More Summer Fun

As I thought, the summer has turned into early fall and I've fallen far behind on keeping up with my blog. Therefore, a few final entries.

A lot has happened since my last entry, but I'll keep this post for all the extracurricular activities. 

Immediately following Zurifaecht, Geneva had their own Lake Parade festival. It was great fun, buying costumes and painting faces. I had bought a set of face paints that week and I still feel that it is the best investment I made this summer. It brings out everyone's inner child when they get their faces painted. Funny enough, while we were sitting in the park and I was painting, three young girls came up to me and asked me (of course in French) whether I could also paint their faces. I did, and they were quite pleased. I'm just glad that I didn't have a lineup after that! Needless to say, there was a lot of music and dancing, but thankfully the city wasn't as crowded as Zurich the weekend before. 

All painted for the Geneva lake parade.

The following weekend was by far the most expensive that I have ever had, but also one of the most memorable ones. I started off by going paragliding in les Saleves just outside Geneva! It was unbelievable and a completely effortless. After a few steps, the parachute inflates and then a few more running leaps and all of a sudden my feet weren't on the ground anymore. Of course, it was done tandem, which probably made it a bit easier as well. Once up in the air, it is a truly amazing and freeing feeling. There is nothing around you, and you can see for kilometers- unbelievable! 

Paragiliding- taken with a GoPro

I would suggest it to anyone who has the opportunity. The instructor also did some neat air acrobatics in which you turn very sharp corners, which is very neat. Also, the thermal updrafts are quite impressive, as well as the control the instructor had. Apparently it is possible to stay up for several hours if planned properly. Following paragliding, I took the train with friends to Montreux for the Montreux Jazz Festival. It is an impressive event, and there were a lot of big names this year including Leonard Cohen, Diana Krall, Of Monsters and Men, and none other than Prince! I saw James Blake live, which was very interesting. He makes some fascinating electronic music. It was very interesting to see how he can mix and modify the sounds to build up a song. Montreux itself is beautiful too so it was a great experience. 

James Blake at the Montreux Jazz Festival

This summer has been filled with everything from zombies at the Geneva CineTransat free open air cinema showing of Shawn of the Dead, pub quizzes on Mondays at the Lady Godiva in Geneva, and terrible summer student karaoke. It has all been fantastic. Swimming at la Jonction, where the Rhone and Arve meet is one of the nicest things to do on a sunny lazy Sunday afternoon. Where the rivers meet, the blue Rhone and brown Arve create a very distinct line, which is quite neat. The current in the Rhone is also quite strong, so it is possible to jump in and float down a kilometer or so without any effort. And repeat!

La Jonction, Geneva

ALICE and LHCb

Time for some more detectors! These last few weeks have been extremely busy with lectures and workshops, plus coding and a lot of summer student events (which I will elaborate on later).

However, my quest to visit all of the four detectors at the LHC has progressed well with a visit to ALICE last week and LHCb yesterday. I only have one left now- CMS which I will visit tomorrow. I spoke a lot about ATLAS, which of course is the detector project I'm working with, but I thought it would be good to give a mention to the others as well.

Beginning with ALICE (A Large Ion Collider Experiment- another testament to the ability of physicist to create strange acronyms), it is located at Point 2 just outside St Genis-Pouilly in France.
As its name suggests, the experiment is focused on using heavy ions (nuclei with some electrons removed to make it charged) such as lead to explore questions such as "Can we create free quarks?" Theory says that at the energy levels explored thus far, quarks (the constituents of protons, neutrons, and all hadrons) can't exist by themselves, but in the first few instances of the universe, it should have been possible. This is what ALICE hopes to examine.

As I mentioned, ALICE uses heavy ions for this research, but you might wonder- I thought the LHC collided protons? In fact, they also collide these ions! Even more interestingly, they have also done proton-lead collisions, which is neat because a lead ion has 82 protons and ~125 neutrons, meaning that it is roughly 200 times more massive than a proton. This is like colliding a mosquito with a nickle (in terms of relative masses)!

For some more detailed information on what they do: http://aliceinfo.cern.ch/Public/Welcome.html

ALICE

The detector itself is considerably smaller than ATLAS at 16 meters in diameter and 26 meters in length, but it weighs 10 000 tonnes! The setup itself is not so different from ATLAS,  in that it also involves an inner tracking detector, calorimeters and a muon detector. However, lead-lead collisions are very messy compared to proton-proton collisions which means that ALICE has to be able to collect a lot of data very quickly. Each event is over 10^7 bytes and there are roughly 1000 events per second. Considering that a CD holds 700 million bytes, this data collection is the equivalent of ~14 CD's per second! In total, they store over a petabyte per year (10^15 bytes).

