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CHIPP prize 2013

The secrets of ultracold neutrons

On the occasion of its 2013 meeting in Sursee (LU), the Swiss Institute for Particle Physics (CHIPP) has awarded the annual prize for outstanding research in the area of particle physics. Martin Fertl (29) received the prize for his research on the influence of electric fields on neutrons, conducted at the Paul Scherrer Institut (PSI) in Villigen (AG).

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From the 24 to 26 June 2013, Sursee was the epicentre of Swiss particle physics. The members of CHIPP, the organisation of particle physicists active in Switzerland, gathered for their traditional yearly meeting. They exchanged the newest research results and talked about the perspectives in their own discipline – this year for instance about the European strategy for particle physics, which fixes the future main axes of research in this scientific area.

Magnetometer enhancement

A highlight of the annual meeting is always the award of the CHIPP prize to a young researcher. This year, the 29 years-old Martin Fertl received the 3000 francs prize for his doctoral thesis. The thesis contributes to the nEDM experiment, one of the key experiments at PSI with around 50 researchers from six European countries (Belgium, France, Germany, Poland, Russia, Switzerland). The experiment performs searches for the 'electrical dipole moment' of the neutron, i.e. it probes if the spin ('angular momentum') of a neutron is influenced by an external electric field (i.e. if it interacts with the electric field). The nEDM experiment takes place in a cylinder of diameter 50 cm and height 12 cm; inside, the so-called 'ultracold' neutrons have a kinetic energy corresponding to a temperature of just 3 milli-Kelvin, only slightly above the absolute zero.

nEDM is a precision experiment, and Martin Fertl's knowledge helped to make it even more precise. The experiment makes use of a magnetometer based on quicksilver atoms, which allows the scientists to measure the existing magnetic field. Thanks to Martin Fertl's research, the sensitivity of the magnetometer could be largely improved, namely by a factor of 6. In addition, his knowledge lead to a betted control of systematic effects in the magnetometer.

Looking for antimatter

„Industrial applications of my work are not to be expected for now“, Fertl says, „but maybe a contribution to new scientific knowledge.“ The young researcher's work improves the conditions to make the nEDM experiment a scientific success. If the neutron's spin turns out to interact with electric fields, i.e. if an electrical dipole moment exists, then it will be a new hint towards an answer to a question that has bothered physicists for so long, namely why more matter than antimatter is being observed in the universe (although equivalent amounts of matter and antimatter should be created just after the big bang).

Martin Fertl is originally from Dachau (D) and has studied at the Technical University (TU) in Munich, as well as in Australia and France. In the last few years he worked as a researcher at PSI and wrote his Ph.D. thesis (supervised by ETH professor Klaus Kirch). What was for Fertl the big challenge in the writing of his thesis? „I had to familiarise myself with new fields such as optics and atomic physics, which were not the main fields of my diploma thesis “, says the researcher. Many practical problems also arose during the building phase of the experiment, as the following example shows: in order to stabilise the frequency of the laser required for spectroscopy, one employs quicksilver atoms that are embedded in a cylindrical cell made of quartz. The quartz cylinders used at first turned out to be inappropriate, since they would lose their transparency after only a few hours and become useless for optical analyses. Fertl had no other choice but to design by himself suitable quartz cylinders.

“The prize is a great recognition of my personal work, but also a distinction for my colleagues, which have contributed in many ways to the success of the experiment“, says the CHIPP prize 2013 laureate about the meaning of the prize. After the end of his activity at PSI, Martin Fertl would like to keep doing research abroad, in the USA or in Great Britain.

Benedikt Vogel (published 26. 6. 2013)


  • Elementary particles
  • Particle Physics