“It’s OK to be driven by curiosity alone”

14 maj 2019

Karin Schönning investigates the magnetic moments of some of the smallest building blocks of matter: "The spin of hyperons is fairly easy to measure, so if you like spin, hyperons are a goldmine".

As a researcher in nuclear physics, Karin Schönning gets to explore what the Universe is made of. Last year, she received the Robert Thalén prize for her contributions to the particle physics experiments BES III in China and PANDA in Germany.

“If like me you assume that the Universe can be understood, you really want to understand it. And in that case, the residual strong force or strong interaction and the Universe’s missing antimatter belong to the biggest mysteries of all."

That she would become a nuclear physicist was not something that Karin Schönning could ever have imagined when she was a child, however. Instead, she wanted to be an archaeologist. This was helped along by 1980s educational TV programmes about archaeological digs.

“If you don’t come from an academic home, archaeologist is perhaps the first scientific profession you come into contact with. Taking this to its logical extreme, one could say that even particle physicists and nuclear physicists are a kind of archaeologist – only we don’t confine ourselves to looking at the history of mankind on Earth, but look at the history of matter in the Universe,” says Karin Schönning.

Karin grew up in the tiny village of Lingbo in Hälsingland province with parents who were very interested in the environment and were opponents of nuclear power. In the early years of high school, Karin Schönning wanted to learn more about nuclear power, which she associated with something evil. She came to revise her views, but what she discovered above all was her fascination with things so tiny that they are invisible to the naked eye.

“Having environmentally aware parents gave me the spark to learn more about energy and how to develop better sources of energy. But I didn’t go further down the applied track.”

While completing her Master programme in Engineering Physics in Uppsala, it instead became clear that her great passion lay in basic research. During her internship at CERN, the European laboratory for particle physics in Switzerland, she got to analyse signals from particles made up of strange quarks called kaons. Strange quarks are a heavier “sister” to the up quarks and down quarks which make up the protons and neutrons that we consist of, explains Karin Schönning. The strange quark is considered to be an elementary particle, but its life is only around 0.0000000001 – or ten to the power of minus ten (10-10) – seconds. A single quark cannot exist alone – only in combinations of three, or in quark-antiquark pairs. How these quark systems or hadrons are held together is a great mystery to researchers, as well as how this enormous force generates 99 per cent of all the visible mass in the Universe.

“To find out how these systems function, my research team and I study what are called hyperons. Hyperons are composite three-quark systems, just like protons and neutrons, but where lightweight quarks have been replaced by heavier quarks such as strange quarks or charm quarks,” says Karin Schönning.

“On the one hand, we look at what the internal structures of hyperons look like, such as how the quarks are distributed and their motion inside the hyperons, and on the other hand how hyperons decay. It’s particularly interesting to compare how hyperons decay with how antihyperons decay.

New particles continually arise due to particle collisions or decay as a result of interactions. Since there is a high probability that hyperons will decay into just two particles, according to Karin Schönning this makes them quite easy to study.

“You can measure the direction in which the products of the decay fly off and from this you can calculate the direction of spin of hyperons and antihyperons. It is interesting to know how they relate to each other and if the decay patterns of hyperons are different from those of antihyperons.”

Why is that?   

“Well, because we assume that matter and antimatter ought to function in the same way, but mirror-reversed. The problem is that we don’t really understand why our Universe consists of matter and not antimatter. Because equal amounts of matter and antimatter ought to have been formed in the Big Bang. How hyperons decay can provide clues to this.

It’s difficult to grasp the existence of something non-existing like antimatter, or for that matter how invisible quark systems constitute virtually everything in the environment that we live in. When Karin Schönning then describes how researchers can measure the magnetic moment or spin that goes on forever, it becomes quite mind-boggling. But the methods researchers use to figure out how these systems function are classic scientific methods. 

“When you have a system that you don’t understand, you make a small change such as replacing one of its components with something else and then observe how the system responds,” says Karin Schönning. How much of the mass will now consist of quarks? How much spin comes from the quarks if we tweak a little here? We can learn things from this.”

Today the structure of hyperons can only be studied at using the Beijing Spectrometer III (BES III) experimental facility in Beijing. Over 400 researchers from 14 countries are working there. Karin Schönning is the coordinator for one of the research teams working with software development and data quality for BES III. The work covers everything from analysis methods to quality assurance.