Well, enough about ALICE, what about LHCb (Large Hadron Collider beauty experiment)? On the map above, it is locate at Point 8, just outside Meyrin. It is actually the deepest of the four detectors, being 100 meters underground. As you may have guessed, LHCb studyies what are known as "beauty" quarks, more commonly known as "bottom" quarks which only live for a million millionth of a second. These quarks can help us learn about the reason why our universe is made up of matter rather than antimatter- where has all the antimatter gone? It may also offer some explanation of dark matter, which makes up roughly 26% of our universe. (The number varies- I don't think I've ever seen two presentations with the same percentages.)

LHCb is also quite unique in it's setup. Rather than being built around the beam line and having the collision in the center, the collision actually occurs at one end of the detector. This is because the beauty quarks tend to travel very close to the beam line, meaning that it's really only necessary to look in one direction. So the detector is very much like a stack of pancakes. It also has some special detectors, such as the Cherenkov detectors, which help measure the particle's speed. When light travels through a material, it slows down, which means that it is possible for a particle to travel faster than the speed of light (but only in that material- NOT in a vacuum!!) This creates something like an optical sonic boom, which is then measured. It also has the usual tracking detectors, calorimeters and muon detectors too.

All of these detectors are unique and beautiful. I'm really lucky to be able to see them- it's a true testament to amazing engineering and innovation!

LHCb

ZueriFaescht 2013

Since the last post was quite heavy on the physics, I'll have a post just about all the fun things that have happened the last few days.

This last week has been very busy with the beginning of the summer school lectures (which I will discuss later) on top of everything else. In my free time, I've had the opportunity to explore Geneva, watch some soccer games and join in an amazing Zumba class, go for a run through the woods and participate in an early morning workout session. There's no time to rest!

However, this last weekend, it was Zurich's turn. Every three years, Zurich holds a massive festival called ZueriFaescht. With an expected 2 million people over the course of 3 days, this is an event that simply couldn't be missed. However, with so many people, I was shocked that we could keep together as a group. Of course, without our cellphones, it wouldn't have been possible- thank goodness for modern technology.

The lake and some of the crowd

The festival was massive, and included everything one could possibly imagine. There were food stands, bars, DJ's, live music, tightrope walking, marching band parades, a huge ferris wheel and fireworks! All along the river side and along the lake, there were people from all across the world, the weather was beautiful and the atmosphere of the city was amazing!

Tightrope walking- 200 meters across the river

Lights at the beginning of the fireworks being dropped with parachutes from a helicopter. I liked the out-of-focus effect.

Apart from the festival itself though, I also had a chance to see some of the city, primarily ETH Zurich. It is a fantastic school for physics, and one that I would like to study at. It is a beautiful campus with a great view over the city. Unfortunately, since it was a Sunday, some of the buildings were locked, but I did go into the zoological exhibition, which was very well done. On Sunday morning, I also happened to meet someone on the train from Seattle who was studying at ETH. It's a small world! I was glad to have the opportunity to ask some questions.

ETH Zurich on the hill

The view from ETH

Zurich also has some fantastic cathedrals, namely the Grossmunster, Fraumunster and St.Peter's. This gives it quite a different feeling from Geneva, which is much more modern architecturally. In general, Zurich is also a very clean city, and this weekend was a true testament to the efficiency of the workforce there. The amount of glass and garbage on the ground by 2:00 in the morning was horrendous, and yet, several hours later, there was little evidence. It was very impressive. I'm just not sure if the smells were typical of the city or not...

Grossmunster

The Ferris wheel at Fraumunster

ATLAS

Other than perhaps last summer, this is certainly the best time to be at CERN. Thanks to the shutdown for upgrades that will last until 2015, we get to go down and visit the detectors!

ATLAS (A Toroidal Lhc ApparatuS)

It's true that no matter how many times you read about the ATLAS detector, and are told how big it is, once you see it, it's still mindboggling. Some numbers:

• 25 meters in diameter  and 46 meters long = half the size of Notre Dame in Paris
• weighs 7000 tonnes = the Eiffel tower weighs 7300 tonnes!
• 3000 km of cables

Some interesting facts:

• The data that is outputted in one year from the detector is 3200 terabytes, or 7 km of CD's stacked on top of each other
• The cavern was built from the top down
• They had to first put down 5 meters of concrete to hold the weight of the detector
• The detector was built using an access shaft, similar to a ship in a bottle
• Every year, the detector rises ~0.5 mm because the cavern acts a bit like a bubble in honey! They can adjust for this though.

