Magnetic trapping will help unlock the secrets of anti-matter

November 18, 2010

A clearer understanding of the Universe, its origins and maybe even its destiny is a significant step closer, thanks to new research.

As part of a major international experiment called ALPHA*, based at CERN in Switzerland, researchers have helped to achieve trapping and holding atoms of 'anti-hydrogen', which has not previously been possible.

The project involves physicists at Swansea University led by Professor Mike Charlton, Dr Niels Madsen and Dr Dirk Peter van der Werf and the University of Liverpool under Professor Paul Nolan, all supported by the Engineering and Physical Sciences Research Council (EPSRC).

This breakthrough will make it possible to study 'anti-matter' closely for the first time, and so develop unprecedented insight into its composition/structure and improve understanding of the fundamental physical principles that underpin the Universe and the way it works.

For nearly a decade, scientists have been able to undertake the controlled production of anti-hydrogen atoms in the laboratory - a breakthrough which Swansea University also contributed to, with EPSRC support**. But as anti-matter particles are instantly annihilated when they come into contact with matter, it has not, until now, been feasible to study anti-hydrogen atoms in any detail.

ALPHA has therefore developed techniques that not only cool and slow down the anti-particles that make up anti-hydrogen and gently mix them to produce anti-hydrogen atoms, but also trap some of the anti-atoms for long enough so they can be studied.

The key focus of this effort has been the development of electromagnetic traps that have a number of cold species inside. These traps don't just provide the conditions needed to cool the anti-particles prior to mixing. The cold anti-atoms formed also have a tiny 'magnetic moment'*** which means they respond to magnetic fields. By arranging the magnet coils in the right way, it is possible to set up a magnetic 'well' in the centre of the anti-particle mixing zone where anti-hydrogen has been trapped.

"Every type of particle has its anti-matter equivalent which is its mirror image in terms of having, for instance, the opposite electrical charge" says Professor Charlton. "Because hydrogen is the simplest of all atoms, anti-hydrogen is the easiest type of anti-matter to produce in the laboratory. By studying it for the first time, we will be able to understand its properties and establish whether it really is the exact mirror image of hydrogen.

"That understanding will hopefully enable us to shed light on exactly why almost everything in the known Universe consists of matter, rather than anti-matter, and what the implications are in terms of the fundamental way that the Universe functions."

In order to detect the anti-hydrogen atoms they were released from the trap. The silicon detector used to determine the positions of the resulting annihilations was developed and built at Liverpool. Professor Nolan comments that "the unique clean room and workshop facilities in Liverpool, together with detector and electronics expertise, allowed us to build this complex and unique instrument that is now part of the ALPHA experiment."

Dr Niels Madsen notes: "Trapping of anti-hydrogen is a major breakthrough in antimatter physics. Having the anti-atoms trapped will allow for comparisons of matter and anti-matter to a level that until now would have been considered wishful thinking."

The initiative is expected to run for several years, with ALPHA commencing tests on anti-hydrogen atoms in around five years time.
Notes for Editors

Key EPSRC-funded projects researching into anti-hydrogen and involving Swansea University include: 'The spectroscopy of anti-hydrogen' (total EPSRC funding £1.98m), 'Anti-hydrogen physics' (total EPSRC funding £0.66m), 'Anti-hydrogen trapping and plasma control' (total EPSRC funding £0.37m), 'Theory of anti-hydrogen atoms' (total EPSRC funding £0.41m), and 'Simulations of anti-hydrogen formation' (total EPSRC funding £8k).

* The ALPHA (Anti-hydrogen Laser PHysics Apparatus) project at CERN (the European Organisation for Nuclear Research based in Geneva) is the successor of ATHENA (see below). ALPHA aims to study anti-hydrogen atoms and compare them with hydrogen atoms:

** The CERN project ATHENA achieved the first controlled production of anti-hydrogen atoms. Professor Mike Charlton and his team at Swansea University also played a key role in this major breakthrough with support from the Engineering and Physical Sciences Research Council.

*** In physics, a 'magnetic moment' is defined as the product of a magnet's pole strength and the distance between its poles.

The existence of anti-matter was first predicted mathematically in the 1920s prior to the detection of the positron (the anti-particle of the electron) in cosmic rays in the 1930s and the discovery of the anti-proton in particle physics accelerator laboratories in the 1950s.

For more information on Swansea University visit:

And for more information on the University of Liverpool visit:


EPSRC is the main UK government agency for funding research and training in engineering and the physical sciences, investing more than £850 million a year in a broad range of subjects - from mathematics to materials science, and from information technology to structural engineering. For more information, contact:

Professor Mike Charlton, Department of Physics, Swansea University, tel: 01792 295372, Email:

Or the EPSRC Press Office on 01793 444404 or e-mail: images are also available from the EPSRC Press Office

Image details:-
MikeCharlton.jpg, suggested caption: Professor Mike Charlton

Catching trap.jpg, suggested caption: The right end of a catching trap (Credit: N Madsen)

A selection of images are also available here: please credit any images used to N Madsen

Engineering and Physical Sciences Research Council

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