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Archive for December, 2009

Relax, the year is over!

Thursday, December 31st, 2009

The year is officially over in more than half the world as I write these words. As every year comes to an end, it’s time to celebrate and to put to practice many traditions. Among these traditions, there are two that I wanted to share with you.
The first one is the UW-Madison Holiday Physics Colloquium. Every Friday throughout the year, a guest speaker will give a colloquium on his or her field of research, but the very last Friday before the end of classes is usually reserved to the 3rd year grad students.
The students will put together an incredible collection of skits and spoof videos, combined with live performances. The usual topics are: Grad school is terribly hard, TAing stinks, I can’t find a good topic for my thesis, and so on. The faculty always participates in such videos and performances and we all have a good laugh. Pizza is available for the entire department, as well as plenty of beer (this is Wisconsin after all!)
Here’s a video I found on youtube of a past Holiday Colloquium. They are very good, but they even get better if you know the professors and students involved.

The second tradition was unknown to me: it’s a real Race Around the World! and it doesn’t even take 80 days, but a couple of hours. Apparently, every year this race is held in the South Pole Station in Antarctica. The participants have spent some time building all kinds of weird and funny-looking vehicles and crazy costumes to be in the 4 km-long race around the South Pole marker. It is certainly a well deserved celebration moment after all the hard work they’ve put working there while being away from their families.

There were a couple of serious runners that were going against the clock, too.

Here are some pictures that I took from an appendix to the latest IceCube weekly report. Enjoy! and Happy new year!

Picture 8Picture 9


Security Theater

Tuesday, December 29th, 2009

The attempted terror attack on a flight from Amsterdam to Detroit was basically the same flight I had taken less than two weeks prior on my way home from CERN.

Already my least favorite part of international collaboration was traveling by air. Somehow, I imagine my future flights to Genève are going to involve even more unpleasant security checks and rules.

There has been a lot said on the ridiculousness of many airline rules (xkcd: “A laptop battery contains roughly the stored energy of a hand grenade…”).

I have little to add, except to say that having spent a lot of time in aiports and on airlines myself, I agree that rules like prohibiting liquids adds little to our safety when flying.

Bruce Schneier summed it up nicely recently in Is aviation security mostly for show?:

Despite fearful rhetoric to the contrary, terrorism is not a transcendent threat. A terrorist attack cannot possibly destroy a country’s way of life; it’s only our reaction to that attack that can do that kind of damage. The more we undermine our own laws, the more we convert our buildings into fortresses, the more we reduce the freedoms and liberties at the foundation of our societies, the more we’re doing the terrorists’ job for them.

I hope airline companies and the TSA listen and someday make flying a more pleasant experience.


Who will pay for the arXiv?

Tuesday, December 29th, 2009

[Sorry if this is a little dry compared to my usual posts, but this is more of a news report for the HEP community.]

Last time I mentioned the INSPIRE system as an exciting development in high energy physics literature databases (no, that’s not an oxymoron). There’s another big change going on in that field next year, but this will be behind-the-scenes. None-the-less, it’s raised a lot of questions about the ownership and financial support of an important resource that is free to anyone in the world: the arXiv.

The e-print arXiv (pronounced “archive”) is a central repository of research articles in physics, mathematics, computer science, and quantitative biology. Since its inception in 1991 by theoretical physicist Paul Ginsparg, it has had a huge impact on the way science is done by providing free access to “pre-prints” of research papers. This meant that scientists from anywhere in the world with any background could access the latest research even if their university libraries didn’t have a copy of the particular journal in which it was published. This is a big deal since the cost of many of these journals created a gap between those institutions which could afford to pay for many journals and those which could not. In many ways arXiv “brought science into the 21st century” by allowing scientists to draw upon the collective scientific community more efficiently. Many credit it for pioneering the open access movement in scientific publishing.

But with increasing costs and the state of university budgets, the Cornell University Library (which operates the arXiv) is looking to find more cost-effective ways to support the arXiv and the much-needed overhauls in the software architecture (“arXiteXture”?). [Earlier this year Cornell closed its Physical Sciences library to help trim operational costs.]  Currently the Cornell library pays the $400,000/year operating cost to make the arXiv available free-of-charge to the rest of the world. Here’s the official statement so far:

Cornell University Library is beginning an effort to expand funding sources for arXiv to ensure its stability and continued development. We intend to establish a collaborative business model that will engage the institutions that benefit most from arXiv — academic institutions, research centers and government labs — by asking them for voluntary contributions. We are working with library and research center directors at the institutions that are the heaviest users of arXiv to refine our plan and to enlist support. We expect to release the plan, with a call for broader engagement and contribution, in early 2010.

