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Archive for August, 2009

“Yonupa” Summer school.

Monday, August 31st, 2009

Annual summer school for graduate students majoring particle and nuclear physics is held in Nagano prefecture, in the middle of Japan. This time, after 10 years, I visited this school again, as a lecturer. It is nice to visit any places where I spent many days in my younger days. I have attended at the school every year when I was a graduate student. It was so joyful experience.

Before I got to the school venue, I was wondering if nature of young students may be very different from the one in my old days. But as soon as I started the lecture, this concern just went away. The summer school was really the same as before, nothing has changed, except for the names of the participants. It is very very good. This summer has nothing different from summers I experienced 10 years ago. Young graduates get to know each other and enjoy chatting, drinking, hiking and physics.

I in fact enjoyed giving lectures and a party after the lecture. I had opportunity to talk with fresh graduates. I hope this activity of the annual summer school will continue in the future. Since the organization of the summer school is completely by the graduate students themselves, I know it is kind of difficult to continue, but anyway this activity lasts at least for more than fourty years, and this fact encourages me to expect that this continues forever….

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Sick days

Sunday, August 30th, 2009

Ah, the beginning of fall semester. All the undergrads come back, the weather changes, and everyone gets caught up in the hustle and bustle of a new term. In other words, the perfect storm for viruses.

On Thursday a rather hectic week caught up with me and I found myself feeling rather ill. I ran up a bit of a fever before eventually being able to head back to my apartment to hibernate for the better part of the weekend. Thankfully I’m much better now and can catch up on some paper reading for next week.

What I’ve come to realize is a double edged sword in grad student life. While we have a tremendous amount of freedom in how we spend our time, it’s really tough when one has to take some sick days off. It’s not that people aren’t sympathetic or willing to give you some time to recuperate (especially these days with H1N1 in the back of everyone’s minds), but rather that research doesn’t stop when a grad student gets sick. The more time one takes off the more there is to catch up on. I’m responsible to keep up with collaborators and to provide meaningful input, so I have to make sure that I keep up with my project even when I’m out-of-commission.

Fortunately my illness passed rather quickly and I have the weekend to properly recover and catch up with what I’ve missed.

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Gone with the Wind

Sunday, August 30th, 2009

Last week I went camping on a northern German island – Spiekeroog. It is a beautiful little East Frisian island just off the German coast where no cars are allowed. The campground was very natural with little dunes and sandy – just beautiful even so it was difficult to find a flat spot for the tent. In the first night I was sleeping not too well as I was always sliding towards the far end of my sleeping mat. But this is normal when camping and part of the game. During the days we did long hikes along the beaches, went swimming or when it was windier, played with the stunt kite. This mini vacation was only a few days, but really nice and great fun.

In the end the wind increase quite a bit and my tent started to have problems. As we were planning to leave in the evening, I decided to take it down and pack it up. But somehow the tent decided to crash before I was done with packing….

My tent in the wind

My tent in the wind

... and after it collapsed while I was removing my stuff.

... and after it collapsed while I was removing my stuff.

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A tour of SNOLAB

Saturday, August 29th, 2009

Our EXO Collaboration meeting began with an excellent tour of the SNOLAB facility. Our guide – Samantha – did a wonderful job of leading our exceedingly large group through the mine and answering all of our questions. While it is not my first time underground – I’ve possibly logged 220 hours underground already at WIPP – this was the deepest I’ve ever been. While WIPP is 2150 ft underground, it is still above sea level. SNOLAB is 2km underground (currently the deepest science facility in the world), which is about 5600 ft below sea level. The depth certainly is noticeable: while both involve pressure changes as you descend in the alarmingly-loud lift, at SNOLAB the pressure change is much greater and the ambient rock temperature is 42C (108F) once you reach the bottom. I was quite concerned that this would make the faciilty a giant sauna – and we were warned to wear little clothing under the mine gear – but it wasn’t too bad. At least, I’ve been as sweaty at WIPP after a long walk and there the temperature is close to room temperature.

