A rainy morning of July, we visit the Budker Institute of Nuclear Physics in Novosibirsk Akademgorodok with Galina Lazareva. Galina knows this place like home — her father, a nuclear physicist, worked here, and today she is a collaborator of the Institute herself.
Iron scraps and particle physics
Our guide through the Institute is a young scientist, working in the physics of elementary particles, one of the themes intensively studied in the Institute. He starts his presentation at the first exhibit of the Institute museum — the so-called VEP-1, one of the first particle colliders in the world, built in 1963. The collider looks like a 3 meter high metal cassette put on the side — it has two holes, one over another, on which different elementary particles would accelerate, and then collide in the place where two holes touch. This collider is not in use anymore but it stays an important memory for particle physics — the first scattering experiments were conducted on it, moreover, it is the only collider in the world where the particles would meet in the vertical plane.
All the colliders are based on two ideas. First, in order to study any small object, one needs a « physical microscope » with a wavelength smaller than that of the object itself. The objects of interest are, for example, kernels of atoms — having the size of 10-12 cm, in the best of cases. In order to study such an object with a beam of accelerated particles, one needs the wavelength of the particle to be smaller than the size of the studied object. The wavelength being inversely proportional to the impulse, the velocity is obligatory very high — hence, a collider is necessarily an accelerator. The second idea is to design the acceleration not in a straight line but in a circle. Indeed, when the particle accelerates in a straight line and then smashes at some plate, new particles are born, many reactions occur and may be studied — first particle accelerators were linear and sufficient for some basic observations. But, in a linear accelerator, the initial momentum — and hence the initial energy — is spent not only on the reaction but on the momentum of the particles born out of the reaction. The idea of a circular collider is that the global momentum of particles in the beginning is zero since they are launched in different directions — hence, all of the initial energy goes into the reaction itself.
Our guide leads us from one room to another, and the colliders mesmerize by their own complexity but, maybe even more, the complexity of the world that they are designed to unravel. And also… their growing sizes.
Two electron-positron colliders are in use today in Budker Institute. Both of them consist of two stadiums on which the particles accelerate — the first, preliminary stadium where particles reach high enough energies, and the second bigger stadium, where not only accelerations but also collisions happen, inside extremely complex elementary particles detectors placed at one (or two) specific points of the big stadium. The job of our guide, as well as many scientists working on colliders, is to construct experiments and analyze data on collisions, births and deaths of particles coming from these detectors.
The first collider is called VEPP-2000, and is of 25 meters in perimeter, built in 2009 (the number 2000 is not a date of construction but the possible energy of colliding particles). The second one is a VEPP-4, and is 300 meters in perimeter (and has to be walked around), with possible beam energies now going till 6 GeV. It was built in 1979 and modernized, in order to higher up the precision in the nineties. Several buildings in the Institute host these two colliders — in order to make the collider live and function, conduct experiments on it and treat the data, several dozens of scientists and engineers are employed in the Institute.
The building blocks of the colliders are gigantic magnets that turn the particles in order for them to go in circles. “It is Summer, and our two colliders do not work. Cooling off the magnets is too expensive. That’s why we can conduct excursions — there is no radiation here, rest assured!”, smiles our guide.
Budker Institute specializes in the production of magnets for colliders, and our guide says with pride that the Large Hadron Collider in CERN (as well as any collider in the world) uses Novosibirsk magnets. As of today, there are only seven working colliders in the world, two of them in Novosibirsk. Galina gets out from the excursion inspired. “I was brought up in middle of all these iron scraps — I though that they exist everywhere! Today I learned with surprise that it is not the case,” she says.
The hairdresser would do it better
Recently Galina has recently started a collaboration inside the Budker Institute — she works with a team of plasma physicists, designing computer models of the experiments conducted in the Institute. Plasma physics is another theme intensively studied in the Institute, a so-called low-energy physics, very different from the elementary particle physics where high energies are at stake. But she encounters same faces, Galina says. “I could show you my coauthors but what for? They look exactly the same as our guide — young and plump beardy physicists! But when they speak about their science, their eyes are shining.”
Galina spends most of her time modeling processes that are done in experimental installations.
Of course, it is hard to learn a new subject. In the beginning, my collaborators would say — you do not understand, everything is not like this! But little by little, they started to trust me. Now they say yes to whatever I propose — they see that the results come out from my ideas. We have very different approaches: in my models, the mistake of calculation is up to 2 percent. But in their real-life measurements, it is up to 50 percent. If you show it to a pure mathematician, he will go into a coma!
My collaborators are the most talented young theoretical physicists here. Of course, they can do these models themselves. But I do it better because it is my profession. You probably can do a haircut to your husband, but the hairdresser would do it better! The same for me here.”
I am afraid of babaykas, not physics!
Galina Lazareva is an applied mathematician, working with numerical models — mostly, she is designing programs and packages for specific experiments in various areas of science, from physics to biology, and situates herself somewhere in between physics and mathematics, and can see the interest of both approaches, and the reciprocal critiques.
The critique that physicists have to mathematicians is that they are not interested in what is really needed by physicists, that mathematicians are not goal-oriented. If you happen to be goal-oriented, physicists will be very happy to work together with you!
My collaborators from physics also need me to work fast, since the experiment only lasts one or two years, and then the physics moves over. This also is very different from research in pure mathematics. But I try to follow the rhythm — I decided that I want to do something useful, something related to the real life, with my mathematics.”
Trained as a mathematician, Galina formulates her goal as to state a mathematical model which is smart, well formulated and closed.
Once this is done, one can work with it, for the experiment but not only — usually, once the experiment is over, I continue thinking and working on the mathematical model that I have constructed, for many more years ahead,” she says. “In general, the goal of a mathematician-developer, working on an experiment,- is to help find meaning in the results of the experiment. Today it is a very rare luck to be able to design an experiment, the result of which will give directly an answer to the question that interests the scientists. Almost always one relies on a quite precise quantitative calculation that would be compared with experimental data. A mathematician adds different features of the physical system into numerical computations and observes if it gives an explanation of experimental data. If the two data (experimental and numerical) coincide well enough then the experimentators are convinced — ok, that’s how the process goes.”
When asked what she is afraid of, Galina tells about babays (or babaykas), night spirits that come from the dark when you are in bed, and take you away if you try to get out of it. Babays are usually not described because they seem scarier for children who do not know how they look. Although, Galina says, she is not at all afraid of physics — she likes to read new articles and change from one subject to another, completely new to her.
Pictures of the colliders were taken by Olga Paris-Romaskevich