There’s also a very handy FAQ on the funding changes, which are still a work-in-progress. Because the arXiv is such an important resource to a range of disciplines, the proposed changes have had some in the physics community asking whether it’s time to re-evaluate whether a single private library system should have ‘ownership’ of the arXiv as researchers contemplated the ‘nightmare scenario’ of the arXiv becoming a pay-to-use site. (Fortunately this is not the case.) Indeed, the arXiv has been instrumental in supporting research institutions that are unable to afford the costs of journals from for-profit publishers. The FAQ provides some insight about the direction that the arXiv managers are heading.

Currently the plan is to ask the “heaviest user institutions” (other university library systems) to voluntarily contribute to support arXiv operational costs. The FAQ states that the library has already secured commitments from 11 of the 20 institutions that make the most use of the arXiv. (I’ve seen an unofficial list; these include many of the ‘big name research institutes’ around the world.) In return, besides academic karma, these institutions will be recognized for their support with arXiv banners and would possibly be privy to more detailed arXiv usage statistics. The target appears to have such contributions support a fraction of the operating budget.  There is no plan to charge individuals for uploading or downloading papers from the arXiv. This business model is meant to be a temporary plan for the next three years while a longer-term solution can be figured out in collaboration with the wider community. It seems like the arXiv managers envision this long term plan being some kind of mixture of Cornell and user-institution support, but they are open to external support, e.g. from the National Science Foundation (which many physicists have suggested).

Just before the winter break the arXiv managers had meetings with the Cornell physics department to discuss the future changes to the arXiv. Unfortunately I was unable to attend that meeting because I was already back in California to spend the holidays with my family (… and to have transcontinental Skype conversations with my collaborators), but you can expect an official public announcement about the new arXiv program from the Cornell Library this coming January.



At Taipei, and Kyoto.

Sunday, December 27th, 2009

national taiwan normal universityLast week I have visited National Taiwan Normal University to give a talk at Taiwan string theory workshop 2010. This is in fact I guess 6th or 7th time visit to Taiwan, as I ama very frequent visitor to the Taiwan string theory group. Poeple there are always hertful, and this time again I enjoyed the visit very much, although the visit was only for three days.

Tanwan string theory group consists of members from many universities. Though some of the universities are very far away from the central Taipei (for example there are members in Shinchu city which is almot one-hour away from Taipei by a bus), people gather at National Taiwan University for enjoying seminars almost once every week. Discussions in every seminar is quite lively, and I am sure every visitor is surprised to see this kind of seminar series working in Taiwan. Most of post-doctoral fellows in Taiwan string theory group are Japanese, and so there is an intimate relationship to Japanese string theory community. Many Japanese researchers visit Taiwan, and I am one of them.

I visited Taiwan for the first time quite a long ago, probably about ten years ago. At that time the string group was not so big, but the basis of the present heartful group was already there, I enjoyed talking with active people there, all of them are my friends now. Since then, the group gradually expands and grows, with a national fund supported by the government, forming a string focus group. From the Japan side, thanks to prof. Inami’s effort for getting a special fund for visiting Taiwan, there are a lot of researchers, in particular young researchers, have visited Taiwan. Now, I think we can say that there is a strong connection between Taiwanese and Japanese string theory communities.

The workshop this time was joyful again, and I enjoyed talking with participants and other speakers, and also enjoyed drinking beers with my friends at a bar near the National Taiwan university canpus. I am happy to see my friends, in particular Japanese friends in Taiwan are enjoying their lives there.   

Kamo river near the Kyoto university campus.After coming back to Japan, I soon came to Kyoto for speaking about my favorite supergravity solutions and trials to solve some equations of motion for a holographic realization of color-flavor locking phase, at a Yukawa institute workshop on blackholes in higher dimensions. It was really a fun to communicate with people doing research on gravity and relativity, in particular at a drinking place. When I talk to them, I soon became aware of different motivations for computing the same background geometries. Well, that is obvious. and, even worse (or better), we have a confusing terminology. When I (and people doing string theory) say “backreaction”, the meaning is different from the “backreaction” which the gravity people use! — Quite confusing. But at least for me to know this difference is a benefit, for my presentations in the future. My talk was on 25th December, there is no Christmas or something in the field of gravity and relativity, it seems.

I wish you all a happy new year.


