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Archive for September, 2009

Deadline day

Wednesday, September 30th, 2009

Did you see any physics professors who looked both tired and relieved today? It could be that they had just submitted their grant proposal to the National Science Foundation in advance of this afternoon’s deadline. The Division of Physics in NSF, which includes Experimental Particle Physics, does one round of proposal review a year, and proposals are always due on the last Wednesday in September, which was today. The EPP program provides so-called “base” funding for many university research groups that work at the LHC, including mine, and that meant that today I and my colleagues were submitting a proposal for grant funding for the next three years.

Writing funding proposals is arguably the most important thing that I do as a professor. Our particle physics group at Nebraska, which is led by five professors, currently employs five graduate students and six postdoctoral researchers. Our NSF grant pays these people their (admittedly modest) salaries, and we must make sure that we get our funding to ensure that our young physicists, all of whom are doing work that is important for the success of our experiments, remain in our employ. Without this funding, it would be hard for us to carry out any research at all. Student tuition and stipends and postdoc salaries are in fact by far the largest component of our grant budget; these grants ultimately go towards the education and training of the next generation of leaders of our field. Travel expenses are another major component; it’s not cheap to get to CERN.

It is worth mentioning here that the NSF is one of the sponsors of this very Web site. I’m really quite grateful for their support, and I always try to remain aware that it is the hard-earned tax dollars of people who live and work in the United States that are supporting our work.

Writing these proposals is not easy! The NSF has some very specific rules on how proposals are to be written. Not conforming to the guidelines can lead to the immediate rejection of a proposal without review, so you need to observe them very carefully. The main body of the proposal is limited to fifteen pages of text. This limit is in place to keep the review process manageable; as a reviewer, I sure don’t want to have to read too much. But this means that we are trying to describe the past and proposed future activities of a sixteen-person research group in that fifteen pages, and it is a huge challenge to do that concisely while still conveying just what it is that you are doing. A more local challenge is actually coordinating the writing efforts of five professors. I quarterbacked our proposal this time, and I had to be very aware of how different colleagues had different, um, attitudes about deadlines.

But once we had pulled all the text together, and organized all the supporting documents, and worked out all the technicalities of the budget with the university accountants, I was able to read through the proposal and really be proud of how much our group is doing, and how much we think we can do over the next three years. You don’t always get that perspective in your day-to-day work, so it is refreshing to look at the big picture now and then. Will the peer reviewers of the proposal see it the same way? I’ll let you know sometime in the spring.

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On the Top of Spain

Wednesday, September 30th, 2009

Yesterday we tackled a special project: To climb the highest mountain of Spain, the Teide on Tenerife, with an altitude of 3718 m. Well, even though we are staying almost at sea level, we don’t have to hike up all that much: You can drive up to 2300 m, and then there is a cable car that goes up to 3500 m. Of course, hiking up is also a possibility, but we did quite a bit of that already two days ago. Plus, it is a bit annoying if you hike up for a few hours, and then you meet all the others who have taken the easy way up. The last few hundred meters to the summit, the “Pico del Teide”, is a bit more exclusive: You need written permission to go up, and only 150 people per day are permitted, to protect the summit from too many visitors. The permit also gives you just a two hour window to go to the top and back, so we had to be on time!

El Teide, the volcano on Tenerife, in the morning light

El Teide, the volcano on Tenerife, in the morning light.

We started relatively early (at least for vacation), with a beautiful view of the mountain in the morning sun. After a bit more than an hour drive, up a winding mountain road, we arrived at the cable car station, and then took our trip up to the mountain. Up there, you can immediately tell the beach tourists from the more experienced hikers: Just look for shorts and T-shirts. At 3500 m altitude it is always cold, even on an almost tropical island. Temperatures below freezing, certainly in the morning, quickly get the masses back down with the next cable car. Plus of course the thin air (thanks Ingrid for “stealing” that ideal post title 😉 ), which also comes as a shock if you are not used to this.

Going up to the Pico del Teide: Tropical island or not, 3700 m asl gloves and a hat are a good idea.

Going up to the Pico del Teide: Tropical island or not, 3700 m asl gloves and a hat are a good idea.

