanding the facility (both literally in size and also in scope of inquiry) into SNOLAB, which is bigger by several orders of magnitude than the space occupied by the original SNO. The original experiment has now been concluded (though it is being succeeded by a ‘SNO Plus’). It has a complicated governance structure atop which sits the SNOLAB Institute, which provides more or less the same level of oversight to the SNOLAB management and scientific teams that the Queen’s Board of Trustees provides the administration. Vice-Principal (Research) Steven Liss and I, along with Director of Public and Government Affairs Sheilagh Dunn, paid a visit to SNOLAB on August 24. The lab isn’t quite complete but already has some new experiments going. Just getting to the lab is an adventure. As a kid (and even more recently) I always enjoyed science fiction films; the depth of SNOLAB and the stages one goes through reminds me of the 1971 film The Andromeda Strain and its ‘Wildfire’ facility (based on Michael Crichton’s first novel). In a nutshell, here are the steps: First, you have to arrive the day before in Sudbury. We did so, and had a dinner meeting with my friend and colleague Laurentian University President Dominic Giroux and a number of his administrative team, in conjunction with Prof Noble, who commutes between Kingston and Sudbury. The next morning we had to be out of the hotel by 615. We were driven to the surface building of SNO where we deposited wallets, cellphones (not allowed in the mine!) etc and donned mining gear–rough coveralls, socks, rubber boots and a miner’s helmet complete with headlamp. Then we were marched over to the minehead, signed in and  were each given a tag, which we then hung on a pegboard to indicate we would be down the shaft.

getting ready to descend

At 740 we were called to the ‘cage’ as the elevator that takes people up and down the various levels of the mine is called. It’s a tight squeeze on one of the cage’s two decks. A series of buzzes signalling to the cage operator, and we were on our way down at a pretty brisk rate of descent not unlike landing in an airplane. At the bottom, we were disgorged from the cage. But at that point we were still 2 km horizontally from SNOLAB which is right at the end of a long tunnel known as the drift. Our helmets now lit, we proceeded through the mud and water down the tracks to the lab door. (Because the cage and drift are Vale property, we couldn’t take photos of this part of the adventure). There our boots were washed off and we went through the first of several doors.

just inside the lab

Once inside, everyone was separated into male and female change rooms. We discarded our mining outfits (hanging them up for exit later in the day) and took a shower. We then put on clean gear including finer coveralls, new inside boots, a hairnet, and another hardhat for walking through the internal tunnels. The whole process from getting to the cage to being fully clean and inside the lab took about an hour. We had a number of excellent guides on our tour. Samantha Kuula is a fulltime SNOLab staffer charged with outreach and communications. She makes the trip down at least a couple of times a week either with groups or to reconnect with the science going on so she can write about it. Tony Noble, Director of the SNOLAB Institute (and a former director of the facility itself) was of course with us, and Dr Nigel Smith, a British physicist who is the SNOLAB Facility Director and Dr Fraser Duncan Associate Director. Nigel, Tony and Fraser took it in turns describing the innards of the original SNO site and the expanded SNOLAB, while Samantha was responsible for getting us in and out. I was also pleased to see on the trip down a 3rd year Engineering Physics student, Kira, who has spent the summer building a cooling unit for one of the experiments. She was there to try it out.

in the central kitchen; that's me with the coffee

After a brief rest period for some coffee and fruit and muffins (which has to come in double bagged to be clean, and can’t go out again except in special garbage containers), we were ready to begin the walk around the facility. We saw first the site of the original SNO experiment, in one of several big holes carved out for the purpose. The SNO site is a bit cramped, with low ceilings and tight corners (needless to say just about everything that comes down the shaft has to fit in the cage and often be reassembled underground). Once done there, and after another break (the air pressure is higher down underground and one can tire easily), we were off to see the new facility. Well, if getting into the lab reminded me of the Andromeda Strain, the lab itself seems more like one of Ernst Blofeld’s hideaways in an early James Bond film, minus the armed henchmen. I almost expected to see a white cat. The internal tunnels (there are no square walls or ceilings) have been trowelled down to a flat finish in order to reduce the dust (one or two service lines have a rougher, stucco finish). Everywhere are uniformed workers with hardhats, either on one of the experiments, or completing some of the infrastructure. Crews work 4 10 hour shifts a week. Our tour was there for a little less time as we were scheduled to go back up on the 2 pm cage.

getting an overview of SNO

The facility, as mentioned, isn’t quite complete, but it already has ‘tenants’. SNOLAB is, if you like, a kind of hotel for big science projects requiring underground siting. Several of these, such as SNOPlus and DEAP (an experiment to search for ‘dark matter’ using liquid argon–the acronym stands for “Dark Matter Experiment using Argon Pulse-shape discrimination”) have Queen’s faculty as the principal investigators, others involve two or more of the partner institutions. But SNOLAB is an open facility in the sense that scientists elsewhere can apply to set up their experiment within SNOLAB for a period of years, and then vacate when their research has run its course. They bring their own funding (some of it American for instance), but there is a huge advantage in not having to replicate the clean rooms and basic infrastructure that the lab as a whole can provide. Some of the experiments are looking at very similar problems, but using different methods.

HALO, one of the SNOLAB experiments (nothing to do with the video game of the same name!)

And some of them are small pilots for bigger experiments to come–smaller scale machinery are set up to demonstrate that the experiment can in practice work before a major outlay for larger scale facilities is needed. Thus DEAP will soon be moving to its full-scale version from the working pilot. As a  historian, I have very limited knowledge of the science behind all these experiments, so it was great to have Tony, Nigel and Fraser explain them in lay terms. What most impresses one is the sheer scope of the planning that has to go into simply setting up any of these experiments, never mind executing them, and also the long term investment of time–these are not experiments that generate an instant return of published papers.

outside a couple of grain silos adapted for experimental purposes

Such productivity can take several years (though a relatively short span compared to the length of time that the neutrinos and other particles have been travelling to our part of the galaxy!)

interior of the silo, looking up; all of the equipment must be brought down in the cage and reassembled in the lab

At 1 o’clock we wrapped up, went back to the kitchen for a final rest period, then reversed our steps, abandoning our labwear for our mining togs once again, back along the drift and up the cage. Once back at the top of the shaft, we removed our tags from the pegboard and signed out of the mine. Then, back in the SNOLAB surface building, we reshowered to get the mine grime off again, and got back into our street clothes. It was an extraordinary experience, but amazing as the facility is, the experiments that will live in it for the next 3 or 4 decades (or until the mine closes) promise to be even more fascinating. And it all takes place right here in Canada, with Queen’s University as a leader.

All photos by S. Liss and S. Dunn

Some relevant links: SNOLAB home page http://www.snolab.ca/ Queen’s Particle Astrophysics projects http://www.sno.phy.queensu.ca/group/projects.html

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