The 2008 Nobel Prize in Physics was announced this week and it has gone to three theoretical particle physicists for their work on the Standard Model and ’symmetry’.

Critical to our understanding of the subatomic realm is the concept of symmetry. Physicists look for descriptions of nature that treat the various particles and forces in the same way. It makes a lot of sense actually. Think about a bunch of pool balls on a billiard table. The laws that describe how they scatter off each other is the same regardless of the balls’ colors or whether they are solid or striped. They all rebound off the rails in the same way regardless of which rail is hit. There is also a mirror symmetry to the pockets and a shot from the right side to the left corner pocket looks just like a shot from the left side to the right corner pocket, and so on.

Physicists expected that similar rules would apply at the subatomic level. That is, that processes would look exactly the same when viewed straight-on or in a mirror (spatial inversion) or if you replaced particles with their antiparticles (charge inversion).

In the moment of the Big Bang, matter and antimatter (electrons and positrons, quarks and antiquarks, etc.) would have been produced in identically equal amounts - initially things were symmetric. When matter and antimatter particles collide they annihilate into radiation and the matter disappears. Slowly, the identical amounts of matter and antimatter would have annihilated each other until all that was left was a Universe full of radiation. (Return to our billiards example. Imagine if stripes and solids destroyed each other when they collided. If the balls were all kept moving on the table, eventually, each solid would annihilate each stripe and the table would be empty.) A Universe void of matter particles would mean that protons, molecules, planets, stars, galaxies and life would have never had a chance to develop.

But the symmetry, it turns out, between matter and antimatter is (fortunately for us!) ever so slightly broken. The result is that over the course of time, the Universe that we live in has come to be dominated by matter instead of antimatter. The asymmetry exists at the level of one part in 10 billion (1 in 10,000,000,000!), but is has been just enough to tip the scale and allow matter to dominate in the end. Whew!

The theoretical development of this idea of symmetry breaking is what has earned Nambu, Kobayashi and Maskawa the Nobel Prize in Physics. Later, the effect was seen at particle accelerators in the US and Japan. Additionally, Kabayashi and Maskawa’s work predicted there would be a third generation of quarks (the bottom and top) two decades before the top quark was finally seen in a particle accelerator here at Fermilab.

For more information, see the Nobel web site where there is a concise summary of the ideas developed by the three laureates for the public.

Your next question may well be, “Okay, the asymmetry exists, and it is a really, really good thing for us, but WHY is there this asymmetry in the Universe?” Well, that is a great question and continues to be an active area of research in the field.

According to its website, Science Chicago is “an ambitious year-long celebration of scientific discovery and adventure that will captivate kids ages 9-90 with the amazing array of world-class resources available right here in Chicago.” As you will see on their site, the plan is ambitious indeed. For an entire year there are countless presentations, interactive exhibits, tours and learning opportunities of all kinds scheduled throughout the Chicago area. On Saturday, September 20, the year was kicked-off with LabFest, a free event at the Museum of Science and Industry (MSI) in Chicago. As part of the event, scientific and engineering institutions from the area set up tents on the front lawn of MSI with scientific displays catered to families and school groups. I was fortunate enough to join a group representing Fermilab.

Our tent was highlighted by Fermilab’s own “Mr. Freeze” who wowed the kids all day with his dewar of liquid nitrogen, levitating super-conducting train and frozen marshmallows.  We also had stations with an inclined plane and skateboards among other rolling objects demonstrating the importance of an object’s moment of inertia on how it rolls, a spiraling ball track that had kids running in circles all day, a spinning bicycle tire and lazy-susan amazing kids and adults alike with the transfer of angular momentum, deflating and infating ballons using ice and heat, as well as a wall of display posters showing some of the main experiments being done at Fermilab.

To my mind, the day was a huge success. I have no idea how many people came through the event, but it was easily in the thousands, and the Fermilab tent looked to be one of the most popular stops. I would encourage anyone in the Chicago area to check the Science Chicago schedule for events that interest them. There are activities catering to all scientific interests and age groups and they will be going on all year.

After writing about a first in the world of physics with the acceleration of protons at the LHC, here I share a personal first. This past Sunday, September 14, I ran my first half marathon with 10,375 other crazy people at the Banco Popular Chicago Half Marathon. Many believe that anyone who would run 13.1 miles by choice is a little nuts, but choosing to do it under the inland remnants of a hurricane is borderline certifiable.

