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Focus: The Coolest Antiprotons

Lisa Grossman

Published Jul 2, 2010• 0 citations
OpenAlex

Abstract

The coldest antiprotons ever produced–which reached 9 kelvin–were cooled with a tried-and-true method for neutral atoms. The result is an essential step on the road to studying antihydrogen.

Related papers

The Coolest Antiprotons

Lisa Grossman

The coldest antiprotons ever produced–which reached 9 kelvin–were cooled with a tried-and-true method for neutral atoms. The result is an essential step on the road to studying antihydrogen.

Focus•Jul 1, 2010•5 citations

Trapping of antiprotons -- a first step on the way to antihydrogen

Michael H. Holzscheiter

A first step towards producing and effectively utilizing antihydrogen atoms consists of trapping antiprotons. The immediate next step must then be to control, i.e. trap the produced antihydrogen. The current state of the art in trapping antiprotons and positrons is reviewed, and the challenges in trapping the resulting neutral particles are discussed.

•Jul 1, 1993•0 citations

Producing ultracold and trappable antihydrogen atoms

S. X. Hu

Both experiments and simulations have shown that the temperature of antihydrogen atoms $(\overline{\mathrm{H}})$ formed in a strongly magnetized positron-antiproton plasma is mainly determined by the heavy particles' temperature. A routine to keep cooling antiprotons $(\overline{p})$ by using ultracold $(<1\phantom{\rule{0.3em}{0ex}}\mathrm{K})$ electrons is proposed under attainable experimental conditions. When cold positrons are loaded into such a low-temperature electron-antiproton mixture, ultracold antihydrogen atoms can be produced at a temperature below $\ensuremath{\sim}1\phantom{\rule{0.3em}{0ex}}\mathrm{K}$. Our large-scale molecular-dynamics simulations, which involve $20\phantom{\rule{0.2em}{0ex}}000$ particles (${e}^{\ensuremath{-}}$, ${e}^{+}$, and $\overline{p}$) evolving up to $1\phantom{\rule{0.3em}{0ex}}\mathrm{\ensuremath{\mu}}\mathrm{s}$, have confirmed the generation of trappable $\overline{\mathrm{H}}$ atoms.

Physical Review A•Jan 29, 2007•4 citations

Advances in Antihydrogen Physics

M. Charlton, Dirk Peter van der Werf

The creation of cold antihydrogen atoms by the controlled combination of positrons and antiprotons has opened up a new window on fundamental physics. More recently, techniques have been developed that allow some antihydrogen atoms to be created at low enough kinetic energies that they can be held inside magnetic minimum neutral atom traps. With confinement times of many minutes possible, it has become feasible to perform experiments to probe the properties of the antiatom for the first time. We review the experimental progress in this area, outline some of the motivation for studying basic aspects of antimatter physics and provide an outlook of where we might expect this field to go in the coming years.

Science Progress•Mar 1, 2015•18 citations

Evaporative cooling of antiprotons and efforts to trap antihydrogen

Gorm Bruun Andresen

Evaporative cooling has proven to be an invaluable technique in atomic physics, allowing for the study of effects such as Bose-Einstein condensation. One main topic of this thesis is the first application of evaporative cooling to cold non-neutral plasmas stored in an ion trap. We (the ALPHA collaboration) have achieved cooling of a cloud of antiprotons to a temperature as low as 9 K, two orders of magnitude lowerthan ever directly measured previously. The measurements are well-described by appropriate rate equations for the temperature and number of particles. The technique has direct application to the ongoing attempts to produce trapped samples of antihydrogen. In these experiments the maximum trap depths are ex tremely shallow (~0.6 K for ground state atoms), and careful control of the trapped antiprotons and positrons used to form the (anti)atoms is essential to succes. Since 2006 powerful tools to diagnose and manipulate the antiproton and positron plasmas in the ALPHA apparatus have been developed and used in attempts to trap antihydrogen. These efforts are the second main topic of this thesis.

•Jan 1, 2010•3 citations

Antiproton-Hydrogen and Antihydrogen-Hydrogen annihilation at sub-kelvin temperatures

Alexei Yu. Voronin, Jaume Carbonell

Few-body systems. Supplementum•Jan 1, 1999•1 citation
Both experiments and simulations have shown that the temperature of antihydrogen atoms (H‾)(\overline{\mathrm{H}})(H) formed in a strongly magnetized positron-antiproton plasma is mainly determined by the heavy particles' temperature. A routine to keep cooling antiprotons (p‾)(\overline{p})(p​) by using ultracold (<1K)(<1\phantom{\rule{0.3em}{0ex}}\mathrm{K})(<1K) electrons is proposed under attainable experimental conditions. When cold positrons are loaded into such a low-temperature electron-antiproton mixture, ultracold antihydrogen atoms can be produced at a temperature below $\ensuremath{\sim}1\phantom{\rule{0.3em}{0ex}}\mathrm{K}$. Our large-scale molecular-dynamics simulations, which involve 2000020\phantom{\rule{0.2em}{0ex}}00020000 particles (${e}^{\ensuremath{-}}$, e+{e}^{+}e+, and p‾\overline{p}p​) evolving up to $1\phantom{\rule{0.3em}{0ex}}\mathrm{\ensuremath{\mu}}\mathrm{s}$, have confirmed the generation of trappable H‾\overline{\mathrm{H}}H atoms.
The creation of cold antihydrogen atoms by the controlled combination of positrons and antiprotons has opened up a new window on fundamental physics. More recently, techniques have been developed that allow some antihydrogen atoms to be created at low enough kinetic energies that they can be held inside magnetic minimum neutral atom traps. With confinement times of many minutes possible, it has become feasible to perform experiments to probe the properties of the antiatom for the first time. We review the experimental progress in this area, outline some of the motivation for studying basic aspects of antimatter physics and provide an outlook of where we might expect this field to go in the coming years.
Evaporative cooling has proven to be an invaluable technique in atomic physics, allowing for the study of effects such as Bose-Einstein condensation. One main topic of this thesis is the first application of evaporative cooling to cold non-neutral plasmas stored in an ion trap. We (the ALPHA collaboration) have achieved cooling of a cloud of antiprotons to a temperature as low as 9 K, two orders of magnitude lowerthan ever directly measured previously. The measurements are well-described by appropriate rate equations for the temperature and number of particles. The technique has direct application to the ongoing attempts to produce trapped samples of antihydrogen. In these experiments the maximum trap depths are ex tremely shallow (~0.6 K for ground state atoms), and careful control of the trapped antiprotons and positrons used to form the (anti)atoms is essential to succes. Since 2006 powerful tools to diagnose and manipulate the antiproton and positron plasmas in the ALPHA apparatus have been developed and used in attempts to trap antihydrogen. These efforts are the second main topic of this thesis.