Showcase session

Where has all the Antimatter gone? Swansea University and the ALPHA Experiment at CERN

Austin: 31st October

Niels Madsen

Professor Niels Madsen is an experimental physicist who specializes in work on fundamental physics with antimatter.

His research interests include antihydrogen, atomic physics, laser cooling, plasma physics, fundamental physics, spectroscopy and non-neutral plasmas.

He played a significant role in the ATHENA team that first formed low energy antihydrogen in 2002 and is co-founder and group leader in the ALPHA collaboration that was the first group to trap antihydrogen and observe the first quantum transitions in it.

Professor Madsen has a research group at CERN which plays a leading role in the ALPHA experiment in both physics and hardware and software design, and led the effort to implement key techniques which resulted in the first antihydrogen trapping.

He was awarded a Royal Society Senior Leverhulme Fellowship in 2010 and in 2011 received the James Dawson award for Excellence in Plasma Physics Research.



The ALPHA collaboration works at the Antiproton Decelerator at CERN in Geneva, Switzerland.

The experiment is a collaboration between a number of institutions which aims to trap antihydrogen, with eye towards doing spectroscopy on this trapped antihydrogen atoms for precision comparison with hydrogen.

This comparison is motivated by the observation that the universe, counter to what one should expect from current understanding, consists only of matter. According to fundamental theories the universe should have been symmetric in the sense that it should consist of equal amounts of antimatter and matter.

One possible explanation for the discrepancy is that there is a small (and unexpected) difference between matter and antimatter.

Swansea's contribution to the ALPHA project:

  • Antihydrogen formation: Swansea has, as a former partner in the ATHENA experiment (also at CERN), extensive experience in forming antihydrogen by merging plasmas of antiprotons and positrons.
  • Plasma measurement and control: Swansea works in collaboration with Prof. Fajan's group from Berkeley on plasma measurement and control techniques for better control of the formed anithydrogen.
  • Superconducting Magnet Design and Control: Swansea has, in collaboration with colleagues at Berkeley and Aarhus, designed the superconducting magnetic trap for ALPHA and implemented a quench protection and magnet control system based of a set of FPGAs (Field Programmable Gate Array).
  • Positron accumulation and transfer: Swansea is a world leader in positron physics, and is the provider of positrons in the ALPHA experiment. Swansea has constructed, installed and is operating a positron accumulator in the ALPHA experiment. 

Matter vs Antimatter