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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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.

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.

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!)

Continue Reading »

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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.  Continue Reading »

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Rumors spread like wild fire for wee little grad students (1st and 2nd years) and one thing we would chat about around the chalk board was that grad students for some “unknown” reason disappear during their third year in grad school. Sometimes they return, sometimes they don’t… and they’re never seen or heard from again. What happens during this time? Do they turn into trolls… get eaten by trolls… go off to fight trolls… (and why am I talking about trolls)? Having just finished my third year, I thought I’d reflect a little on this.

Ha! you caught me, I just liked this picture

It’s an important time in any young grad student’s life because you’re growing into a little scientist. Like teens finally getting the keys to drive, you’re finally out on your own… in that your parents still mostly cover for you, but now you can drive yourself to school.

students first keys

You start to answer your own questions about research, realize that sometimes you have to figure things out for yourself, and that sometimes your advisor isn’t going to answer his/her email as soon as you’d like.  It’s weird because in essence we’re in 19th grade (20+ years of school) and we’ve done pretty well with that, but research is different. There’s no more 8 am classes to go to or tests to study for. And finally you also are able to help other people – those now pesky younger grad students who joined the group a year or two after you did.

I have to give the disclaimer that I’m speaking mostly for myself and the friends I’ve spoken to, but at least in my circle this is a pretty common. I know my postdoc buddy, and fellow science blogger, thought that my naiveté when I first arrived at CERN was (I hope) endearing. I eventually learned better ways to fit functions, found more efficient ways to write code, updated my operating system (yeah, got lots of bad times about that), and had more realistic ideas about experimental research. Although I still have child-like innocence to shed before I become a grizzly post doc (probably a couple more years worth), I hope one day I too will be a wise learned scientist who with a mere glance can force code to compile, grants to be granted, and students to work harder.

-Regina

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One of the advantages of being an experimental particle physicist is that we somehow enjoy certain flexibility in our work schedule.   It is not unusual at all to work very long hours even during weekends for extended periods of time (graduate students can tell you all about it), or to literally run on coffee (or anything that has caffeine) because you haven’t slept more than a few hours in a few days. But once in a while, if you are lucky enough to have had cool supervisors like I have, it is possible to escape for an extended weekend without feeling too much guilt.

I did so last weekend, I went to the Czech Republic to attend the wedding of one of my best friends.  While celebrating in the beautiful countryside, where the wedding took place, and after a couple of  Meruňkovice shots, we started planning our two-day visit to Prague.  Being Czech and a very good particle physicist,  my friend knew something that I was not aware of.  He told me that Albert Einstein had taught in the German University in Prague.  In fact, he later showed me a memorial plaque outside a house in Prague’s Old Town Square that reads: “Here in this salon of Mrs Berta Fanta, Albert Einstein, Professor at Prague University in 1911 to 1912, founder of the theory of relativity, Nobel Prize Winner, played the violin and met his friends, famous writers, Max Brod and Franz Kafka.”

At any modern particle collider, where gravity effects are negligible, special relativity is the pain quotidien.  However, at the LHC, there are many theories that predict scenarios where gravitational effects are important, in which case we would be able to learn more about the old mystery of  how to reconcile vastly tested Einstein’s general relativity with quantum mechanics.  Most of these scenarios (string-theory inspired) involve the presence of more than two additional space dimensions in our Universe, not large enough to solve the sock in the dryer mystery, but rather tiny, on the order of a millionth of a meter or smaller.   The leakage of the gravitational field in the extra volume could justify gravity’s marked weakness compared to the rest of the forces in Nature.  At the CMS experiment we are preparing to test such scenarios among other interesting physics.

In Prague, good old Al found – in his own words – “the necessary composure to give the basic thought of the general theory of relativity (1908) step by step a more definite shape…” , and I can certainly understand why now.  Not that I will ever experience the enlightenment Einstein found there, but after visiting beautiful Prague and enjoying the warmth of its wonderful people and its exciting culture, I feel energized, very energized, ready to continue our extraordinary adventure at the LHC, maybe a quantum-gravitational one!

Edgar F. Carrera (Boston University)

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Fermilab recently launched a new web site describing the idea of a muon collider. Why think about a future collider when we haven’t even started using the LHC yet? Because it takes a really long time to design and build one. The LHC was conceived a few decades ago, and the LHC project was approved in 1994, fifteen years ago. Also, Fermilab is soon going to shut down its Tevatron collider that has operated for almost 30 years, and is planning for its future.