I was surprised by certain differences in the mines themselves. The mine SNOLAB is located in (Vale/Inco) is a nickel mine, while WIPP is a salt mine. This makes the mining process very different, especially since SNOLAB is located in a private mine run for profit while WIPP is a government facility for storing nuclear waste. Hence, Vale/Inco is concerned with getting as much nickel ore out as quickly as possible, while WIPP just wants a place to put the nuclear waste (as safely as possible). One big difference is the size – while I’m not sure how big the Vale/Inco mine is in itself, the area we were in today was certainly a small fraction and it likely rivaled the entire size of WIPP. Another is the size and condition of the drifts – at WIPP most of the drifts are very large, flat, and wide, while we walked through some much smaller areas today. There are tracks running through the drifts at the Vale/Inco mine for the carts they use, while at WIPP things tend to be more vehicular. This meant we did more walking today than we usually do at WIPP!

Perhaps the biggest difference (to me) was that SNOLAB has toilets. Proper toilets. WIPP mostly has porta-jons, while there is at least one mini-sewage treatment toilet underground at WIPP (it is a glorified porta-jon). At WIPP, the port-jons are scattered throughout the underground and are pumped out a few times a week. This fills the downwind drifts with an absolutely horrible stench that is overpowering even inside our clean rooms! In the underground at Vale/Inco they have a small sewage treatment facility that can support about 100 people (the SNOLAB facility currently is supporting about 40) and only a small amount of waste needs to be shipped above ground. There seemed to be no smell, even when looking directly into the open treatment tank.

Of course, the most meaningful difference is that everywhere at WIPP that isn’t within our cleanrooms is a salty environment. SNOLAB is a large, class-2000 (or better) clean room facility. Once they finish the expansion, they will have about 5000 m2 of clean room facility. Our clean room facility for EXO-200 is something close to 60 m2 (though it is a “more clean” area than SNOLAB). At WIPP we go in and out of the clean rooms, changing between clean room suits and mine gear. We have to leave the clean room if we want to eat something, use the porta-jon, or scratch our head. At SNOLAB, you leave your mine clothes at the door, take a shower, and put on clean room gear. Then you enter an area where there are physics experiments, computers, eating facilities, and toilets. It was quite civilized!

I’m very impressed with the lab. Not only is there an unimaginably large area – kilometers underground – that has complete infrastructure for scientific work, but it has been implemented at the class-2000 clean room level. Every cable and piece of support structure has been cleaned by hand. There are indescribably huge caverns for future experiments – it feels like walking into the bottom of a professional football arena. And then, crowning it all, is the SNO detector.

The SNO detector has a special place in physics history, because it is (more or less) where measurements were made that proved that neutrinos oscillated. And that meant they had mass. While SNO wasn’t the first experiment to measure solar neutrinos, it did it in a way that was more definitive than previous experiments. This has special meaning for me, as I was in high school at the time and remember when the science magazines covered their first results in 2001. This was the experiment that showed me we didn’t yet know everything about particle physics.

The SNO detector is still there, being refitted to look for a different types of reactions, including neutrinoless double beta decay. I won’t hold it against it that it will be competing with EXO, because it is the most beautiful thing I have ever seen. It is a huge sphere, covered with photomultiplier tubes (PMT’s) looking inwards, with a few looking outside the detector. For most of its operation it was filled with heavy water, where PMT’s would detect rings of light left by relativistic particles. Because it was empty, we were able to look both inside and outside the detector, from above. At 6m in radius, it is a large structure. But more importantly, it is impressive in its perfection. Over a million pieces were brought into the mine to be assembled, including acrylic pieces that form the sphere itself. They were carefully bonded together and inspected, and then carefully sealed. The PMT’s are themselves impressive on their own, but this has a large quantity are precisely installed.