The hike up the last 200 something vertical meters is a bit strenuous, due to the lack of oxygen, especially since we did not really get acclimatized by sleeping at sea level. I guess the hike three days ago helped a bit, though. Up on the top, the view was breathtaking. We could see the other islands around Tenerife, and of course the whole island itself. Some of it was covered in clouds, also quite usual for an island with a high volcano in the center. Up there, you can also see that the volcano is still alive. Hot fumes are wafting from vents around the summit, and there is a strong smell of brimstone. After 20 minutes or so on the Top of Spain, plus the compulsory summit photograph, we went back down, and then took the cable car to regions with denser and warmer air.

All in all, a worthwhile trip, so if you ever end up going to Tenerife, be sure to request your summit permit in advance (can be done online, although that is not so easy to find, and all relevant pages are in Spanish…)!

My wife and I on the Top of Spain.

My wife and I on the Top of Spain.

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The new employee

Wednesday, September 30th, 2009

After six months of working at the Nikhef, the people who are paying me, invited me for their introduction day. “An informative and relaxed afternoon. You will find out the benefits of your contract, meet other new employees and lunch is served. Your attendance is compulsory, please let us know if you will be there.” I think the last sentence of this paragraph is an excellent introduction to the Dutch mindset.

In Holland we have different kinds of forbiddeness. Most things are legal: biking, eating, normal things. Some things are illegal: please refer to the Dutch law for an extended list of illegal actions. But there is also a third category: things that are illegal, but allowed. This would include the use and owning of cannabis, prostitution and riding a bike on the wrong side of the street. It is now easy to spot a tourist in Amsterdam’s city center: they wait at the sign “do not cross”. To the Dutch such a sign only indicates: “please pay extra attention when crossing here.”

This makes the rather paradoxical statement that you have to be there AND announce your attendance a little less confusing. To me “obligatory” is as binding as “informative”. If you ever visit the Netherlands, don’t take us to seriously, we don’t do that either 🙂

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Shift drifter

Wednesday, September 30th, 2009

It’s morning, late September, in the ATLAS control room. We’re coming to the end of a long overnight run and
I have just started a shift. It really is fair to say that of the few of us currently in the control room, the gentleman
doing the cleaning is the most active. He has cleaned every desktop thoroughly and forced each and every
one of us out of our chairs so that he can sweep the floors, with vigor. I’ve been up earlier than usual for
quite a few days now. Day shifts start at 7am and so for me that means about a 5.30am wake up time in order
to leave sufficient minutes to consume the gallon of coffee necessary for me to be considered safe on the roads.
The lady who runs the patisserie across the road from my house (one of the best in existence – the bakery I mean
not the lady, who is pleasant don’t get me wrong, but probably not ‘one of the best women in existence’) is starting
to give me strange looks as I’ve been waiting outside for her to unlock her doors for the last couple of days. I’m
pretty sure she knows me as “that guy who asks for un baguette and NOT une baguette”, something I’ve been
skillfully avoiding recently by only purchasing multiple baguettes and hence avoiding the need to memorize the
gender of my baked goods. It was cold today and surprisingly busy as I sped towards point 1. Now I’m here,
morning shafts of light start to break in through the mighty windows behind me. I’m sat at the pixel desk
(for those of you who know the ACR) watching my four screens do very little as the run keeps going, we’re at
12h 8m and, lets call it 45 secs. The cleaner is now putting the rest of us to shame by vacuuming the floors,
leaving behind an air of guilt at the apparent lack of actual work being accomplished in the control room.
The plan for my shift is to:
a) If anything starts flashing red find out why it’s flashing and red.
b) Start doing some calibrations and try to ensure I don’t have to do a).
c) Wait for something to happen

A lot of us take shifts for reasons other than the actual act of shift-taking. In a smooth running, ideal physics
data-taking world, the shift allows one to get on with some real work. Imagine being stuck in a room for 8 hours
with nothing much to do, it affords one the opportunity to get on with all manner of work. On a good
data-taking shift there is little to do and you can get a lot done, which is great. Personally I kind of enjoy the
problem solving of things actually happening and having to respond to the a)’s in my tongue-in-cheek shift
plan above. This afternoon should leave plenty of problem solving time as we work on changing the rate
of data-taking, check for things going busy, disable modules ‘losing clock’ and work on upgrading
formatters. Fantastic stuff!

Even though we’d really like to get a lot of work done on shift there is always the possibility that you might goof off
for a bit and stop checking your panels and instead surf the web, write some emails….or work on a blog entry.

