Thursday, December 14, 2017

Day 4 SNOLAB Research Experience -- Friday, December 14

This is what they call the Cryopit --  it is the deepest, cleanest underground cavern of its size in the world.  It will eventually house an experiment that requires super cold, cryogenic temperatures.  15 meters wide and almost 20 meters high!

It is my last day at SNOLAB -- what can I say --  it has been amazing!!  The best thing about being here so many days in a row is getting the opportunity to understand so many things.  As I look back on my notes from Monday, it all makes so much more sense.  My tour guide, Blaire Flynn, and all of the employees have made me feel welcome and have willingly shared their knowledge and experience.  I am so grateful for this opportunity!  I would also like to take this opportunity to than the Canadian Association of Physicists for funding this trip of a lifetime!!

One discussion we had here today is the necessity of failure to the process of science.  That is right -- I said failure!  When you think about it, all of the experiments so far have not detected dark matter.  Trial and error -- arguing and compromising -- throwing out and starting over -- all of this has been in the stories I have heard this week.  

To be a true scientist, you must be comfortable with failing and starting over again.  But that is easier to do when you truly understand the necessity of it!!

The DEAP experiment was our main focus today.  It uses three and a half metric tons of cryo-cooled Argon inside it's acrylic vessel to try to detect Dark Matter.  The temperature of the Argon is about -180 degrees celcius.  Brrr.

It contains about 250 photo-multipliers (PMTs) that use the photoelectric effect to detect even the smallest amount of light.  When an event occurs in the Argon it emits a tiny amount of light -- sometimes as little as one Photon.  An event could consist of the Argon interacting with a muon, an alpha particle, a neutron -- and ultimately -- the pièce de résistance -- a (particle of) dark matter.

DEAP  has been running since 2016 and will run about another three years.  Students and Post-doctoral students are the individuals who usually analyze the data.  However, there are many events happening all the time, but software (much of it designed and programmed by the physicists themselves)  will weed out the 99% of known events.  The data that needs to be studied is the events that are not yet known.  The projection of Dark Matter events is about 1 per year.  We know so far about Dark Matter is that is only interacts with gravity.

DEAP also rents time from the Center of Advanced Computing for their data analysis -- we are talking terabytes of data!!

People we spoke to that day:  
Dr. Patrick Nadeau, DEAP Systems Operator, SNOLAB

Wednesday, December 13, 2017

Day 3 SNOLAB Research Experience -- Wednesday, December 13

Well, I'm feeling much more confident in going down into the mine today.  I arrived at the site at 7:30am and quickly changed into my mining gear, signed in and walked over to the Vale mine building. This is the type of tunnels they call 'the drift'.  It is very dusty and windy!

Today, because there were so many visitors, the cage traveled half speed so it took quite a bit longer to get two kilometers underground.  To be honest, I liked it better on Monday when we went full speed!!  We are planning on staying underground until 4:00pm today.  Right now, that seems like it is going to be a long day.  (in the end --  it didn't feel like a long day at all!!  I think I finally know what I want to be when I grow up -- a SNOLAB Scientist!)

                             Image source:

Once we get to SNOLAB itself, we have to wash off our boots and get ready for the next step.

Of course, we had to shower, wash and dress in special clean clothing again. See that I'm holding a notebook -- I'm trying to learn and write down everything I can.  The picture below is from the ultra-pure water generation system.  The big cylinders to the right are charcoal filters, but the water will go through several steps such as reverse osmosis and deionization before it is clean enough for use with the experiments at SNOLab.

The new SNO+ project is using the same infrastructure from the original SNO experiment.  Please click here to go to the virtual tour page and click on 20, 21 and 22 to view the SNO sphere.  It has 9600 Photo-multiplier tubes (PMTs) on the outside of the acrylic vessel (AV) which is on the inside.  You can see the AV when you click on 20 of the virtual tour.

We had an amazing tour of the scintillator -- which is the purification system for linear alkyl benzene -- or LAB for short. lAB is a dish soap type substance.  This is what they are going to fill the AV with during the SNO+ experiment.  Previously, the scintillator system was tested with ultra-pure water to make sure everything worked and that there were no leaks, and now they are beginning to push LAB through the system to clean out the water and become more and more confident that the system is safe and will work for its intended purpose.  It will take three months or so to flush out all the water.

The big blue tanks are there to hold the LAB prior to purification.  As you can see, the AV of SNO+ will hold a huge volume!!

Here is part of the LAB purifier. Notice all the wiring at the top of the picture.  Every aspect of every valve, flange and container has to be monitored electronically.  The pipes were connected using and expensive, clean and precise type of welding called orbital welding.

Here is the screen of the computer monitoring system.  You can see how complex and multi-step the system is.  The operators of this part of SNO+ are engineers.

One thing to know about LAB is that it is extremely combustible!  And...  remember..  we are 6800 feet under the ground!!  As you can imagine, safety is a huge consideration.

There are special smoke alarms that actually suck in the air and don't have to wait for the smoke to come to them.  It is a very early detection system called VESDA.