It felt like viewing an ancient cathedral. No picture will be able to capture how small it makes you feel. Numbers alone do not do it justice. Realizing how many people poured their effort into it and how its influence has been felt around the world and how close you are to the location where the most important neutrinos were – it makes history seem so small – how else could someone so insignificant as me get so close to it. It was quite awe inspiring.

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Well, I have been about the worst blogger in the world recently. Not by writing bad posts, or boring posts, or outrageous or insulting posts, but rather by writing no posts at all. It’s been another hectic month at Fermilab, at conferences and workshops, even a few days of vacation squeezed in there.

One thing definitely worth sharing here on QD is the grand finale of the Science Chicago LabFest! events which happened recently downtown at Chicago’s Millennium Park. I mentioned the LabFest events in an earlier post, but they are outdoor science fairs which have been organized by Science Chicago and have occurred in parks and at schools all over the Chicago area over the past year. A group from Fermilab has been at each event through the summer with our van full of displays and interactive demonstrations. The Millennium Park event was the final LabFest of the summer and the fourth one that I have attended.

The Fermilab tent at the Millennium Park LabFest with the Pritzker Pavillion in the backgroud.

The Fermilab tent at the Millennium Park LabFest with the Pritzker Pavillion in the background.

Kids roaming the grounds at Millennium Park LabFest.

Kids roaming the grounds at Millennium Park LabFest with the Chicago Art Institute in the background.

Beyond the remarkable venue, however, this LabFest was special because I got to do, with another physicist from Fermilab, a 20 minute stage presentation using liquid nitrogen. Mike Cooke and I met with the master of the cryo show, Mr Freeze (a.k.a. Jerry Zimmerman from Fermilab), before the show and he was kind enough to let us borrow his stage equipment.

Jerry’s normal show runs about an hour, so it was a challenge to pick and choose the bits we would fit into 20 minutes but maintain some continuity in the material. We began by giving some idea of the basic properties of liquid nitrogen. What is it? Basically liquid air since nitrogen makes up almost 80% of the atmosphere. How cold is it? -321 degrees Fahrenheit. Yikes, not even a Chicago winter compares!  What does it look like? Pour some into a plastic ziplock bag and note that it looks like water, but is boiling at room temperature, so it can’t be water.

Next we explored the expansion that occurs as the liquid nitrogen (LN) rapidly boils into a gas.  Sealing the ziplock bag quickly leads to it ballooning until it ruptures.  Next a typical kitchen garbage bag (~13 gallons) is loaded up with 1 cup of LN and sealed with the same destructive results.  Finally, a lawn garbage bag (~45 gallons = 720 cups) is used and, upon fully inflating, is shown to barely contain 1 cup of liquid nitrogen converted into gas.  The expansion ratio is 700:1.  At this point, as a foreshadowing of things to come, Mike poured a small amount into a 20 oz. plastic bottle and sealed the cap, holding it up to the excited kids in the front rows.  They seemed to really get the point as a few began screaming that it would explode!  Fortunately, this was a fake as Mike showed them the hole he had punctured in the bottle cap before the show – but the setup was successful 🙂

Filling the special containers with liquid nitrogen for the show from supplies at Fermilab.

Filling the special containers with liquid nitrogen for the show from supplies at Fermilab.

Mike and I rehearsing our show at the Lederman Science Center at Fermilab.

Mike and I rehearsing our show at the Lederman Science Center at Fermilab.

We then showed some examples of how liquid nitrogen can be used to change the properties of materials that it comes in contact with. At Fermilab, we use liquid nitrogen (and even colder liquid helium) to change some metals to become superconducting. It is these superconducting materials that are needed to produce the strong magnetic fields used to steer super high-energy protons in the accelerator.

First we used inflated balloons to show how the air inside them could be liquefied by making it cold with LN. This causes the reverse of the expansion we explored earlier, namely a ~700:1 contraction of the volume, so the balloons collapse down. Removing them from the liquid nitrogen, they slowly warm back up, crackling and twisting around like some kind of monster as they grow back to their original size. In fact, to really show the dramatic effect of contraction as the gas liquefies, we go on to pull out about a dozen large balloons we had placed before the show into a tiny dewar that they never could have fit into while fully expanded.