Well, someone ought to keep feeding the beast on the holiday, so I will do it.  Lots of people are taking a well-deserved rest this week, but the world of high-energy physics does keep motoring along.  CERN is closed down for the holiday, but the Fermilab Tevatron is running this evening and the experiments are taking data, quality of life be damned.  Many authors on this blog have written about the differences between American and European culture, and this qualifies as one more example; the Americans aren’t going to get something like a major world-wide holiday get in the way of taking data.  When I was a graduate student at Cornell, working at the CESR storage ring there, we’d always be running through the holiday too, and as a Christmas non-celebrator, it was always a personal point of pride for me to take a shift that day.  In fact, it was always the time when the machine would have its smoothest running and we’d acquire the most data, largely because no one else was there to muck around with things.

Anyhow, we are closing out a great year for the LHC.  The repair work required a tremendous amount of effort, and it paid off in the machine performance that we saw in November and December.  Last Friday, just before CERN closed, there were presentations from all of the experiments on what they have done with the data so far, and I thought they were all really impressive.  So many things are working out of the box — we are seeing the phenomena we ought to see at these low energies and collision rates, and everything is matching up very well with simulations.  (One could argue that after twenty years of planning, we’d better be this ready!)  There is nothing in the way of new physics here, as there isn’t nearly enough data or collision energy for that, but getting these fundamentals right means that we’ll have an easier time making discoveries when the conditions exist to do so.

So all I can say is that we’re going to have a great 2010 ahead of us.  The LHC will turn back on in mid-February, ready for higher-energy collisions, and we’ll be recording data through much of the year.  I’ll try to write something here on Christmas 2010, and I expect that there will be a lot of good news to summarize.



Thursday, December 24th, 2009

The last lecture and the last meetings for this year are done, and I’ve just returned the second iteration of the proofs for my STAR spin physics paper to the journal.

Snow next to teh Autobahn on the way to Frankfurt.

Snow next to the Autobahn on the way to Frankfurt.

Now Christmas is here, and it is time to “decelerate”. The year has been a wild ride: New Projects starting, significant progress in others, two diploma theses finished successfully in my group, another one started and now five PhD students in various stages of their research projects… After one year of getting started in 2008, this year my new group has picked up speed and is now buzzing more than ever with life and energy. For myself, it has been, among other things, a year of travel: More than 70 000 miles in airplanes, 20 multi-day trips, six of them intercontinental, and quite a few new places and impressions.

I am sure next year will be just as exciting, for me as well as for particle physics as a whole. Serious physics running will begin at the LHC, and answers to the question of where to go with the next big projects might start to emerge.

Before this happens though, now is the time to shift back a gear or two, and take a week to relax with friends and family, which is exactly what my wife and I will be doing. Despite the weather chaos that closed airports all throughout Europe, we were quite lucky not to hit any serious traffic or very bad road conditions on the way from Munich to the Frankfurt area, where we are both from. For quite a while, the Autobahn was leading us through a winter landscape, complete with falling snow and covered trees…

Now I’m ready for Christmas. Happy Holidays to all of you!


Looking forward to 2010!

Wednesday, December 23rd, 2009

As the sun is setting...

The end of the year...much more snow in real life!

2009 has been a spectacular year for me and for the world of physics! My time spent thus far at Fermilab has been amazing. I’ve gotten to become an “ACE” on the experiment CDF (Collider Detection at Fermilab), am putting the final push into a spectacular analysis that promises to be my thesis (a Search for Gauge Mediated Supersymmetry), have gotten to be at the U.S.’s beating heart of particle physics during the exciting start-up the LHC (Large Hadron Collider), and got engaged to a wonderful and supportive woman!! (Please note that these are not listed in any sort of order of importance…)

As I look forward to the upcoming year and wish all of my friends and colleagues in the field a Happy Holidays I become very excited at what results we will have in hand in the coming year.

For myself and my group at Texas A&M we have been hunting down the many challenges of doing a delayed photon search at CDF. With many many hours spent pouring over plots, code, bugs and results we are always moving closer to being able to go to full analysis and potentially end my time as a graduate student. This alone is enough to be excited about and I can’t wait to share our results (once we have them and get them blessed) with the rest of the physics world.

With the Tevatron humming along as good as ever delivering some of the highest quality particle physics data to be had we are sure to have lots of good events for our hunting. As recently posted on the Tevatron’s facebook (via Ron Moore, another quantum diary blogger)

Store 7444 colliding with initial luminosity = 306 ub^-1/s! Finally – first time over 300 since the summer shutdown!


The Tevatron delivered 51.3 pb^-1 to the experiments over the past week with 137.5 hrs of collisions.

With messages like these coming to my Facebook account I have a lot to be excited about right here at the Tevatron.

But even more so we saw some amazing things come out from the world of particle physics and dark matter detection in 2009 that make me look forward to 2010 even more.

