Neutrinos, Theory, and Women in Physics

Dr. Yasaman Farzan is an Iranian neutrino physicist who obtained her PhD in 2004 from SISSA, worked in the theory group at the Stanford Linear Accelerator Center, is a Simons Foundation associate at ICTP, and is the first woman to be appointed as the Head of Physics at the IPM institute in Tehran.

Dr. Farzan talked to us about her neutrino research and being a female physicist in Iran.

Do you come from a academic background?

My father was a university professor in civil engineering. Being his daughter, I became interested in science. In high school, we had a wonderful geometry teacher, as well as a wonderful physics teacher. And through them, I got interested in physics in particular. In high school, I liked geometry, and mathematics in general. I participated in the Physics Olympiad competition, and I was on the Iranian team for the 1994 international competition in Beijing. 

I went to Sharif University to study physics. I did my master's thesis on particle physics there, and then my husband got a postdoc position at ICTP. I accompanied him to Trieste, participated in the entrance exam at SISSA and began my PhD there.

How do you think moving during your studies affected your career?

I think it affected me positively because I had the chance to experience the European academic atmosphere. My supervisor was Professor Alexei Smirnov at ICTP, and through him, I got a taste of the Russian approach. I'm very grateful for that opportunity. In the middle of my PhD, my husband was offered a postdoc at Stanford. We negotiated with them, and I went with him. I did part of my PhD at the Stanford Linear Accelerator Center (SLAC), in the theory division, under the supervision of Professor Michael Peskin, so I learned about the American style of physics research too. It is unusual to move from one place to another in the middle of your PhD, but I think in the long run, it was a positive thing.

What’s the focus of your research?

I'm working on the properties of a particle called a neutrino. This is an elementary particle, meaning that it cannot be decomposed to smaller particles, just like the electron, although electrons have an electric charge, and so they interact electromagnetically. Neutrinos do not have an electric charge, which means that their detection is very, very difficult, even though they're all around us.

“The Sun produces a tremendous amount of neutrinos, continuously. Billions of neutrinos pass through every centimeter squared of our body every second, but during our lifetime, at most one interaction will take place in our body.” 

Also, there are neutrinos remaining from the Big Bang; we call them relic neutrinos. Since their energies are lower, their detection is even more difficult. These are all around us, but since they interact only weakly with matter, our understanding and knowledge of them is limited. This makes them even more interesting for a researcher, as when we don't know something it is tantalizing to learn more about it.

I’m working on the possibility of having some invisible background that affects neutrinos on their way to the Earth, and how this can be tested and distinguished from other effects that have already been studied. The idea is to give some guidelines to experimentalists. 

I have a brilliant MSc student who thought of creating a model for explaining matter-antimatter asymmetry. Our world is composed of matter: protons, electrons, but we don't see many antiprotons and positrons - antiparticles - around us. This is a puzzle. We can make antiprotons, positrons in labs. This is an open question, and several models and explanations have been proposed. Now, we are imposing some new physics on one of the models, and we think that our preliminary results show we can help provide an explanation.

In another project, we are also speculating whether neutrinos have some interaction beyond what is known, and considering the consequences of this.

How are neutrinos studied?

The main experiments on neutrino physics are scattered around the world. There are quite a few experiments in Japan, like Super-Kamiokande, which are located deep underground to reduce the background radiation for detection. Neutrino experiments are mostly located in abandoned mines and in some cases, for example, the Sudbury Neutrino Observatory in Canada, even in a working mine. A tremendous amount of work is required there to reduce the background radiation.

There are also some smaller detectors, for example, deep in the Mediterranean Sea. One very important detector is the IceCube Neutrino Observatory in the South Pole, which uses the ice as a detector. Occasionally, a neutrino interacts with nucleons in the ice and charged particles are produced. These charged particles travel with a velocity larger than the velocity of light inside the ice, and emit Cherenkov radiation, which is just bluish, beautiful visible light. The detectors that are instrumented inside the ice can detect this blue light. Of course, there is an issue of background radiation reduction because cosmic rays can produce the same effect.

As a theoretical neutrino physicist, how much contact do you have with experimental groups? 

We build models and predict some observations for detectors. Experimental groups publish their results, and we keep ourselves updated on the bounds they have found. When we make a model, we aim to make sure that all these bounds are satisfied, and then we should have some prediction that can be tested. We keep in contact with colleagues in experimental groups, and ask them to also check the effects we are predicting.

I am now in the Deep Underground Neutrino Experiment (DUNE) collaboration, which involves a state-of-the-art neutrino experiment, which will be located in Fermilab, USA, with the detector 1300 kilometers away in another state, and underground. 

How has the Simons Foundation Associate grant affected your career?

Having contact with colleagues from all around the world is really crucial for us. Some say that for mathematicians and theorists, going abroad and talking with people is our lab.

 “ICTP and the Simon's Associates programme have helped me to come to Europe every year, interact with colleagues here, and also travel within Europe, because ICTP supports my visa and the visas of my students.”

We come here to Italy, and then traveling inside Europe is much less expensive. Usually hosts in other institutes in Europe support our travelling within Europe but not from Iran, which is more expensive. This helps me not only to have contact with colleagues here but also all over Europe. Sponsoring the visas is a big thing, especially for people from Iran. I am tremendously grateful.

What is your experience of being a female physicist in Iran?

Being female may even be an advantage if you are going to approve of what your seniors say. But when you start to have your own opinions, you sometimes criticize seniors or want to surpass them, and regardless of whether you are man or woman, you will be frowned upon. And if you are a woman, you may be disliked even more. So, this was a challenge for me. 

 “Fortunately, or unfortunately, I have lots of opinions and no trouble expressing them.”

The fact that my husband and I worked together in some cases made things more complicated because, again, fortunately, or unfortunately, our opinions are very similar. We were regarded not as a single person but as a team, and then attracted more hostility in some cases. But on the other hand, I have never been exposed to sexual harassment, because my husband was always close. Of course, although I have not suffered in this respect, I know that suffering exists. 

One of the conditions that I set when I became Head of Department at IPM in Tehran was that I would have full control over issues regarding sexual harassment. So far, we have not had any problems, and I have said to the students there that if they feel slightly embarrassed because of this type of thing, not to wait until it gets worse, but to come and talk to me. Fortunately, this has not happened, but we monitor this.

You set up a daycare at IPM. How did this happen?

When I became Head of Department, two of our three administrators required maternity leave, which I approved. Towards the end of their leave, they asked for space on campus to use as a daycare for their children. They were very shy about it because they knew that female scientists had previously asked for this and the answer was always “No.” 

I remembered that a senior colleague of mine, Professor Lindner at the Max Planck Institute in Heidelberg, felt that of all his achievements, the greatest was actually the daycare center that he founded at his institute. I wanted to do some something similar, but we didn't have a budget for it. I asked them to find a place where we could be sure that neighbors would not be annoyed, which they did. They found a nanny, insulated the space, and the children are very happy there. This allowed them to return to work.

How do your students differ from the time when you were studying?

Students in Iran are far more open to the world now than when we were students. Back then, there was no internet. We had a splendid scientific education, but when it came to social matters, people were kept very, very isolated and with more closed minds. Now, thanks to the internet, students know far more about the world around them. This new generation is curious; they are well educated and profound.