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Back at the Home Institute.

Tuesday, September 29th, 2009

I’m in CMH airport in Columbus now, waiting for my plane back to Chicago, Fermilab, and home.

I really should have cut this closer, since I have an hour to go, and I left 15 minutes early from a really great colloquium by Sean Carroll at OSU.  He was talking about topics from his yet-unreleased book, From Eternity To Here,  specifically the arrow of time.  In honor of this, I’m writing this post chronologically backwards.

The talk was fun, and you can see the slides from it here, although you miss the humor of him reading scrawled hate mail from a 10 year old out loud in a serious tone.  The author of said hate mail was irate about the possibility of his universe fluctuating in and out of the vacuum or some such.  In general, the talk was full of historical anecdotes and broad conceptual strokes, which I think is a great tack for a talk to a physics department.

The earlier part of today I spent working with the two grad students from my group who are working on CDF, and running an early stage meeting on developing software for a Higgs search I work on.  Right now, there are a couple of distinct analyses going on at CDF that look for a Higgs bosons which are produced in the same collisions as a W boson.  These separate searches share a lot of the same methods, but they intentionally differ in the way that they estimate the likelihood that a given event is from a Higgs instead of other, less exciting processes.  The problem is that these separate studies were developed by separate people using separate code, so that the other steps of the search are similar, but not really identical.  Some of the differences are trivial, some are just matters of taste, and some of them are subtle and generate a lot of debate.  They are all pretty robust and reliable analyses, but it would save a lot of effort and make things like combination studies go way smoother if we standardized some of this.

Last night I went out in Columbus with a few of the grad students from my group and some of their friends.  It really made me miss being in a college town, since the Tevatron is really out in the suburbs.

Monday was the whole reason I made this trip:  The Department of Energy Review.  My salary, and a large fraction of High Energy Physics in this country is funded by the DOE.  My advisors were given a grant to do particular research, including a chunk for postdocs like myself, and, once a fiscal year, they send someone to review the progress of a group and make sure they are meeting the goals of the grant.  The reviewer in question, so I’m told, is a physicist originally from SLAC.  I can’t confirm this myself, since I didn’t speak to him except during my presentation.  The presentation was actually pretty fun.  I work for a good group who has a long history at CDF and top/Higgs searches, so the presentations were full of accomplishments and big hopes for improving our analyses.  No telling how the funding will go, since I’m pretty sure the DOE budget itself isn’t really settled.

While I work for two professors at OSU, I spend most of my time at Fermilab keeping our part of CDF running, and working on analyses.  I’ve only had this postdoc for eight months are so, and, not counting the interview, I think I’ve been in Columbus only four times.  Luckily, there’s a good set of flights that I normally come in 8am one day, work till 7pm or so, crash at the closest hotel, back in the office at 8am, and fly out at 7pm or so the following day.   Its a bit draning, but it gets things moving the way that video conferencing whishes it could.

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Physics is like…

Tuesday, September 29th, 2009

A lot of topics in physics are explained through analogy. While objects rolling down a ramp or colliding are phenomena people have experience with every day, quantum mechanics and relativity are not part of our daily awareness. They are introduced, conceptually, through descriptions we can understand but that don’t fully encompass what is going on. But seeing as “time slows down” and “the cat is both dead and alive” are hard enough to figure out, the analogies are a good place to start.

Non-quantum cats (in Erice)

Non-quantum cats (in Erice)

Particle physicists spend a lot of time on analogies, likely because our work is so far from what most people deal with daily and requires relatively advanced math. While I think neutrino mixing is ‘straight-forward’ and easy to understand from the math, those equations won’t help my non-physics family and friends. How then, can we explain it? At the International Nuclear School in Erice, Prof. Christian Weinheimer presented an experimental parallel with polarized light. A laser beam is polarized, passed through a birefringent crystal, and then split to have each polarization measured with photodiodes. While his talk was geared towards neutrino physicists, the hope was that we could take the technique back and present it to advanced high school and early university students. I’m not sure how many high school students in the US understand polarized light, but it should certainly work with early university students. Not only is the mixing conceptually similar, but the math works in a very similar way as well.