Chicago recorded a new single day rainfall record when 6.8 inches of it fell on the city on Saturday. The rain continued to come down until late in the afternoon on Sunday, raining for nearly 48 straight hours over the weekend.  I captured the weather radar image to the right en route to the race about 6:00 am.  What you are seeing is the remnants of hurricane Ike which caused so much damage along the Texas coastline headed straight for the Great Lakes region.  After an encouraging break in the rain for about 30 minutes before the start, the yellow and orange region of the storm arrived at Chicago almost exactly at the start of the race at 7:30 and it proceeded to pour for the rest of the day! As miserable as that may sound, the rain wasn’t all bad. It was certainly effective at keeping the runners cool through the race and I ended up finishing several minutes quicker than I expected. Next month I will try my luck with my first full marathon at the Chicago Marathon on October 12. I’ll let you know. . .

The past week has been a uniquely exciting one within the world of particle physics.  It’s not everyday that the field makes headlines in newspapers around the globe, but that is exactly what happened when the Large Hadron Collider accelerated its first protons on Wednesday, September 10, 2008.

The turn-on of the LHC may seem an odd entry for a blog by a neutrino physicist, but the point that I wish to make is that it really is not at all.

The successful start-up of the LHC is an event to be celebrated by all of those interested in particle physics research. The planning and building of the LHC and its massive detectors goes back some 20 years, and Wednesday’s events mark the start of the gradual transition from planning and building into analysis and discovery.  It may well be several years before the data begin to reveal evidence of as-yet-unseen physics (or, even better, as-yet-unthought physics!), but the feeling of anticipation has risen this week for all who follow the field.  I joined about 400 hearty enthusiasts at Fermilab early Wednesday morning (things kicked off around 1:30 AM and breakfast was eventually served about 4:30 AM!) to follow the event live via the video satellite link between the LHC control room at CERN and the remote operations center here at Fermilab.  There were physicists, government representatives, and local families and high school students all in attendance.

An old friend from high school, after reading about it all over the news, emailed the next day to ask if I was “driving the particle collider in Europe last night”.  I’ve received several other notes this week from friends around the world and in a variety of fields asking about the LHC and how it relates to what I do.  It’s a very good question. . .

In November of last year a committee of about 20 physicists from around the US (known as the Particle Physics Project Prioritization Panel, or “P5″) was assembled and tasked to create a 10-year project road-map for the US high energy physics community. Their ~90 page report outlines a broad program to address the open questions in the field where input from three scientific “frontiers” would be necessary to inform our understanding of fundamental matter and the evolution of the Universe. These are the Energy Frontier, the Intensity Frontier and the Cosmic Frontier.  The Venn diagram to the left, taken from the report, summarizes their view very concisely. Put very very simply, I work in the green circle.

The LHC, of course, constitutes the Energy Frontier. The TeVatron accelerator at Fermilab has been colliding beams of protons and antiprotons at 1 TeV (TeV = Tera-electron-volts, or one trillion electron volts, or the amount of energy an electron gains in a 1 trillion volt battery!) for many years. The LHC will improve upon the TeVatron’s reach by a factor of 14 to 14 TeV. From Einstein’s most famous equation, E = mc^2, more energy means the ability to create more massive new particles. This additional energy, plus the ability to create many more proton-proton collisions per year at the LHC, are the reasons why the LHC will be able to see new forms of matter not seen at Fermilab. Famously, of course, they are hoping to create the Higgs Boson particle, believed to be the explanation for why matter has the property we know as mass in the first place. Whenever we have extended further out into the Energy Frontier in the past, we have discovered unexpected and exciting things. Hopefully, the LHC will follow suit in the coming years.

The Intensity Frontier is so called for the reason that to study certain extremely rare phenomena we must create incredibly intense beams of particles. Generating such intense beams can be every bit as technically challenging as creating a higher energy beam. As pointed out in my previous post, to study neutrinos one must have such an intense source.

Fermilab remains the world leader in generating intense neutrino beams with two active beams running at the laboratory. One of these, the NuMI beam line (Neutrinos at the Main Injector) directs the neutrinos at a detector almost 500 miles away in Minnesota! The MINOS detector is built deep underground in the Soudan iron mine near the Canadian border and sees neutrinos from this beam. It turns out that many of the neutrinos created at Fermilab change into another kind of neutrino before arriving at Soudan! - a phenomenon known as neutrino oscillations.