Result recently presented by Lauren Hsu at Fermilab on behalf of CDMS showing tantilizing possibility of the detection of Dark Matter

Result recently presented by Lauren Hsu at Fermilab on behalf of CDMS showing tantilizing possibility of the detection of Dark Matter

As the image here shows the CDMS collaboration (of which Texas A&M is a member of) just showed their latest results for runs taken over the last year.

For those of you who don’t know CDMS is a direct dark matter detection experiment that uses really sensitive equipment deep in the bottom of a mine to shield itself from outside sources to search for dark matter interactions.

As Lauren Hsu put it at the Fermilab colloquium, they are at the “Low Background Frontier”. Their results showed two observed events with an estimated background of 0.8 events. Now this isn’t enough to call it finding anything…but it is tantalizing. And as my friend Homer said, “you could sneeze those other two events into the signal region…”

However you choose to look at their results it is enough to keep you on the edge of your seat for what is coming in 2010.

So as not to overstate the obvious, we also have the LHC coming online in 2009 and looking to ramp up their activity in 2010. With the world’s highest energy collisions soon to come quickly in the early months of next year we will quickly have all kinds of things to analyze and discuss.

So in closing I want to wish everyone a safe and happy holidays and and am looking forward to a very good new year! Cheers!

Maybe there are some new particles in ol' Santa's bag for all of us

Maybe there are some new particles in ol' Santa's bag for all of us


What’s the first thing you do? Find the Higgs? Well, actually, you measure charged hadron spectra (see the first paper with LHC collision data from ALICE). It’s something all the LHC experiments are doing, so In case you were wondering why (or what), thought I’d try to explain. And for some reason, only after writing all this did I see Zoe’s nice post on the ALICE analysis. D’oh. Well, there are not many LHC results to talk about… yet…

On the multi-purpose experiments like ATLAS and CMS, these measurements are made by what is usually called the “Minimum Bias” group (maybe on ALICE and LHCb too, I’m not sure). The “minimum bias” part relates to how these collisions end up being recorded: by firing a “minimum bias” trigger. Some triggers are highly biased and only record collisions where a muon was produced, for example. A minimum bias trigger only requires that something happened: that was a collision. It gets a bit more complicated, because there are also “diffractive” collisions, but this post is already going to be long enough! Normally the rate of collisions is too high to record them all, so only a (random) small fraction are actually recorded. But for the first LHC runs, the rate was low enough that as many as possible were kept. This is one of the nice thing about minimum bias (and why it was the first paper): you don’t have to run for very long to get a lot of events!

Then the measurements themselves, which are things like dN/deta and dN/dpT. So, the proton is a ball of stuff: mostly quarks and gluons. When you smash two of these together, it is really the quarks and gluons that interact. Most of the time, the interactions are fairly “soft” (low energy), and the results is a spray of particles from the remains of the two protons. A seasonal analogy: take a snowball and throw it at a wall, you’ll get a satisfying thud and bits of snowball fly everywhere. Now, if you have a friend who is also willing to take part in this experiment, try throwing two snowballs so they hit head on in the air. This is pretty much like these “soft” proton interactions: bits of snowball flying everywhere. The aim here is to measure the debris of the protons in these collisions, and quantifying it by looking at, for example, dN/deta. The N here is the number of charged particles produced in the debris; eta is an angle with eta=0 is perpendicular (transverse) to the beam direction. So, it’s a measurement of the average number of particles produced at different angles from the beam. Similarly, dN/dpT is the average number of particles produced with different momenta in the direction transverse to the beam.

Now, why is this interesting? Well, depends who you ask, but here is my bias: occasionally, a quark or gluon will be carrying a large fraction of the proton momentum, and a “hard” (high energy) interaction will take place: a Z might be produced, or (we hope) the Higgs or some new particle. This is where the snowball analogy breaks down: it’s like throwing two snowballs, and a tiger being produced when they collide (see Figure 1). Quantum mechanics is strange…

Figure 1: What happens when you stretch an analogy too far

Figure 1: What happens when you stretch an analogy too far

Anyway, even when there is a hard interaction which produces the Higgs, there will still be some debris from the remains of the protons. And as the LHC reaches high beam intensity, there will probably be a couple (or more) of soft interactions between different protons at the same time. In other words, a lot of this debris flying around. We need to understand it, because when all this stuff hits the detector it might make it harder to find the Higgs signal.

And the problem is that this kind of soft interaction is very hard to calculate. We have some excellent models, but they have been tuned to the measurements made in the past. And different models tend to diverge when extrapolated up to the energies we will see in the LHC soon. So we really don’t know exactly what the debris will look like, and repeating these minimum bias measurements is essential. And how do you know you are measuring this correctly? Well, compare to previous measurements and see if you get the same answer. So, it’s very convenient that the LHC has so far run at 450 GeV per beam (earlier CERN experiments like UA1 and UA5 measured minimum bias at this energy) and 2.3 TeV (very close to the Tevatron energy, where CDF measured minimum bias).


