SNOLAB
If you want to see pictures from my tour, skip to the last section of this blog. The other sections will provide the history of SNOLAB and current experiments.
History of SNOLAB
SNOLAB began as a single neutrino* observatory, called the Sudbury Neutrino Observatory (SNO), in May 1999. The first scientific results were published in 2001, and in November 2005, the original SNO detector was turned off while the data from the experiment was analyzed (this data supported the original results published in 2001).
*A neutrino is a subatomic particle, like an electron. However, unlike the electron, neutrinos are electrically neutral (electrons are negatively charged).
In 2002, the Canada Foundation for Innovation approved funding to expand the SNO facilities into a permanent, general-purpose facility. Construction of the major laboratory space was completed in 2009, with the entire lab entering operation as a clean space in March 2011. |
The director of the original SNO experiment, Art McDonald, was co-awarded the Nobel Prize in Physics in 2015. He is the one who insisted the new permanent facility be called SNOLAB, in honor of the original SNO project.
Besides neutrinos, SNOLAB is most well known for its experiments on dark matter. Dark matter is a theory scientists use to explain how large objects move in space, like the rotation of galaxies and individual planets. Basically, dark matter is a cosmic glue that holds everything together and provides additional mass to the universe, but we cannot see it or detect it.
Since the very beginning of the 1900s, scientists tossed around the theory of dark matter, but it wasn’t until 1978 that scientists took the theory seriously, when two scientists showed how well dark matter made the mathematical equations work.
At SNOLAB, there are currently four ongoing dark matter experiments, with more in the works.
DAMIC DAMIC stands for Dark Matter in CCDs. A CCD is a charge coupled device, or a device that uses electrical charge to create pictures. Essentially, when a photon (a light particle) passes through a CCD, it collides with the electrons in the device’s silicon sensors. This causes the negatively-charged electrons to move slightly, alerting the sensor to a change in the electric charge at that point. The sensor sends this information to a computer, which creates a picture showing where and how much movement occurred in the sensor. In the DAMIC experiment, instead of looking for photons, the sensors are tuned to look for theorized dark matter particles. | Our tour guide, Blaire Flynn, stands next to DAMIC. It is a bit boring to look at since we cannot see inside the detector. |
PICO-60 (formerly called COUPP-60) PICO-60 is what is known as a bubble chamber detector. A bubble chamber detector is a vessel filled with a superheated transparent liquid (most often liquid hydrogen) used to detect electrically charged particles moving through it. Instead of liquid hydrogen, though, PICO-60 uses octafluoropropane (C3F8). I like the purplish-lighting inside PICO-60, makes it look super cool! |
DEAP-3600 and MiniCLEAN DEAP-3600 gets its name from the fact the detector uses 3,600 kg (7,940 lbs) of liquid argon. The idea is that low-energy interactions will cause ripples in the liquid argon. If we tell the computer to ignore all the ripples that come from interactions we are already familiar with, then we can focus on the ripples that cannot be immediately explained. If all goes well, these unexplained ripples will be caused by dark matter. Along with DEAP-3600 is a detector called MiniCLEAN, which uses only 500 kg (1,100 lbs) of liquid argon. Both follow the same general idea for detecting dark matter, with a few differences in their specific approaches. | You can see DEAP-3600 in this photo. MiniCLEAN was sitting to the right, offscreen. |
SuperCDMS and CUTE SuperCDMS stands for Super Cryogenic Dark Matter Search. This experiment will use superconducting thin films to detect interactions, much like the DAMIC experiment. However, unlike DAMIC, SuperCDMS uses both silicon and germanium in its sensors to increase accuracy of interpretation of observed signals (DAMIC uses only silicon). CUTE stands for Cryogenic Underground TEst facility. CUTE is being installed in advance of SuperCDMS, to do performance tests, calibrations and background measurements in support and preparation for SuperCDMS. Top: The tape on the floor marks where SuperCDMS will be built Below: We are inside CUTE |
Ever since general relativity came on the scene in 1915, scientists have used that theory to successfully explain many phenomena. Thus, it makes sense why scientists are so resistant to considering alternative theories that would cast general relativity aside. Plus, everyone just loves Einstein and don’t want to question one of their scientific heroes. :P
Usually the science communication students tour SNOLAB in November, but with the craziness of this being the first year of the full master’s program, scheduling a tour happened a bit late. Because of this (and the fact we had to get there by 7 a.m.), only four of the 13 students went. But having a smaller group worked well!
SNOLAB is accessed through the Creighton Mine, which is owned by Vale. We didn't take any photos until we reached SNOLAB, as a courtesy to the miners working there.
Left: A replica of what SNO+ looks like. The inner ball is filled with liquid scintillator.
Right: A tour guide poses with one of the outer-layer platings of SNO+
During the tour, Blaire told us that every Friday is fire alarm testing day. As luck would have it, I happened to be recording just as the testing started.