The access shaft

So how does the detector actually work? It's a lot like a gigantic camera, and each layer looks at a particular part of a particle collision. It's starts off with sending two proton beams (or whatever you may have on hand) through the beam line, and colliding them at the detector - sounds simple, but it's more like firing two needles at each other, and expecting them to hit head on. However, the protons come in what are called "bunches", and each "bunch crossing" will have something along the lines of 20 collisions. It's not a lot, but because they can send the protons so fast, they can actually get 40 million crossings per second! This is approximately 1 million collisions per second. Of course, this is too much information for computer systems to handle, so there are triggers that filter the incoming data to only 200 INTERESTING events per second. This means the systems need to be told what is interesting- something like the Higgs boson.

That's how the data arrives, but how can we determine which particles came out of the collisions? This is where all the individual parts come in. I will quickly discuss their purpose, but I won't go into the details, because otherwise this would turn into an essay. If anyone is interested though: 

http://www.atlas.ch/pdf/ATLAS_fact_sheets.pdf

The first section is the Inner Detector (ID). This section lies right next to the beam line and is the first thing to be hit after a collision. This detector records the particles as they pass through the pixels and through this, it is possible to reconstruct a "track". The ID is also surrounded by magnets. This magnetic field will cause a charged particle to curve, meaning that we can then figure out how fast it was going and what its charge was (positive or negative). 

The second part is the Calorimeter. There is an electromagnetic and hadronic calorimeter, which focus on mostly electrons/photons and protons/neutrons respectively, even though there is some overlap. The Calorimeters actually "destroy" the particles by having them collide with material, and then the amount of energy that is left behind can tell us the energy and momentum of the incoming particles.

The endcap muon detector

More of the muon detector. The orange-striped pipes are huge toroid magnets.

The last piece is the Muon Detector (this is what you can see in the picture). Muons are a bit like heavy electrons, and they can pass through most of the detector with almost no problems. That's why the muon detector is the furthest outside. As particles pass through, they ionize the material in the muon detector (strip the electrons), and this can tell us when a muon arrived, and if we have enough pieces being hit by the muon, we can also determine the path it took. This section is also surrounded by magnets, which you can see in the picture too (they have the orange bands).

Mont Blanc, Lake Geneva and the Higgs boson!

I think this weekend, I would have made my French teachers proud! I was lucky enough to have some family visit me, and had a wonderful (though perhaps slightly stressful at times)  few days with them. Having a car is very useful, since it makes travelling a lot easier, but it helps to have a good GPS. I can't count the number of times "she" tried to take us off the highway, though the signs all said Geneva -20 km, or the closed streets where we just had to guess the general direction we needed to go in. But in the end, we made it.

I think I'm going to go in reverse chronological order, because I want to leave the physics for last. Sunday was a breathtaking experience (almost literally). We visited Chamonix, which lies in France, at the foot of Mont Blanc.

The church clock tower in Chamonix

 From there, we took the gondola up 3842 meters to visit the mountain. It was absolutely unbelievable! You travel up the mountain, and much of the trip was through thick clouds. However, as you reach the top, you pass through the top of the cloud cover, and emerge in a stunning alpine vista.

Reaching the summit.

 The pictures just don't do it justice. And to see all the people that are climbing the mountain- it's fantastic.

Mountaineers.

Even though I knew it would be, I was still surprised at how much thinner the air would be up there. Going up just a few stairs made me feel completely out of breath.

Mont Blanc (slightly hidden)

At 3842 meters, with the TRU moose!

Looking back down at the main platform

We also had a beautiful, sunny Saturday driving around Lake Geneva, and visiting the beautiful cities along the way. After lunch at the Mont Blanc hotel in Morges...

Family at Morges

...we continued on to Montreux. Apart from all the expensive casinos, and amazing lake views, Montreux is also home to a Freddie Mercury memorial, unveiled in 1996, due to Mountain Studios where Queen recorded some of their songs, but also because of Mercury's love of the city. I can see why, too!

Vineyards on the way to Montreux.

Freddie Mercury- "Lover of Life, Singer of Songs"

The mountain views

The fantastic Lake Geneva.

From Montreux, we continued on along the lake until we reached the small medieval town of Yvoire. It is absolutely beautiful, the small arts shops, the restaurants, church and of course, the view.

The houses in Yvoire.

I also noticed another very interesting statue when leaving the town. Mostly, I noticed because what looked like graffiti on the base was actually a series of physics equations and notes. This statue, is supposed to represent the recent discovery of the Higgs boson! That actually brings me to a more work related topic.

The Higgs boson- personified.

Most people have by now probably heard of the Higgs boson, but what I always find so amazing, is the way they found it. In the 1960's, Dr. Peter Higgs proposed what is called the Higgs field and the overarching Higgs mechanism. I included some links in the previous post, and if anyone is interested in some details:
http://arxiv.org/pdf/1207.2146v2.pdf
Beware - there is math involved!