Christmas Upside Down

Wednesday, December 23rd, 2009

The view from the balcony where I have my coffee.

The view from the balcony where I have my coffee.

While everybody else is reporting on the possibility of white Christmas, I am actually sitting in shorts and T-shirt while typing this blog entry. Today we have 33 degrees plus and in two days I will be on the beach. A few days ago I travelled with my husband from Hamburg through Paris and Rio de Janeiro to Porto Alegre in the south of Brasil. My husbands family is living here and we are going to spend Christmas and New Years with them. And afterwards we will stay a bit longer as this is actually my summer vacation. With a family in the souther hemisphere it is not the first time we go on summer vacation during the European winter, but it is the first time over Christmas. And this is really strange!
Porto Alegre is the capital of the southernmost Brazilian state Rio Grande do Sul and one of the biggest cities in Brazil. The city was founded in 1742 by immigrants from Portugal. In the late 19th century the city received many immigrants from other parts of the world, particularly Germany, Italy, and Poland. The vast majority of the population is of European descent. Therefore the city is a very interesting mix of Southern American and European charme. Most people who have not been to Brazil think only of Carneval, the Amazon or beaches. Or people ask me if I was robbed already. Of course this are very limited pictures of such a huge country and I only can speak for the South of Brazil.
Here in the South, Brazil is a very prosperous modern country with a good economy. Porto Alegre is the city with the highest living standard in South America and this is visible all over the place. I love to be here as the Brazilians are the friendliest people I ever met. They always want to make sure that everything is perfect for us and that we spend a very nice holiday. And not only the family members are caring, but just everybody we meet. When we ask for help (for example to find the way) the people are very eager to help. And if we do not understand, as our Portuguese is limited, they take our hands and show us the way.
Now is the first Christmas we spend here in Brazil. For us it is of course very unusual to think of Christmas and Santa Claus in the middle of the summer. The Christmas decoration is usually very green and the use of artificial snow is not common. As they don’t have that many fir trees here, the typical Christmas tree is a pine tree, or a lot of people have artificial Christmas trees, as the fresh trees don’t stay fresh in this heat. These are my very first impressions of Christmas in Brazil upside down and I think I have to report later on again.
A typical street in Porto Alegre, Brazil.

A typical street in Porto Alegre, Brazil.


While this won’t catch the as much press as the LHC’s upcoming steps towards a physics run, but there are big changes coming up in 2010 to the way high energy physics literature is organized. This is very important: the vast databases of physics literature available at our finger tips through the Internet are what separate us from the cavemen. (Er… something like that.)



Speaking of cavemen, those familiar with the history of the web at CERN will not be surprised to find out that the first webpage hosted in North America was a particle physics literature database, SPIRES, operated by the SLAC National Laboratory. The database allows anyone in the world to look up bibliographic data about a range of documents including items that aren’t journal-submitted papers: PhD theses, conference talks, technical notes, and even video recordings.

CERN has its own library management system, Invenio, whose killer application is the fantastic CERN document server. The CDS has a broad collection of materials, including a nice set of general audience videos that readers of this blog might like. The two systems have their own strengths: SPIRES is known for its ability to work with metadata while Invenio’s architecture is known for its scalability and performance. So, after a survey of high energy physicists, it’s no surprise that SLAC and CERN (along with Fermilab and the German HEP lab DESY) combined their resources to implement SPIRES “user-level functionalities” within the Invenio framework.

Screen shot 2009-12-22 at 8.55.11 PM

The resulting combined project was christened INSPIRE and the plan is to have a user release sometime next year. INSPIRE aims to produce a unified, modern HEP database that’s not based only on papers (and more recently recorded talks), but more generally information. This includes computer code, data, and figures. Instead of just searching, it also aims to tap into the potential of the Web 2.0 by implementing a rating system, following individual users, and even tracking data usage.

[Now for some shameless self promotion: these are all functions that I wrote about two years ago, likening them to link aggregation sites like Digg, e-commerce a la Amazon, and the grand-daddy of Web 2.0: Google itself.]

You can read more about INSPIRE through at the CERN Courier, interactions.org, Symmetry Breaking, a talk to the DOE High Energy Physics Advisory Panel,  and through some talks at the HEP Information Resource Summit. At that last link check out Travis Brooks’ demonstration of INSPIRE, or better yet, try out the alpha version yourself.