I find myself attempting to explain my experiment and the physics I work on to people who have not had university (or even high school) physics. I think I have finally come up with a good analogy for the design of EXO-200, a time projection chamber. While scintillation light and ionization are not familiar to many people, lightning is. When a decay occurs in our detector, it is like a flash of lightning. The light we see is immediate, followed some time later by the ‘thunder’ (for us, ionization). By measuring the difference in time between the ‘lightning’ and ‘thunder’ we can tell how far away the decay occurred. The biggest flaw in this is that normally light gives information about how big and what orientation the lightning strike was, while thunder only gives a rough direction. For us, it the other way around – the light can’t tell us much about where the decay way but the ionization (‘thunder’) does.

Hopefully I will improve my own physics analogies over time, or hear good ones that others have developed. My recent favorite is comparing dark matter to the unsocial people at a party. Not only does it capture the physics – freeze out, unseen interactions – it also brings to mind the anti-social stereotype that haunts physicists. This should make the analogy easier to remember! My current quest is to find a good analogy for the Taylor Series Expansion. Given enough time and something to write on, I can explain it to someone who knows what the sine wave is. I haven’t found a good way to explain it quickly – to cashier at a store – or to someone who doesn’t know about the sine wave.

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Hard-cooked Eggs

Tuesday, September 29th, 2009
What would a summer vacation be without a beach? The black sand is a design mistake, though, at least for the feet...

What would a summer vacation be without a beach? The black sand is a design mistake, though, at least for the feet...

Finally: Vacation! More than a week of, with (almost) no work. Well, as you can see from the fact that I’m writing this entry, I am connected to the Internet (actually, a criterion when we selected the place to stay). That means that I’ll also read email, and work a little bit on the side, as long as my wife does not look too disapproving 😉 . For example, I am missing the Linear Collider Workshop of the Americas, which is taking place this week in Albuquerque. But as you have no doubt realized by now, there are so many meetings to go to, you just can’t make them all. But nobody of my group can attend this one, so Felix from DESY is giving a talk on my behalf to present our results… Thanks a lot! But still, I have to prepare the slides for this, but that is done now.

So, where am I? My wife and I are spending 10 days on Tenerife, one of the Canary Islands west of northern Africa in the Atlantic Ocean. A beautiful place, with lots of different things to do. Of course there are beaches, but, since this is a volcanic island with mostly black lava rocks near coast, most of these beaches have black sand. Looks cool, but hurts like hell if you walk over the beach barefoot! As a volcanic island, it also has a volcano (obviously), the highest mountain of Spain, and the highest mountain in the EU outside of the Alps. Which is a good thing, since laying on the beach all day is not really our thing. To get used to some hiking again, and to the altitude (after all, our last trip to the mountains was a while back, and I still owe a post about that…), we paid the “Huevos del Teide”, the “Eggs” of the volcano a visit on Sunday. That is a good 5 hour hike, all above 2000 m above sea level, up to an altitude of 2750 m. And the volcanic eggs, hard-cooked, no doubt, really look cool, on the light brown slope of the mountain. They got formed during the last outbreaks of the volcano, a few hundred years ago, sort of like a snow-ball, but rolling down on a lava stream instead. Toppling one over did not quite work, as you can see.

Toppling over or cracking a hard-cooked volcanic egg: No easy task!

Toppling over or cracking a hard-cooked volcanic egg: No easy task!

Telescopes on Tenerife: Physics is everywhere!

Telescopes on Tenerife: Physics is everywhere!

As a side note, the Canary Islands are far from physics-free. Of course, there is no big accelerator lab here, so not the kind of stuff I’m doing, but the atmospheric conditions here are phenomenal: Incredibly clear air due to the very low humidity at higher altitudes (something like 25% relative humidity, which is dryer than most deserts), and essentially no light pollution. So, on several of these islands there are telescopes. The one Im most familiar with is MAGIC, an Airshower Cherencov Telescope on La Palma, an island west from here. But, as the picture shows, there are also some optical telescopes here on Tenerife… So, physics (and astronomy, of course 😉 ) is really everywhere…

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And now another installment of “Symmetry in Physics.” Recall that in part 1 we introduced the idea of symmetry and mentioned the symmetries of spacetime, such as rotations or translations. These symmetries are all ‘continuous,’ in the sense that you can rotate/translate by any arbitrary amount. Now we’ll introduce some of the discrete symmetries of spacetime, meaning that the symmetry only acts by a certain amount. In particular, we’ll focus on symmetries where one flips the sign (‘swaps the polarity’) of an object that can take two values. It turns out that this will be intimately linked to our notion of antimatter.