I find the idea of a muon collider very intriguing. The idea is to collide positive and negative muons together, as opposed to colliding protons together as will be done at the LHC. A muon collider would be well suited to precise measurements, whereas the LHC is more of a discovery machine. This is because the protons colliding at the LHC are made of other particles called quarks and gluons, and it is those particles that actually collide in the LHC. So a collision of protons is really a collision of many quarks and gluons, which can be quite a messy thing to try to understand. A muon collider would collide muons only, so the collsions would be “cleaner” in the sense that there are fewer particles colliding at once. This makes understanding what happened in a collision easier to understand.

A muon collider would be a great tool for precisely studying whatever new particles are found at the LHC. Another option for a precise instrument is an electron collider, and there are proposals to build electron colliders as well. A muon collider has the advantage of being much smaller (a circle 2 km across instead of the proposed 30 or 50 km in a straight line proposed for electron colliders).

However, the technology necessary to build a muon collider is still being developed, whereas the technology needed to build an electron collider is already well advanced. But assuming we discover some interesting new particles at the LHC, building an electron or muon collider to follow up would be a great idea. So when will this happen? In the case of the muon collider, the schedule estimates I’ve seen currently put first collisions around 2028.

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Doing a quick poll of graduate students in our department showed the following:

• Atomic Physics: 5/10 grad students are married (2 of those have kids)
• Particle Physics (CMS group): 1/10 grad students are married (none of those have kids)

Most likely, this difference is because “Atomic” physics involves small, table-top experiments, while “Particle” physics involves large experiments located on another continent.

This leads to other differences as well: 3 1.5/10 Particle physics grads above are in long-term, long-distance relationships (they live at CERN), meanwhile, none of the grad students in Atomic physics are in a long-distance relationship (their experiments are conveniently located in the same city).

What is it like at your university, or your research group?  Is this just a statistical anomaly, or is there really far fewer married graduate students in particle physics than in other research areas?

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Your humble correspondent hasn’t had a chance to write much lately, as I have been dealing with an unfortunate confluence of events that require my attention. I’ll try to catch up on some of these events over the next few weeks/posts.

In a previous post, I mentioned our engagement in research on future silicon pixel detectors. This is funded by a rather interesting National Science Foundation grant that I’m on from their Partnerships in International Research and Education program. Like the title says, the purpose of the program is to create partnerships between U.S. and non-U.S. institutions to create research and education opportunities that have a significant international component. This program is very competitive, and we were lucky to be awarded a PIRE grant in 2007.

We are part of a consortium of five U.S. schools — UNL, University of Kansas, Kansas State University, University of Illinois-Chicago and University of Puerto Rico-Mayaguez — that is working with the Paul Scherrer Institute in Switzerland and ETH, the Swiss Federal Institute of Technology in Zurich. We send graduate and undergraduate students on an all-expense paid trip to do research work at PSI for the summer, and to take classes at ETH during the school year. The scientific goals of the project are to do the R&D work for the next CMS pixel detector, and to learn as much as we can from the talented PSI group. The broader educational goals are to give the students the opportunity to engage in a great learning experience abroad.

The PIRE group holds an annual workshop, and this year it was our turn to host it at UNL. We “only” had about 25 people coming to visit us for the two days, but my colleague Aaron and I still had a lot to do to take care of all the logistics and put together the agenda and so forth. After all that, it went pretty well. There is a lot of activity on the project, but it’s hard to get a view of how it all fits together unless you have some meetings like this. When you sum up all the little summer projects that students have done, it starts to look pretty impressive. There have been a number of published papers and conference presentations on the work. Perhaps the nicest part was hearing about the students’ experience of living, working and studying abroad. Everyone said that it was a real eye-opener; having the chance to be immersed in a foreign culture teaches you a lot about your own. We’ve only had a few students take classes at ETH so far, but they have been wildly enthusiastic about their experience — they found the classes challenging but satisfying, and got a lot of great support from ETH staff. After hearing all that, I definitely want to track down more students who can benefit from joining this project.

But one of the best things about the workshop is that the collaborators from the other schools are a nice group of people, and we really enjoyed getting to sit down face to face and talk about our work and the rest of life. I’m already looking forward to our next get-together…even if it is going to be in Manhattan, KS!