“In these big international research collaborations, there is a great focus on design and preparations in order to get experiments to work. In addition, in a short period of time we gather very large quantities of data with complex patterns, which is a huge challenge in terms of computation. Much of my job involves reading reports and drawing conclusions as to how we can do better analyses.   

Another experimental research collaboration is currently designing and building the PANDA detector, which will be a part of the Facility for Antiproton and Ion Research (FAIR). The latter is currently under construction at the GSI Helmholtzzentrum für Schwerionenforschung in Darmstadt in Germany. Karin Schönning and her colleagues at Uppsala University are involved in this collaboration, which researchers hope will lead to more revelations about how hyperons are formed from collisions between protons and antiprotons.

“Once FAIR is complete, in PANDA we will be able to collide protons with antiprotons and produce perhaps 100 times the number of particles per second as we can in today’s facilities. We will then be able to achieve even greater precision, which is essential to really draw any conclusions.

Omega-hyperons have historically played an important role in the understanding of the strong force and the existence of quarks: "With the PANDA-experiment in Germany, we’ll be able to study Omega-hyperons in detail and measure their spin polarisation, which we hope will lead to new knowledge leaps", says Karin Schönning.
 

“Previously, some experiments have had good precision, which others have had high intensity. But the next generation of experiments will combine high intensity with high precision. This opens the door for conducting a whole new flora of new types of experiments.”   

Karin Schönning biggest research success to date is the discovery that a lambda hyperon has a certain polarization or spin direction that it prefers. This is related to the lambda hyperon’s internal structure which in turn depends on the strong force or strong interaction.

“This is the first time we have been able to determine the complete time-like structure of any three-quark system.

Her next goal is to investigate the dependence of the polarization or spin on energy and if it is different for other hyperons. But this is more of a milestone than a goal.

“I do not foresee that the day will come when everything is said and done, and I can say, ‘Okay, right, what am I going to do now?’ These underlying questions are not something that will be answered in one day, or a year or so, but something I anticipate devoting the rest of my life as a researcher to.”

 

Anneli Björkman
7 May 2019

 

FACTS IN BRIEF KARIN SCHÖNNING

Age: 41

Title: Senior lecturer in particle physics, Uppsala University

Honours in brief: The Robert Thalén prize 2018 from the Royal Society of Sciences, Wallenberg Academy Fellow 2017 (in Swedish only)

Family: 11-year-old son and partner

In her spare time: I spend time with my son, sing in a choir and sing in a band of nuclear physicists including senior professor Tord Johansson, who plays guitar. We mostly perform at various physics events at the University.

Hidden talent: A memory for faces. And I can tiptoe in high heels!

Likes to read: Each evening and whenever I’m commuting or travelling. I particularly like Margaret Atwood, Moa Martinsson and Joyce Carol Oates, but I also read detective novels and scientific literature.

Would like to do more: Travel by train instead of plane. I have replaced many flights with train travel, but would like to do this more, and that’s something you need to have more time for. It’s a dilemma, especially when you work with China. But I think a lot about how we can streamline the work we do. For example, I’ve said to my colleagues that when they have to travel over to China and assist with data collection, that they should try to combine it with something else so that the trip can serve more than one purpose. And if you’re going to run a workshop in connection with a meeting, hold the workshop so close in time to the meeting that you don’t need to go home in between.

If I hadn’t become a researcher: I think there is some kind of committee that sits and decides on applications from people who want to change their last name to something special, and they get so many crazy ideas in the applications. I would like to sit on that committee! Haha! Once I saw a list of the names they had said No to – like Cottontail-Rabbit, for instance. It must be a really cool job.

About physics for students: In recent years, I’ve put a lot of thought into how teaching can be adapted to give students the knowledge that we use in my field. Most who do their degree project with us have not learned statistical methods for data analysis during their first-cycle courses, so they have to start from scratch. The students have knowledge in programming, but more emphasis could be placed on algorithms, in particular for filtering and analysing data, and those with a connection to physics. 

And then I would like students to realise that a physicist is neither a theorist with pen and paper nor a Balthazar with screwdrivers and soldering irons – that there are lots of ways of doing physics and that there is something to suit, if not all, then many.

 

Read more:

New method to study matter and antimatter (In Swedish only)

Research: New Particle World Record Key to the Mysteries of the Universe?

Protonen och dess syskon – en nyckel till materiens inre struktur (The proton and its siblings – a key to the inner structure of matter - in Swedish only)

More about Karin Schönning and research in nuclear physics at Uppsala University