There are also many many other fire suppression systems in place all over the underground laboratory.

Next, we went over to the Germanium detectors, which are used to count the radiation of samples of materials used in the experiments.  It is very important that all materials used - including the ultra-pure water - have extremely low radiation levels!  If they didn't -- it would mess up the data used to detect Neutrinos and Dark Matter.  Everything in lab, including the containers and the paint on the walls, needs to have super super low radioactivity.

In the above circular counter the outside very thick ring is made of lead (but covered with copper) and the inner, brighter circle is pure, clean copper.  This is all designed to keep out background radiation such as radon and muons.  This is also why we are so far down underground -- it shields against cosmic radiation and muons.  It takes two to three weeks of counting the sample to get good data about how clean and non-radioactive it is.

The lead bricks in the last picture of a different type of germanium detector uses lead bricks that we down underground in the Windsor salt mines since the 1950s.  This is good to use, because it hasn't been exposed to surface radiation for decades!!

On another note -- Ian, the operator of the counter, also said that we are still measuring the effects of the Fukashima reactor leak!!  (Why isn't this on the news??!!)

Following this,  I was able to job shadow Ana Sofia who is one of the operators of the SNO+ detector.  It isn't up and running yet, but it is filled with ultra-pure water so that the detector can be calibrated.  Ultimately, the AV of the detector will be filled with LAB and a couple of other substances which will make it's sensitivity to neutrinos exponentially greater than the original SNO experiment -- it will also detect the process of neutrino-less double beta decay which will answer two main physics questions:  1.  Are neutrinos their own anti-particle? and 2. What is the actual mass of neutrino?  We know they have mass, but what is it?

To collect the data -- there are 32 data acquisition boards with 512 channels ---  and each channel is connected to one of the 9600 PMTs of the SNO+ detector.

That's a LOT of data!!  The detector needs nano-second precision!!

Each day I understand more and more!  So glad I had I had so many days in a row here!!

People we spoke to that day:  
Paul Larochelle, Operations Engineer at SNOLAB (in the SNO+ Scintillator plant) 
Dr. Ian Lawson, SNOLAB Research Scientist (in the low background counting area) 
Ana Sofia Ignacio, MSc in Physics (the SNO+ detector operator)

Tuesday, December 12, 2017

Day 2 SNOLAB Research Experience -- Tuesday, December 12

It was a blizzard overnight!!  I woke up to minus 25 degrees outside (all the while it was around plus one back at home!!).  It was still too much of an opportunity to miss -- plus I had a researcher, Ken Clarke, catching a ride with me this morning.  He flew in from Queen's University in Kingston, ON last night.

Today was an above-ground day at the surface labs.  The first bit of the morning was more on the importance of Chemists to the physics experiments.

Then we were off to see what Ken Clarke was doing for the day.  Ken works on the PICO experiment and we were able to watch him, Tony, Karston and a grad student work on their prototype.  They worked on the construction for a long time -- but today, they were taking the whole thing apart.   The reason for this is that after this disassembly, they will re-assemble everything while recording the best step by step procedure to build the real thing.  I was told that they will do this a number of times, until they feel they have it perfected enough to proceed with the real experimental structure.  This apparatus is going to be a bubble chamber used to detect dark matter.

Notice how they plan, discuss and argue over the best way to do things. So much actual science is the brainstorming, creative thinking and problem solving.  Also note the fancy outfits and gloves.  Even though this is on the surface, it is a clean assembly room.  And by clean, we mean super super clean!!

This is the cover and the base that will eventually go over the glass structure:

The afternoon was spent at Science North -- one of the biggest Science Centers in Canada.  I had fun on the biology side of things as well.  This great big insect has some of the greatest evolutionary adaptations of camouflage I have ever seen.  (I was a little freaked out by him, but then got a bit more comfortable -- us northern climate people are not too used to BIG BUGS!!)

Close-up of a fly through a super cool microscope.

This is a rhinoceros beetle.  It was HUGE!!

Did you know that 80% of the world's population eats insects as a source of protein?  Here I am joining the rest of the world, eating a chili-lime cricket for the first time.  

It was actually so GOOD that I had a second one!!  Super snack time!!

The coolest thing was the butterfly dwelling.  A couple of them landed on me for a few seconds here and there.  We need one of these in our school -- it was amazingly peaceful and relaxing.

Other things that I saw included a very large snail, a real skeleton of a whale and a porcupine in a tree.

At the Physics display -- I risked my life on a bed of nails:

On the way out of Science North, I was sure to take some pictures of how the building is built right into the rock of the Canadian Shield.

Overall it was another incredible day.  I'm looking forward to going sub-surface tomorrow and Thursday!

People we spoke to that day:  
Dr. Ken Clark, CPARC Research Scientist 
Dr. Tony Noble, Queen's University, CPARC Director   
Dr. Carsten Krauss, University of Alberta 
Dr. Usman Chowdhury, Post Doc at Queens University