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Inspired by Regina’s excellent post on the CERN accelerator complex, I thought I’d give you some fun facts about the LHC (in “human units”).

1) What does 7 TeV beam energy mean?

Please look at Wikipedia for a discussion of units. Briefly, 1 Joule is the energy of a 1 Kilogram mass moving with a speed of 1 meter/second (1 J = 1 Kg * (1 m/s)²). In particle physics units, it is about 6*10¹⁸ electron volts, i.e., 6*10⁶ TeV.

When operating at design parameters, the LHC will have two beams of protons, where each beam consists of ~2800 individual bunches, and each bunch contains ~10¹¹ protons. Each proton will have energy of 7 TeV, so the energy of each bunch of protons is ~ 7*10¹¹ TeV, i.e., 110,000 Joules (or 110 kilo Joules).

A bullet fired from a rifle typically weighs 4 grams, and can have speeds of up to 1000 m/s when it leaves the barrel. This corresponds to an energy of about 2000 Joules, i.e., roughly 1/55 the energy of one bunch of protons. Anti-tank shells (used in WW II) had energies anywhere from 150-800 kilo Joules.

So, it is crucial that the beam does not hit something that it is not intended to hit! (BTW, I have not included the energy stored in the magnets, which is a whole different story, and is many times larger).

2) How cold is the LHC?

The magnets in the LHC are superconducting. For this, the magnet mass and the wires carrying the electrical current (which generates the magnetic field) have to be cooled to about 2° K, i.e., -271° Celsius, or -455° Fahrenheit; the refrigeration plant uses 50,000 tons of liquid Helium.

By studying the Cosmic Microwave Background, which is a form of electromagnetic radiation filling the universe, astronomers have deduced that the current average temperature of the known universe is about 2.7° K.

This makes the LHC the coolest place in the Universe! (Well, not quite. Some atomic physics experiments attain much lower temperatures – thanks to Tim for pointing this out).

3) How about those magnets?

To keep the proton beam circulating in the accelerator ring at 7 TeV, we need very strong magnetic fields. For this purpose, the LHC has 1232 dipole magnets, each of which is 14 m long, weighs about 35 tons, and the required magnetic field is generated by passing about 11700 Amps of current through 5 Km of superconducting wire.

Then there are about 7066 magnets that focus the beam, and otherwise correct the path of the proton beam. For instance, if nothing was done, a proton will “fall” down due to gravity and hit the beampipe after travelling a mere 850 times around the ring (in one second, it goes around the ring about 11000 times).

To learn more, please take a look at this web page and links therein.

– Vivek Jain, Indiana University

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One of the reasons why physicists often wax poetic about the beauty of physics is that so much of the field has based on symmetry, and humans find symmetry beautiful. But it is partly because people have an intuitive sense of what symmetry is that there aren’t many attempts to really explain the central role that it has played in theoretical physics.

Over the next few posts I’d like to go over some of the ways symmetry shapes how we think about physics. I’ll be necessarily heuristic, but I hope to give an honest sense of what physicists mean by symmetry and why it’s been the primary guiding principle in theoretical particle physics for the past 50 years.

Already at an intuitive level it’s probably not hard to believe that symmetries constrain and simplify things. If I tell you to draw a blob, you might draw any unexpected shape. On the other hand, if I told you to draw a blob with rotational symmetry, you are constrained to draw circles:

Similarly, if I tell you that a theory of gravity is spherically symmetric, then you know that the gravitational potential only depends only on the radial distance from the source and is independent of angular information. If you calculate the field at some distance r, then you know that the potential is the same for all other points of the same distance r. [A more advanced discussion: because the force is proportional to the change in, or gradient of, the potential, you know that the force can only be in the radial direction.]

The mathematical language of symmetry is group theory. A discussion of group theory would take us too far astray, but I heartily recommend that young physicists make a point to learn group theory when they have a chance. (The earlier the better, especially since it doesn’t require much fancy math background.)

Actually, this is a lesson in having a broad background. Murray Gell-Mann, one of the heroes of American physics and co-developer of the quark model, actually re-invented group theory for himself when trying to describe the spectrum of hadrons discovered in the 1960s. He called it the eightfold way (he was very good at naming things) and only later realized that there already existed a mathematical language for his method.