What about solid objects that are cooled down so much with liquid nitrogen? They don’t contract enough for the audience to see (but they certainly do contract some, as all objects do when they get cold), but their properties change in other dramatic ways. To demonstrate this we used a racquetball, a rubber glove, a small (4 inch) inflatable plastic basketball, and bananas. The racquetball goes from super bouncy to a loud crack and thud on the stage floor without much of a bounce. The soft (at room temperature) rubber glove becomes brittle to the point where the fingers can be shattered off. We set this up, of course, with Mike appearing to stick his hand into the LN dewar and me shouting that “It’s the wrong safety glove!”. He quickly pulled his hand out and shattered the fingers off revealing his safely recessed hand, much to the delight of our audience. The plastic basketball not only becomes rock hard like the racquetball, but also the air inside contracts as it liquefies, so there is no air pressure pushing out from the inside. A quick tap with the tongs and the previously rubbery, squeezable ball shatters into 1000 pieces like a light bulb.

The bananas were used to make a hammer. Mike begins to peel a banana claiming that he can use it to drive a nail into a piece of wood. I say that I don’t believe him and begin to peel my own banana which I use, at room temperature, to strike a nail. Of course, the banana breaks apart and bits of mushy banana fly around. Mike dunks his into LN to freeze the banana in a matter of moments making it super hard and successfully drives in a nail.

The view from the stage where we would be performing our show.

The view from the stage where we would be performing our show.

About time for the grand finale, don’t you think? For this, of course, we used the Cryo Cannon! A steel tub about 3 feet long and 4 inches in diameter was standing up on the concrete just off the stage to the right. We reminded the kids about the pressure built up from the expanding nitrogen when it boils as we placed a small amount into a 20 oz. soda bottle. We explained to them that we would use the release of this pressure to launch one of these small plastic basketballs into the air. “How high do you think we can launch this thing? 20 feet? 50 feet?” It was like an auction where money (or height) was no object to the purchasers – I think one kid offered 1,000 feet. Mike sealed the bottle, this time using a non-punctured cap, dropped it into the vertical metal tube, I dropped the “cannon ball” (plastic basketball) in on top, and about 15 seconds later – BOOM!, the ball was launched somewhere around 150 feet probably (about a 15 story building). There was a slight breeze from the west, so the thing floated east towards Lake Michigan as a dozen kids from the front rows tore off in chase to claim their souvenir.

Several people from the Fermilab Office of Communications were there and soon there should be an article about the event in Symmetry Magazine. Also, Susan Dahl, from the Education Office at Fermilab video recorded the cryo show, so I’ll pass those links along when they are available.

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Complexity and reliability

Thursday, August 27th, 2009

I rather enjoyed this article that appeared in this week’s CERN Bulletin about the LHC schedule. It reminds us of just how much work is going on behind the scenes — or at least, behind the scenes if you are an experimenter patiently waiting for beam, as opposed to all the accelerator people actually doing the work. The LHC, like any large accelerator, is actually built from many individual systems that interact with each other, and doing something in one system can have effects in the others. Coordinating all of the work that is being done right now is a huge task that requires careful control. (I actually have similar thoughts when I go to visit our new physics building, which is currently under construction. So many details to keep track of in building a building, and it’s not nearly as big as the LHC. (Physics majors of the world: ask me about our graduate program in physics and our lovely new building!))

There are two other things that I took away from this article. The first is that while the LHC startup date has slipped a little bit from the announced plan in February (from late September to mid-November), CERN has actually completed much more work since then than they had originally anticipated doing. This should give us a more reliable LHC than we would have had otherwise, which to me seems worth the very slight additional wait. The second is that CERN is so focused on providing a reliable machine, so that there will be reduced risk of a delay as long as the one we are currently living through — and an increased chance of observing new physics soon.

