- Published on 03 May 2018
Improving the spatial compression of a mixed matter-antimatter trapped plasma brings us one step closer to grasping the acceleration of antimatter due to Earth’s gravity
An international team of physicists studying antimatter have now derived an improved way of spatially compressing a state of matter called non-neutral plasma, which is made up of a type of antimatter particles, called antiprotons, trapped together with matter particles, like electrons. The new compression solution, which is based on rotating the plasma in a trapped cavity using centrifugal forces like a salad spinner, is more effective than all previous approaches. In this study published in EPJ D, the team shows that, under specific conditions, a ten-fold compression of the size of the antiproton cloud, down to a radius of only 0.17 millimetres, is possible. These findings can be applied in the field of low-energy antimatter research, charged particle traps and plasma physics. Further, this work is part of a larger research project, called AEgIS, which is intended to achieve the first direct measurement of the gravitational effect on an antimatter system. The ultimate goal of the project, which is being pursued at CERN, the Particle Physics Laboratory in Geneva, Switzerland, is to measure the acceleration of antimatter—namely antihydrogen—due to Earth’s gravity with a precision of 1%.
In this study, the authors use a plasma manipulation method called the rotating wall, which they have optimised. They employ specially tailored electrical fields, changing in time and space inside the trap volume, to induce modification of the rotation frequency. Due to the resultant centrifugal force, the plasma rotates faster and is compressed.
Specifically, the proportion of trapped antiprotons under compression is initially less than 0.1% of the electrons. During the procedure the number of electrons is reduced so as to maximise compression. To do so, antiprotons and electrons trapped in the same volume rotate around the trap axis. Interestingly, for a given number of particles, the faster the rotation, the higher their spatial density becomes as the plasma radius continues to shrink.
Stefano Aghion, Claude Amsler, Germano Bonomi, Roberto S. Brusa, Massimo Caccia, Ruggero Caravita, Fabrizio Castelli, Giovanni Cerchiari, Daniel Comparat, Giovanni Consolati, Andrea Demetrio, Lea Di Noto, Michael Doser, Craig Evans, Mattia Fani, Rafael Ferragut, Julian Fesel, Andrea Fontana, Sebastian Gerber, Marco Giammarchi, Angela Gligorova, Francesco Guatieri, Stefan Haider, Alexander Hinterberger, Helga Holmestad, Alban Kellerbauer, Olga Khalidova, Daniel Krasnick, Vittorio Lagomarsino, Pierre Lansonneur, Patrice Lebrun, Chloé Malbrunot, Sebastiano Mariazzi, Johann Marton, Victor Matveev, Zeudi Mazzotta, Simon R. Muller, Giancarlo Nebbia, Patrick Nedelec, Markus Oberthaler, Nicola Pacifico, Davide Pagano, Luca Penasa, Vojtech Petracek, Francesco Prelz, Marco Prevedelli, Benjamin Rienaecker, Jacques Robert, Ole M. Røhne, Alberto Rotondi, Heidi Sandaker, Romualdo Santoro, Lillian Smestad, Fiodor Sorrentino, Gemma Testera, Ingmari C. Tietje, Eberhard Widmann, Pauline Yzombard, Christian Zimmer, Johann Zmeska, Nicola Zurlo, and Massimiliano Antonello (2018),
Compression of a mixed antiproton and electron non-neutral plasma to high densities,
European Physical Journal D, DOI: 10.1140/epjd/e2018-80617-x