Symmetries of Spacetime

Let’s talk about the symmetries of space and time.

• Translational symmetry: the laws of physics are the same everywhere and at all times
• Rotational symmetry: the laws of physics don’t depend on how we orient our coordinates
• Boost symmetry: the laws of physics don’t depend on what inertial frame we’re in. In other words, the laws of physics for someone standing still are the same as for those who are moving at a constant velocity.

Note that I didn’t say that physical observables obey these symmetries. I can survive on the surface of the Earth but not at the sun’s core. Gravity tells me that “up” and “down” are two very different directions. And if I stand still I’m fine but if I’m moving at a constant velocity I’ll eventually run into something like a building or a tree.  Our universe clearly doesn’t obey the symmetries listed above. That’s fine.

The point is that the laws of physics do obey these symmetries. You can think of “the laws of physics” as a set of fundamental laws governing the dynamics of nature. Even though nature itself isn’t symmetric (that’s a whole different story), its rules are. Classically, the law “F=ma” holds no matter where you are, when you measured it, and how you oriented yourself. Sure, the numbers might change depending on how you’re oriented, but the relation between the numbers remains true.

What does this all mean for particle physics? A particle is a particle is a particle! Suppose I had a particle. Let me draw it as a penguin (don’t ask me why). The symmetries of spacetime tell me that if I put the penguin somewhere else, or if I rotate it, or if I give it a nudge so that it’s moving at a constant velocity… then the penguin is still the same penguin that I started with. I don’t need a new framework to describe “penguin in motion rotated by 30 degrees” than I would to describe the original penguin.

This statement is so ridiculously trivial that it probably ends up sounding more complicated than it is. Obviously we know that these are all versions of the same penguin, I’ve just moved them around in ways allowed by the symmetries of space. But ‘technically’ they are all different penguins: one is tilted one way, another one is moving… if we were very, very naive we’d think “these are different things — why are you calling them the same?” The answer is that spacetime is symmetric.

[Let me say this in a different way: the symmetries of spacetime are so deeply ingrained in us as infants that we don't even think about a penguin as being different from a penguin tilted on its side. Technically, though, they are different: one is tilted! So without any prior input, why should physics treat the tilted penguin the same way as it treats the original penguin?]

Okay… still with me? Good. Now go back and re-read the last three paragraphs with the word “penguin” replaced by “particle.” The take-home message is this: symmetries allow us to treat [naively] different objects as the same object.

Now we’re starting to get somewhere.

Before we go any further, let me stop and drop some fancy words for more advanced readers. For others, just think of these as words that you can use to impress your friends. The “full” meaning of these words is based on group theory, but we’ll try to give a sense of what they mean. The symmetries of spacetime are collectively called the Poincare symmetry. Particles are irreducible representations of the Poincare group, meaning they change in well-defined ways under Poincare symmetry. The subset of Poincare symmetry dealing only with rotations and change of inertial frames is called Lorentz symmetry. It is formulated to automatically obey the symmetries of Einstein’s special relativity (e.g. effects like time dilation and length contraction are already “built-in”). Quantum fields, which “give rise” to particles, are irreducible representations of the Lorentz group. [If you feel a little lost, don't worry; this paragraph is just an aside.]

Epilogue, Part 1

Unfortunately, this was probably enough of a bite-sized (blog-sized) discussion for today. In terms of learning ’sexy new truths about the universe,’ we haven’t gotten very far. What we have done, though, is lay down some foundational principles about the role of symmetry in physics. In summary,

• Symmetries simplify things by constraining their form (e.g. a rotationally symmetric blob must be a circle)
• Symmetries allow us to identify “naively different” objects as really being part of the same object

In our next post we’ll follow these symmetry principles and consider the discrete symmetries of spacetime. Without spoiling too much ahead of time, we’ll see that we are naturally led to the idea of antiparticles.

-Flip

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My close friends (and now blog enthusiasts) are familiar with my favorite part of a pair of pajamas. They’re a pair of green flannel pants with monkey faces on them, lovingly referred to as my “monkey pants”. They look something like this:

Upon arriving home from work – most typically in the winter, I’ll relax by slipping into these comfy pj bottoms. Once this happens I’m not leaving the house. I’m already in comfort mode, and there’s no going back into restricting jeans. So as great as these pants are, why am I telling you all this? I promise I’m not a part of the vast monkey pants lobby.