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Leysin, Switzerland

Thursday, August 27th, 2009

This week I’ve had the pleasure of attending the egamma conference in the quaint mountain town of Leysin nestled in the Swiss Alps. As I look at the beautiful scenery from my hotel room, I can’t help but be reminded of songs from the Sound of Music. In the distance I can imagine a traveling band of singing youngsters wearing drapes while crossing the mountains. (The Sound of Music is my mom’s favorite movie and on her birthday she makes us watch it). I also think back about my home in Colorado. I was fortunate in that I learned to ski young, so I don’t have the completely rational fear of death by tree. I guess it’s the wrong season for that now, but it’s clear that the town is more geared towards winter than summer (which I’m sure is why we had the conference here at this time of year).

A view of the conference hotel

A view of the conference hotel

In reality, the conference could have been in any place since the meetings run consistently from 9 am to 7 pm (breaks for lunch and coffee, of course). As I sit in the room trying to pay attention to the person who holds the microphone just far enough away so that no one can hear him, I think to myself people weren’t meant to sit in meetings for 8 hours a day for days at a time. As I look around the room, my feelings are validated by a sea of people with laptops that have terminals and emails open. Maybe later this morning I’ll convince myself that it’s OK to skip a session and go up the telecabine to the top of the mountain.

Until then, back to fake rates and signal efficiencies

-Regina

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Occupational Hazards

Wednesday, August 26th, 2009

As a physicist, it is easy to imagine that the majority of our occupational hazards can be prevented with good safety practice. We all go through extensive training regarding radiation, cryogenics, lasers, heavy equipment, electricity, power tools, ladders, and even computer use. I’ve found myself a victim of one of those tragedies that often afflicts my profession: chronic wrist pain.

I do not have a simple RSI like Carpal Tunnel. I did something bad to it when machining a few years ago, which was aggravated by how I was carrying my bike up and down stairs. Soon I found myself having difficulty doing dishes and getting dressed. So I saw a doctor, took some ibuprofen, and kept my wrist in a brace during any significant lifting. Of course, this is my dominant hand I injured.

Eventually the pain stopped, but reoccurred after a few months. It was re-triggered by torquing my wrist too far back. The pattern repeated for a while with the latest occurrence beginning about 2 weeks ago. Now it has even begun to hurt when typing, so I revisited the clinic (where I was given a totally different diagnosis) and began physical therapy. Of course, this injury now coincides with the preparation of a talk and the writing of a paper, so typing is not something I can currently avoid.

Tomorrow I leave for Canada for the second EXO Collaboration meeting of the year. I’m quite excited to visit SNOLab and to give my wrist a chance to heal some. When I’m a work I’m either lifting things or typing, so a week of talks will be a welcome break. While I could be tempted to update documentation during the talks, I have a great excuse to close the laptop lid and not multi-task: another occupational hazard!

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Around the time of my birthday, I broke my little toe whilst dancing. After a few days of struggling, I begrudgingly went to the nearest Swiss hospital for a scan. A few weeks on, I found something in my letterbox that I assumed would be a bill, but instead it was a copy of my foot x-ray! This made my day, because, as you will see below, I have an uncommonly interesting foot!

X-rays provide proof that Zoe is wierd on the inside

X-rays provide proof that Zoe is wierd on the inside

If you look carefully on the left you can see the break on the little-toe proximal phalanx that caused this picture to be possible. However, the most striking part is on the right – two big screws! A few years ago I had an operation to fix a “bunion”. This was a deformation of bone, where the big toe bent inwards, its metatarsal separated from the others leaving a big gap, and a large bone growth formed at the base making shoes painful, uncomfortable and prone to getting holes worn into them! The surgeon removed the bone and broke the toe, cut tendons and screwed into my bones – it took a long recovery, and I was saddened at the time to not be allowed a copy of the x-ray “before-and-after” pictures! So to get this in my postbox was like a late birthday present (even if it came with a rather irritating side-effect!)