There are a variety of extremely rare particle processes, some dealing with neutrinos and some not, that, if detected, would be evidence of physics beyond our current models. The Intensity Frontier, therefore, is comprised of many different experiments looking for different extremely rare phenomena. I’m sure I will have opportunities in the future to explore some of these experiments and what they might be expecting to find in their data.

The Cosmic Frontier includes a wide array of experiments designed to study cosmic phenomena using telescopes, satellites, deep underground detectors, etc. Studying supernova explosions for what they can tell us about the evolution of the Universe, or solving the mysteries of dark matter and dark energy have become some of the most exciting goals in modern physics.

What the Venn diagram above is meant to convey is that the phenomena that might be discovered at the LHC can also be seen in high intensity experiments or cosmic particle experiments and vice versa. Detecting phenomena in multiple ways can provide an important means for breaking ambiguities and give physicists great confidence in their interpretation of the experimental results. Additionally, there are open scientific questions that can only be answered by continuing to explore on each of the three frontiers of particle physics.

Okay, so the basic goal of particle physics research is to understand matter at its most fundamental levels. We hope to know the properties of the matter particles themselves, why they are like that, and how matter interacts with other matter. From this basic understanding, we can explain everything from how electrons travel in a wire to create electricity to how nuclear fusion in the sun creates the energy so vital for life on Earth. The field began more than a century ago studying the electron and later the protons and neutrons that make up every atom. In the 1970’s it was discovered that the protons and neutrons actually have substructure comprised of quarks and gluons (the electron still looks to be fundamental). More than a century of building ever more sophisticated experiments and developing increasingly advanced models have resulted in what we call the Standard Model of Particle Physics.

The Standard Model is a list of known fundamental matter particles and their properties and a mathematical description of the interactions (or forces) that can occur between them. The diagram on the left summarizes the particles: six quarks (up,down,charm,strange,top,bottom), the electron (e) and its two heavier cousins (muon and tau), and three types of neutrino (denoted by the Greek letter n, or nu - looks like a ‘v’). That’s it! Everything we can see in the Universe appears to be made up of these 12 particles and their antimatter partners. (For those who know about dark matter, note I said everything we can see. We still don’t know what dark matter is, but we are searching hard!)

Neutrinos are the least understood of the fundamental particles. They are electrically neutral, have very little mass and interact only via the weakest of the known forces. It has only been in the last 10 years that we discovered that neutrinos have mass at all (we know the mass of an electron neutrino is less than 2 billionths that of a proton, but we still can’t say exactly how small it is). But there are so many neutrinos permeating the Universe that they may still make up a sizable fraction of its total mass. Neutrinos are a major player in the most important events occurring throughout the Universe (from the Big Bang to supernovae to the active centers of other galaxies) and therefore can tell us a lot about those events. The nuclear processes in the sun are giving off so many neutrinos that, even 90 million miles away, some 50 trillion of them are passing right through your body each second!

Despite the incredible number of neutrinos flying around, it took physicists 25 years from the time the neutrino was first postulated to exist to actually detect the neutrino experimentally. This is because of how incredibly weakly they interact with other matter. An average solar neutrino might pass through a light year of solid lead (that’s almost 6 trillion miles!) completely unaffected. An average proton might make it a foot!

Why in the world is that? As mentioned above, the Standard Model includes descriptions of the various forces through which matter particles can interact. Currently we know of four distinct forces. The most familiar of these is the gravitational force, the force of attraction between all objects in the Universe with mass (gravity at the quantum scale, actually, has not yet been successfully incorporated into the Standard Model framework, but this is a major effort in theoretical physics). The next most familiar is the electromagnetic force. Who is not familiar with the attractive force between two staticy socks, or the magnetic forces that overpower the gravitational ones in holding a child’s drawing to a metal refrigerator? Electromagnetism is also the force of chemistry. Different elements are held together by the electromagnetic forces between charged atoms. For all of these reasons these forces are quite familiar to everyone.

But there are two more forces that physics has uncovered in the last century. Both are nuclear forces, meaning their realm is the tiny tiny nucleus of atoms - something much less familiar in everyday life - but, otherwise not so different from the other forces. The strong nuclear force is what holds protons and neutrons so tightly inside the tiny nucleus. Did you ever wonder why many protons (remember like-charges should repel!) are able to be held so closely in a nucleus? The strong force is an attractive force for protons and is stronger than the repelling electromagnetic force, so it wins.