One of the best changes about being back in New York is attending meetings at CERN. Since ATLAS is a global collaboration most of our meetings have access via the CERN phone system or the internet. This is now how I access all the usual meetings I would attend a few months ago. Lucky for me, most meetings at CERN are held in the afternoon (so that the North American colleagues don’t have to call in at 2 a.m.). They usually fall from 9 – 11 a.m. I’m usually on campus for most meetings. Nothing really special about this scenario… However, every once and a while a meeting  falls at 7 or 8 a.m. in New York, I’ll attend the meeting from home. Which means…. meetings in my monkey pants!

Could it be any better? Maybe with one of these…

Unfortunately last time I checked, there were no complimentary sundaes from the LAr group. But with that exception meetings in my pjs (with no guilt about it) are a big bonus to being back in the US. Until next time

-Regina

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Comment vas-tu? Je vais bien!

You’re driving along in France and suddenly you see this sign on the right side of the road – would you know what to do? Are you comfortable enough with French to get around safely?

If you are planning to visit CERN or the Geneva area I recommend learning at least a few basic french words. Too many Americans show up either not knowing or not comfortable saying simple things which you will hear or need to use within a day of your arrival. Continue Reading »

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Howdy! LHC fans, and welcome to my US LHC blog area.  It is a great pleasure for me to have this opportunity to communicate what we are up to at the LHC from a more personal perspective.  I hope you enjoy it!!

This is my first post and so I thought it was a good idea to talk about things related to my first HLT (High-level Trigger) expert shift.  It was a few weeks ago when the HLT cell phone rang in my pocket for the first time with a phone-call from the CMS control room.   My plan of attending a French lesson in Geneva later in the evening suddenly changed for a more exciting one. There was a problem with the HLT system and, as the expert on-call, I needed to figure out the nature of the problem very quickly.  Before telling you about the problem, let me try to explain a key feature of our trigger system: regional reconstruction.

Imagine a friend of your identical twin brothers hands you over two pictures of his group of friends. One of them is in front of the Pantheon in Rome and the other one in front of the façade of the Pantheón in Paris. Now, you have never been in either city and you know almost nothing about these historical sites (they look almost the same to you), but he challenges you to identify the cities in one minute. Since you are clever and you know that only one of your twin brothers was able to make it to these two cities at a time, you rapidly identify them and correctly associate the cities. Your friend is very impressed!

Now, imagine the same friend hands you over the same two pictures but made into finely-cut jigsaw puzzles and he challenges you again with the same task. You have only one minute to identify the cities but now the faces of your brothers may not look as identifiable as they were before. However, you remain clever and take the whole minute to try to reconstruct the face of who you think is one of them in one of the photos. You start by a “seed” (a puzzle piece containing your brother’s eye, for instance) and then you try to arrange the pieces around the seed to quickly take a look at his face. The task was not easy because there were many pieces, but you were fast enough to complete one face in one picture and, therefore, identify the cities correctly once again. Your friend is shocked by how smart you are!!

The electronic signals of the millions of independent channels in a modern particle detector are like jigsaw puzzle pieces of a picture of a collision. As there will be billions of them happening every second at the LHC, we use a system called trigger in order to select only the interesting collision “photos”. In CMS, once first beam collisions arrive, we will not have enough time to look at the whole collision photo, hence,  similarly to the analogy above, we put together just a couple of “particle faces” (regional reconstruction) using “puzzle pieces” from one or a few sub-detectors in order to be able to say (or not): “Yes, I recognize this face (I have seen it before), I will be interested in this picture, let’s keep it; we can put all the pieces back together later to see who else was in it and what the background was like (full reconstruction)”.

The problem I had to handle, after receiving the phone call, had to do with the reconstruction of some of the “faces” in our pictures of cosmic rays data taking a very long time and clogging our system.  What makes it very exciting is that, in case of a problem with any subsystem in the detector, an on-call expert needs to react very fast, usually under a lot of pressure.  This is because if we stop taking “photos” for any reason, we might miss the “kodak” moment of a lifetime: a black hole, a Higgs boson, a supersymmetric particle, or any other exotic event.   We use cosmic data to better understand our system and to prepare for beam collisions.

We will be ready at CMS for our ultrafast photography adventure!