I still wish I had a picture of my other interesting skeletal oddity – I have a spare rib in my neck. Yes, you read that correctly.  1 in 500 people have one. Under X-rays, I look like a slightly lopsided Frankenstein.

This has got me thinking – if you wanted to start talking about electromagnetic radiation and its applications you could spend a lifetime. I would like to dedicate the next few blogs to some interesting and taken-for-granted uses (and unusual behaviours) of various parts of the EM spectrum, linking the apparently mundane and ordinary to the extreme, and to the work particle physicists are doing with it.

We have been having some very stormy nights here in St Genis, France. The lightning has been falling very close to where I and some other CERN PhD students live, and it is interesting to see how fascinated we all are as physicists by the experience – we have an almost childlike excitement about it (and in my case, a very childlike fear!) Natural lightning has been measured to produce x-rays, but it isn’t very well understood why (it doesn’t reach temperatures anywhere near hot enough to explain it). However, the x-rays are apparently quite useful in helping scientists try to predict the path of otherwise fairly unpredictable lightning strikes.

Interesting stuff! I will come back to the topic of X-rays when I have more time.

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Now I get it!

Tuesday, August 25th, 2009

For a considerable fraction of the students starting grad school in the US, September is a synonym for the dreaded qualifying exams. These tests are meant to check our mastery of undergraduate-level physics, so we can move on and take the graduate level courses with confidence in what we’re doing. Of course, for many students (and for me as well, depending on the day and my level of exhaustion) they rather mean plain torture.

Getting ready for an exam like this involves solving literally hundreds of problems that will cover a wide spectrum of topics in physics: classical and quantum mechanics, relativity, thermodynamics and statistical mechanics, electricity and magnetism, etc.
While doing all these practice tests I wondered about how, sometimes you would have no idea about how to tackle a problem and then, suddenly, something magical happens, you understand.

Montgomery Burns 1000 monkeys writing on 1000 typing machines

Montgomery Burns' 1000 monkeys writing on 1000 typing machines.

This rather trivial, everyday event has always intrigued me. Nothing has changed, you’re staring at the paper like you did two seconds ago, but in your head there is a big neon sign saying: “hey, I know what this is about!”

I wonder about what the brain is actually trying to do in those cases, maybe it just dumping all the memories related to problems like the one you’re reading, trying to make something fit. This is probably not so elegant, it would probably make several neurobiologists turn red, and it reminds me a bit of that idea that an infinite number of monkeys hitting keys in typewriters should be able to produce the complete works of Shakespeare, but indeed it’s a mysterious phenomenon.

On a side note, this also reminds me of a great satire about the work of people in academia: “Gulliver’s Travels” by Jonathan Swift. On one of his travels, Captain Gulliver visits an Academy where he is shown a machine that can produce all the knowledge of the world. It’s basically a grid of rotating cubes with words of them; some assistants would rotate the cubes and then take note of the resulting combination of words, then creating “new knowledge”. Here’s a sketch of the machine, from the first edition of Gulliver’s Travels.

Ironically, this great book loaded with tons of dark humor ended up being considered as a book for kids.

No matter what the process involved is, understanding something is one of the great pleasures of physics and, I think, of science in general. Training ourselves to solve these problems should help us in developing our instinct on how to solve other, not so trivial questions that we may encounter during our careers. If we are very lucky, we’ll be able to provide answers or hints to those as well. In a way, it’s very similar to a detective’s job, as Zoe mentioned some time ago.

This pleasure, the pleasure of finding things out as Feynman put it, it’s the driving force for many of us in this field. If the thing you have figured out is very important, you can certainly understand Archimedes’ reaction, running naked down the streets of Syracuse screaming “Eureka!” (I found it!) when he understood what we now call the Archimedes principle. And probably also, more recently, you could understand Kary Mullins pulling his Honda Civic to the side of a Californian road to be able to think about the implications of the idea that made him receive the 1993 Nobel prize in chemistry, and that made him exclaim something that it’s, in a way, close to Archimedes’ Eureka, but I will leave to you to find out.

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