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Collisions involving antiparticles

Gaetana Laricchia, M. Charlton

Recent advances and future prospects in the study of atomic and molecular collisions using monoenergetic beams of positrons, positronium and antiprotons are considered as well as current efforts towards the synthesis of cold antihydrogen.

Philosophical Transactions of the Royal Society A Mathematical Physical and Engineering SciencesMay 15, 19999 citations

Positron cooling of antiprotons: precursor of recombination

Jun Tan, J. Estrada, P. Yesley +15 more

APSMay 1, 20010 citations

Atomic spectroscopy and collisions using slow antiprotons

R. Funakoshi, Kunihiro Suzuki, Christoph Scheidenberger +49 more

Oct 24, 199710 citations

Be+-Assisted Antihydrogen Synthesis and Trapping

Maria Eduarda Fagundes Gonçalves

Antihydrogen, the bound state of a positron and an antiproton, is a uniquely well-suited system for testing fundamental symmetries between matter and antimatter. The Antihydrogen Laser Physics Apparatus (ALPHA collaboration) synthesises antihydrogen atoms by slowly merging cold non-neutral positron and antiproton plasmas and traps the antiatoms in a magnetic minimum trap. While trapping eﬃciency has improved since its ﬁrst demonstration in 2010, it plateaued after 2017.In ALPHA’s experimental conditions, antihydrogen is predominantly formed via three-body recombination, which has been theoretically and experimentally shown to strongly depend on the temperature of the positron plasma: lower positron temperatures yield higher antihydrogen trapping rates. In the ALPHA-2 trap, positrons alone reach a lower temperature limit of 15−20 K. The implementation of sympathetic cooling of positrons through collisions with laser-cooled Be+ions enabled stable lowering of these temperatures to below 10 K. This thesis describes the work towards antihydrogen synthesis with positrons prepared using this cooling method. A novel ion plasma preparation technique was developed to improve reproducibility, and a sophisticated control system with automated beam steering was implemented to ensure long-term operational stability. Moreover, the ﬁrst demonstration of sympathetic cooling of positrons to < 10 K in a radially asymmetric magnetic ﬁeld was carried out. Culminating in the ﬁrst Be+-assisted antihydrogen synthesis and trapping. Careful optimisation of this technique resulted in a near eightfold increase in the antihydrogen trapping rate, and allowed for systematic studies of three-body recombination that were not possible before its implementation. Overall, this technique represents a paradigm shift for the ALPHA physics programme and provides a deeper understanding of antihydrogen synthesis, opening new avenues for precision studies of antimatter.Antihydrogen, the bound state of a positron and an antiproton, is a uniquely well-suited system for testing fundamental symmetries between matter and antimatter. The Antihydrogen Laser Physics Apparatus (ALPHA collaboration) synthesises antihydrogen atoms by slowly merging cold non-neutral positron and antiproton plasmas and traps the antiatoms in a magnetic minimum trap. While trapping eﬃciency has improved since its ﬁrst demonstration in 2010, it plateaued after 2017.In ALPHA’s experimental conditions, antihydrogen is predominantly formed via three-body recombination, which has been theoretically and experimentally shown to strongly depend on the temperature of the positron plasma: lower positron temperatures yield higher antihydrogen trapping rates. In the ALPHA-2 trap, positrons alone reach a lower temperature limit of 15−20 K. The implementation of sympathetic cooling of positrons through collisions with laser-cooled Be+ions enabled stable lowering of these temperatures to below 10 K. This thesis describes the work towards antihydrogen synthesis with positrons prepared using this cooling method. A novel ion plasma preparation technique was developed to improve reproducibility, and a sophisticated control system with automated beam steering was implemented to ensure long-term operational stability. Moreover, the ﬁrst demonstration of sympathetic cooling of positrons to < 10 K in a radially asymmetric magnetic ﬁeld was carried out. Culminating in the ﬁrst Be+-assisted antihydrogen synthesis and trapping. Careful optimisation of this technique resulted in a near eightfold increase in the antihydrogen trapping rate, and allowed for systematic studies of three-body recombination that were not possible before its implementation. Overall, this technique represents a paradigm shift for the ALPHA physics programme and provides a deeper understanding of antihydrogen synthesis, opening new avenues for precision studies of antimatter.

Jan 23, 20260 citations

Manipulation of ultraslow antiprotons and first application to atomic collisions

祐吾永田

Jan 1, 20082 citations

Towards a gravity measurement on cold antimatter atoms

R. Caravita, Stefano Aghion, C. Amsler +80 more

The present status of the AEGIS experiment at CERN (AD-06), on the way of forming anti-hydrogen for a first gravity measurement, is reviewed.Recent results in trapping and cooling positrons and antiprotons in the main electromagnetic traps are presented, including the storage time measurement obtained during the 2014 run with antiprotons, the observation of centrifugal separation of a mixed antiproton/electron plasma and positron accumulation and transfer results obtained during 2015.

Il Nuovo Cimento CJun 27, 20160 citations

5. Atomic Collision Experiments using Slow Antiprotons( From Synthesis To Physics of Anti-Hydrogen-Cooling, Recombination, and Trapping of Antiprotons and Positrons-)

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5. Atomic Collision Experiments using Slow Antiprotons( From Synthesis To Physics of Anti-Hydrogen-Cooling, Recombination, and Trapping of Antiprotons and Positrons-)

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