Edgar Carrera, Boston University

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I am back after a week’s trip to CERN. It was a productive week. I gave a talk on the work I have been doing and received valuable feedback in the sense that some of my results were met with a bit of skepticism; it took me a day of work to produce more plots, but I think I was able to address these concerns. I also attended the SUSY group meeting to see what people are up to; see Seth’s note (and search for Supersymmetry) or Wikipedia (although I don’t know what they are talking about when they say that “there is indirect evidence for SUSY”). I had a lengthy chat with one of my colleagues on how to understand Missing Energy in events containing energetic top quarks, which, if not understood, can contaminate the signal due to SUSY, thus leading to a false positive; we came up with some ideas on how to study this particular issue. Once I am closer to finishing my current project, I will start to look into this. I had spent part of the summer working with an undergraduate student (through the Research Experience for Undergraduates Program) learning about Missing Energy, so I am prepared.

It was not all work, however! A cousin recently moved from Singapore to Geneva (to work at the World Wildlife Fund), and I spent some time with him and his family; I hadn’t seen them in years. After the weeklong meetings, I took the train from Geneva to Frankfurt, where I spent a couple of days with my sister before flying back to the US. Trains in Europe are not exactly cheap (~ $180 for a one-way ticket), but they are very comfortable and punctual; we left within a minute of the listed time, and after six hours, which included a change of trains in Basel, arrived at the scheduled time (the airline industry could learn a few things from them).

Notwithstanding some of the perks of going to Europe, traveling is a pain. You have to deal with lines at security and immigration, layovers and delays at airports, being crammed into steerage (aka Economy), missed connections¹, jet lag, lack of sleep, a paucity of vegetarian food, to name a few things; I don’t think I eat as much pizza or French fries as when I am at CERN! From my house in Bloomington, IN to the hostel at CERN takes anywhere from 14 to 20 hours; it is probably longer for people coming from the West Coast. It would be really nice if we had Mr. Scotty to “beam us up”!

– Vivek Jain, Indiana University

¹ Once on the way back from CERN, my connecting flight from Newark, NJ was cancelled due to weather related problems. It took me another 30 hours to get back to Indiana; this included an overnight stay in a motel in the middle of NJ where the view was a dug up parking lot, waiting unsuccessfully to go on standby, finding a seat on a flight from Kennedy airport and making a mad dash by taxi ($130) only to be delayed by a traffic jam on the Belt Parkway and missing this flight; luckily, I found another flight that left a few hours later.

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Since the workshop in Leysin, I’ve been in the process of moving back to New York. Why move back now, you may ask? It’s a very typical story. I thought a long time about whether or not I wanted to actually blog about this. I decided to go ahead only because it’s an interesting problem that I haven’t quite figured out how to get to work out. I’ve heard it called it the “two-body problem” – which gives homage to something freshmen in college hear in physics 101.

The nature of the “two body problem”
The basic idea is that increased women in the scientific work force lead to couples in which both people are income earners.  Many women (and men) in physics marry people who also have careers; many are also academia, and some even in the same field. The problem lies in that both people have to find a career in the same place. Some universities have created funding to hire multiple professors at once for just this reason. But other than that, I haven’t heard of anything but a case by case basis – and definitely nothing for graduate students. Many times, it involves someone sacrificing their career (partially or wholly). This creates an especially difficult problem for those of us who are working on an experiment located half-way around the world.

Briefly about me
I – like all other students in my group – was expected to move to CERN while working on my PhD. My husband, Richard, works in the television industry in New York. Like me, he’s just starting out his career. Our solution was for me to move to France, with the start of the LHC, and him to stay in New York. I thought I would remain for the first year of running, then return to New York and finish my PhD there. Then, one thing lead to another and as it turned out, my year stay ended a few months before new start up is supposed to be. Instead of staying out here another year, I decided to return to New York. Why you ask? many reasons. Not to mention, we already spent a year apart. (Something that some colleagues seemed unmoved by).

What does this mean?
The next few years I’ll be between 2 places. Like most people starting out, I’ve had to try to find balance between work and a personal life. I guess the point is that I’ve found this balancing act tends to be particularly prevalent especially among women in science, and is something – I believe – isn’t talked about enough.

Next time, I’ll talk about the joys of attending meetings in my pajamas.

-Regina

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