Now, according to the Standard Model (the model that we use to describe the electromagnetic, strong and weak forces as well as particle interactions through these forces) each of the forces is mediated by an associated particle (which are called bosons). For example, let's say we have two electrons come together. Everyone learns in high school that like charges repel, but this repulsion is not just "magic". The Standard Model says that the repulsion is actually caused by one electron emitting one of these mediating particles, a photon in this case, and the other absorbing it. For the strong and weak forces, they are mediated by the W and Z bosons. However, the photon is massless, the W and Z are very heavy (Z is around 90 GeV. **Just a note- GeV is one billion eV, the energy of one electron accelerated across a 1V potential (like a 1V battery). However, in particle physics, because of Einstein's E=mc^2, it is used as a measure of mass). A huge question was, why this difference? This is where the Higgs boson became important; it was introduced to explain why certain particles are very heavy while other are light. In the simplest terms, it has to do with how much the particles "like" the field- I always like the dinner party analogy
http://www.exploratorium.edu/origins/cern/ideas/cartoon.html

The big problem was, though this theory could predict how the field would cause particles to have mass as well as how the Higgs boson could possibly decay (break up into other particles), it said nothing about how heavy it was. So, for approximately the last 30 years, first with LEP (Large Electron -Positron collider) and SLAC (Stanford Linear Accelerator Center) and now with the LHC (Large Hadron Collider), experimentalists have been searching for evidence. Based on the models we have, physicists had to comb through a very wide range of masses, and using what we know about how the boson should decay, they could determine (statistically) whether or not the data showed any excess. I may go into what this "excess" is a bit later. For now, it is enough to say that a lot of processes can mimic the Higgs boson (known as background) and the real boson would look like some extra Higgs signal- a bump- exceeding what we expect from the background.

After after years of ruling out various mass regions, physicists have finally found that "bump". Now, it's just a matter of seeing whether or not the data agrees completely with the theory in terms of charge, something known as spin, and other properties we would expect the Higgs boson to have.

Getting started at CERN

Well, I suppose that since I've been here for a week, I should get started with blog posts as promised. I will be using this to document random interesting facts about my time at CERN as well as some pictures of my time here.

Some background I suppose...

I am a fourth year (going into fifth year) student at Thompson Rivers University studying Physics and Honors Mathematics. I began this summer working with Dr. Dugan O'Neil at SFU in May as part of the SFU ATLAS group. ATLAS is one of the major detector experiments at CERN and is the project that Canada is primarily involved in. To learn more about ATLAS or ATLAS Canada, the following are great sites:
http://atlas.ch/,
http://www.atlas-canada.ca/

In particular, I have been working in the Higgs --> tau tau group. Now, the Higgs boson, which many of you have probably heard about since the announcement on July 4th 2012 of its discovery (and if not CERN has some fantastic resources: http://home.web.cern.ch/about/physics/search-higgs-boson), only lasts for a very short time before decaying into other particles. Using detectors like ATLAS, we can "see" these decays particles and trace them back to the Higgs itself. One of the main ways the Higgs can decay is to two tau particles (which then decay even further), and this is the area I'm working in.

Now this work is done all through programming. For this project, I've been learning Python, which if anyone is interested in learning, is actually a really nice and quite straightforward language to use. I can certainly recommend the following book for anyone starting out:
http://briggs.net.nz/snake-wrangling-for-kids.html

And now for CERN....

Since having arrived on Saturday, I've been familiarizing myself with the CERN "campus". I can't begin to say how convenient it is being able to walk only 100 meters and reach my office, the cafeteria and most meeting rooms, not to mention that I have a view of the Alps!

That's building 40 to the right, home to the ATLAS and CMS secretariats.

Inside building 40

Speaking of the cafeteria, the food here is amazing (of course), but rather expensive, as with most of the Geneva area.

At the moment, it is pouring buckets outside my office window, but for the last few days, it's been unbelievably humid. Luckily there is a pool not too far away, to provide some relief from the heat. Nonetheless, in the evenings, when it cools down a bit, it is nice to sit outside with other summer students and discuss life, the universe and everything. It's not often that you can have drinks with someone from the UK, USA, Greece, Norway and Finland all at once!

In my opinion, other than of course the unbelievable science and fundamental discoveries being made here, the people you meet and interact with here are the most amazing part about CERN. Though nearly everyone here speaks French or English in a group of 10 people, there are likely to be 6 countries represented. Everything from Madagascar and China to Costa Rica and Iceland.

Working in the office- a bit empty at the moment...