The spacetime symmetries we discussed in the previous post can be expanded to include three discrete symmetries: parity, charge conjugation, and time-reversal. It turns out (rather surprisingly) that physics chooses not to obey these symmetries, and this act of rebellion allowed the universe to develop interesting things like galaxies and life.

Parity

Parity is the symmetry where we reverse all of our space directions. For example, if we draw a coordinate system (x,y,z) in space, a parity transformation gives us a new coordinate system (x’,y’,z’) drawn below.paritytransform1

What’s the difference between these two coordinates? The first coordinate system obeys the ‘right hand rule.’ If you point your right hand in the x direction and curl your fingers towards the y direction, then your thumb will point in the z direction. The parity-transformed coordinate system, on the other hand, does not obey this property. It is, in fact, a left handed coordinate system. Thus a parity transform essentially swaps left and right.

Does this remind you of anything? One of my favorite puzzles as a child was the question of why a mirror reverses left and right but not up and down. The answer is that the mirror enacts a parity transformation. It reverses the forward-backward direction while maintaining the other two axes. For homework you can convince yourself that this is equivalent to our definition of ‘parity’ above. (For more discussion see this Richard Feynman video clip.)

Parity is a useful quantity when describing spinning particles: the parity transform of a particle spinning in one direction is the particle spinning in the opposite direction.

spin1

We might believe that nature obeys parity symmetry, but we’ll see that this is actually not true. Biologists might have already guessed this since the amino acids which make up proteins in cells are all left-handed.

(In fact, when the eminent theorist Wolfgang Pauli heard that Chien-Shiung Wu constructing an experiment to test whether the weak force obeys parity symmetry he scoffed that it was obvious that the answer had to be ‘yes.’ The entire community was shocked to find out that indeed, parity is not a good symmetry of nature!)

(more…)

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What the Q do we know (part II)

Monday, September 28th, 2009

Einstein was right. We are pretty sure. The Universe is filled with massive things that interact by the gravitational force. Good. The Standard Model is predictive. It can be seen from the math in the Standard Model that there must be four particles that carry the Electro-Weak force. This seems true. Good.

The Standard Model is a quantum field theory. In quantum mechanics statistics play a central role. Objects have some probability to be in certain point in space-time carrying a mass within some mass-range and showing one out of many expected behaviors. Just like humans, in a way. The Standard Model predicts that these objects interact in particular patterns. By studying the different behaviors of an object, we can find out what particle we are dealing with and test the model.

The probabilities for a particular interaction to occur are only predicted in terms of the other parameters of the model. “If A happens ten times, B happens twenty times.” The numbers themselves need to be measured in experiments. The Standard Model has proven itself very believable when it predicted the Z-boson, which was later on explicitly measured in Geneva. A predictive model seems better than one that only explains Nature afterwards. You rather know the timetable of tomorrows than yesterdays trains.

But the Standard Model only works so well as long all the masses of the objects in the model are set to zero. But Einstein tells us mass exists in the Universe. And the Standard Model explains the fundamental particles of all. This does not go together. You could claim that we need to reinterpret General Relativity and set all masses in the Universe to zero. The outcome would highly interest me. No more diets ever! But physicists have tried to expand the Standard Model so that masses are allowed. This extension can be done and leaves the model unchanged enough to still explain Nature as far as we know it now. One iny-winy-tiny problem needs to be solved: the particle that is predicted in this extension, aka the Higgs-boson, needs to be found.

By the time it is found, don’t trust your physics friend who claims that (s)he is a little disappointed that Nature is as boring to do what we thought: we will be very relieved. We have no clue how to catch nature into formulas without the Standard Model and Higgs particle.

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Where to Live Around CERN

Sunday, September 27th, 2009

cern-site

The main site of CERN, where most offices are, is a mile long and straddles the border between France and Switzerland (Suisse).

Some nearby villages students/post-docs choose to live in include:

  • Saint-Genis-Pouilly, France – pop 7,000
  • Thoiry, France – pop 4,000
  • Meyrin, Switzerland – pop 21,000 (city on lower right of map)
  • Ferney-Voltaire, France – pop 7,000 (not shown)
  • Geneva, Switzerland – pop 190,000 (also not shown)

There are advantages and disadvantages to living in each country.  (more…)

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