The fourth known force between matter particles is the weak nuclear force. The weak force is aptly named being about 11 orders of magnitude weaker (that is, 100,000,000,000 times weaker!) than the electromagnetic force and 13 orders weaker than the strong force. Of the twelve fundamental matter particles (six quarks, the electron and its two heavy cousins, and three types of neutrinos) the neutrinos are the only ones which interact only via this weak force. This means that to study neutrinos in the laboratory you need to have a source of trillions of them or take trillions of times longer to collect your data. Fortunately, experiments go with the first option or I might have been a graduate student even longer than I was!

So while you can’t see neutrinos or smell them or hear them, physicists have finally learned to detect them using enormous, sensitive detectors. By doing such experiments we can learn about the nature of the neutrino itself or about the distant cosmological source (the sun, a supernova, etc) that created them or both. Neutrinos indeed have much to tell us about the Universe we live in - they’re just a bit shy. This fact generates both the challenge and the reward of studying them.

. . . and welcome to my blog. This is my first posting and, as such, I’d like to use it to say a little about myself and to tell you why I’ve decided to enter the expanding world of the online diary in the first place. It seems blogs are everywhere these days. Google has a search tab dedicated to finding blogs and will uncover some on just about any subject you can imagine. I, personally, read several blogs maintained by close friends who are off on an adventure of some sort. I have enjoyed following their chronicles and have learned new, interesting things from their postings.

My intent is to share about my work as a neutrino physicist working at the Fermi National Accelerator Laboratory in Batavia, IL. The main content should, therefore, be about current research efforts in high energy particle physics. What are the open questions and research goals in the field? What experiments are being done to search for answers? My approach will be more anecdotal than technical and will hopefully give you a sense of what it is like to do this type of research. I’m sure there will be posts that don’t really touch on physics as well since, like anyone, I have a variety of interests beyond my work. But hopefully these will make for a more complete picture and provide a bit of context.

Many physicists’ stories begin with, “When I was a kid looking at the stars. . .” or “I’ve been taking things apart to see how they work since I was six. . .” Actually, when I was six I was putting things together - I wanted to be an architect.

I was born in St. Louis, Missouri, but my family moved to Topeka, Kansas when I was six (a year later the Kansas City Royals played the St. Louis Cardinals in the World Series - such conflicting times for a young baseball fan!). I grew up there and eventually attended the University of Kansas in Lawrence. Architecture turned out to be more than a fleeting desire, so I entered KU to study architecture and architectural engineering. It wasn’t until the end of my fourth year that I took a modern physics course and realized that I really wanted to be a scientist.

I got my first taste of experimental research that year, joining an experiment being performed in Antarctica which was searching for extremely high energy neutrinos being ejected from distant cosmological sources. I knew I was in the right field when it created the opportunity to travel to the Amundsen-Scott South Pole Station in December, 2000.

I attended graduate school at Columbia University and worked on another neutrino experiment, MiniBooNE, this time looking for evidence of neutrino oscillations - the idea that different kinds of neutrinos can change into each other and back again. I also worked on the HARP experiment at CERN, the European particle physics laboratory in Geneva, Switzerland, which studied the rates at which different short-lived forms of matter (pions and kaons) are produced when protons collide into various solid targets.

Since finishing my PhD I have worked at Fermilab as a Leon Lederman Fellow and continue to work on neutrino projects. Currently I am working on the MINERvA experiment which is designed to study neutrino-nucleon (proton/neutron) interactions with great precision compared to previous experiments. What we will learn at MINERvA will advance our understanding of the neutrino itself and greatly improve our ability to interpret results from a variety of other neutrino experiments. I am also interested in a new technique being explored for studying neutrinos which uses large tanks of liquid argon as in the MicroBooNE project. I promise I will have much more to say about both experiments in future postings.

I live in the north-side Chicago neighborhood of Lincoln Square. It’s a long commute, but I love the neighborhood and can’t bring myself to leave. I discovered it years ago when taking guitar lessons at the Old Town School of Folk Music, a major icon in the ‘hood.

Besides physics I enjoy reading, sailing (that’s me defying gravity at the top of the mast - scary!), playing recreational sports with my friends, and playing my guitar as long as no one is around to hear me. I also love to travel and try to never miss an opportunity to go hiking and camping in the mountains or sit on a warm beach somewhere. I can only hope I am fortunate enough to include a posting about that in the near future!

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