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AEgIS (Antimatter experiment: gravity, interferometry, spectroscopy) is an experiment approved by CERN with the goal of studying antihydrogen physics. In AEgIS, antihydrogen will be produced by charge exchange reactions of cold antiprotons with positronium atoms excited in a Rydberg state (n > 20). In the first phase of the experiment, controlled acceleration by an electric field gradient (Stark effect) and subsequent measurement of free fall in a Moire deflectometer will allow a test of the weak equivalence principle. In a second phase, the antihydrogen will be slowed, confined, and laser-cooled to perform CPT studies and detailed spectroscopy. In the present work, after a general description of the experiment, the present status of advancement will be reviewed, with special attention to the production and excitation of positronium atoms. PACS Nos: 03.75.Dg, 06.30.Gv, 25.43.+t, 34.80.Lx AEgIS (Experience sur l'Antimatiere: Gravite;, Interfeerometrie, Spectromeetrie) est une experience approuvee par le CERN qui vise une etude globale de la physique de l'anti-hydrogene. Dans AEgIS, l'anti-hydrogene sera produit par des reactions d'echange de charges d'anti-protons froids avec des atomes de positronium excitees dans un etat de Rydberg (n > 20). Dans la premiere phase de l'experience, l'acceileration est controlee par un gradient de champ electrique (effet Stark); une mesure subsequente en chute libre dans un deflectometre de Moire nous fournira un test du principe d'equivalence faible. Dans une deuxieme phase, l'anti-hydrogene sera ralenti, confine et refroidi par laser pour des etudes de CPT et de spectroscopie de precision. Apres une description geenerale de l'experience, nous passons ici en revue l'etat d'avancement des travaux en accordant une attention particuliere a la production et l'excitation des atomes de positronium. [Traduit par la Redaction], 1. Introduction A new generation of antimatter experiments has been opened after the first experiments of antihydrogen production in laboratory conditions at the CERN laboratory [1] and at Fermilab [2]. [...]

Antihydrogen spectroscopy promises precise tests of the symmetry of matter and antimatter, and can possibly offer new insights into the baryon asymmetry of the universe. Antihydrogen is, however, difficult to synthesize and is produced only in small quantities. The ALPHA collaboration is therefore pursuing a path towards trapping cold antihydrogen to permit the use of precision atomic physics tools to carry out comparisons of antihydrogen and hydrogen. ALPHA has addressed these challenges. Control of the plasma sizes has helped to lower the influence of the multipole field used in the neutral atom trap, and thus lowered the temperature of the created atoms. Finally, the first systematic attempt to identify trapped antihydrogen in our system is discussed. This discussion includes special techniques for fast release of the trapped antiatoms, as well as a silicon vertex detector to identify antiproton annihilations. The silicon detector reduces the background of annihilations, including background from antiprotons that can be mirror trapped in the fields of the neutral atom trap. A description of how to differentiate between these events and those resulting from trapped antihydrogen atoms is also included. PACS Nos: 25.43.+t, 34.80.Lx, 36.10.-k, 37.10.Gh La spectroscopie de l'anti-hydrogene promet des tests precieux de la symeetrie entre matiere et antimatiere dans l'univers. Cependant, l'anti-hydrogene est difficile a synthetiser et il n'est produit qu'en petite quantite. Le groupe de collaborateurs ALPHA poursuit donc des travaux pour capturer de l'anti-hydrogene froid afin de permettre l'utilisation d'outils precis de mesure en physique atomique pour comparer l'anti-hydrogene avec l'hydrogene. Nous montrons comment ALPHA s'est attaque a cette tache et comment le controle du volume de plasma a aide; a diminuer l'influence des champs multipolaires utilises dans le piege pour atomes neutres et ainsi abaisser la temperature des atomes produits. Finalement, nous discutons le premier essai systeematique pour identifier l'anti-hydrogene piege dans notre systeme. Ceci inclut des techniques speciales pour relacher rapidement les anti-atomes pieges, ainsi qu'un detecteur au silicium pour identifier l'annihilation de l'anti-proton. Nous avons utilise: le detecteur au silicium pour reduire le fond d'annihilation, incluant celui produit par les anti-protons qui peuvent etre dans le piege miroir des champs du piege a atomes neutres. Nous decrivons aussi comment nous pouvons diffeerentier entre ces eveenements et ceux qui resultent des atomes d'anti-hydrogene piegees. [Traduit par la Redaction], 1. Introduction Antihydrogen, the antimatter counterpart of hydrogen, holds the promise of precise tests of the CPT theorem and the weak equivalence principle through direct comparisons with hydrogen [1]. Since [...]

Cooling antihydrogen atoms is important for future experiments both to test the fundamental CPT symmetry by high resolution laser spectroscopy and also to measure the gravitational acceleration of antimatter. Laser cooling of antihydrogen can be done on the strong 1S-2P transition at the wavelength of Lyman-alpha (121.6 nm). A continuous wave laser at the Lyman-alpha wavelength based on solid-state fundamental lasers is described. By using a two-photon and a near one-photon resonance a scan across the whole phase matching curve of the four-wave mixing process is possible. Furthermore the influence of the beam profile of one fundamental beam on the four-wave mixing process is studied. PACS Nos: 36.20.-k, 37.10.De, 42.65.Ky Le refroidissement des atomes d'anti-hydrogene est important dans les experiences a venir pour verifier la symetrie fondamentale CPT par spectroscopie laser a haute resolution et pour mesurer l'acceleeration gravitationnelle de l'antimatiere. Le refroidissement laser de l'anti-hydrogene peut se faire sur la transition intense 1S-2P a la longueur d'onde Lyman alpha (121.6 nm). Nous deecrivons un laser continu a la longueur d'onde Lyman alpha, dont les elements sont des lasers a solide. En utilisant des resonances a deux photons et a pres d'un photon, un balayage sur toute la courbe d'adaptation de phase du melange a quatre ondes devient possible. Nous etudions aussi l'influence du profil d'un faisceau eelesmentaire sur le meecanisme de melange a quatre ondes. [Traduit par la Redaction], 1. Introduction Future high resolution laser spectroscopy of antihydrogen in a magnetic trap can provide very stringent tests of the fundamental symmetry between matter and antimatter (CPT symmetry) [1]. The [...]

Author(s): Elizabeth Gibney Antimatter is notoriously volatile, but physicists have that they are now starting to harness it as a tool for the first time. In a project that began [...]

Author(s): Elizabeth Gibney [1] In a high-ceilinged hangar at CERN, six rival experiments are racing to understand the nature of one of the Universe's most elusive materials. They sit just [...]

The Alpha Magnetic Spectrometer (AMS) is a particle physics detector designed to measure charged cosmic ray spectra up to the TV region, with high-energy photon detection capability up to few hundred GeV. AMS is a superconducting spectrometer with large acceptance, long duration (at least three years for the magnet) and state of the art particle identification techniques. AMS will investigate the composition of cosmic rays with high statistics and provide the most sensitive search for the existence of antimatter nuclei and for the nature of dark matter. The detector is being constructed with an eight-layer Silicon Tracker inside a large superconducting magnet, providing a ~0.8 [Tm.sup.2] bending power and an acceptance of ~0.4 [m.sup.2] sr. A Transition Radiation Detector and a three-dimensional Electromagnetic Calorimeter allow for electron, positron and photon identification, while a Time of Flight scintillating system and a Ring Image Cerenkov detector perform independent velocity measurements. This complex apparatus will identify and measure nuclei up to Iron. We will describe the overall detector construction and performance, which is due to be completed by 2006. The detector will be installed on ISS (International Space Station) in 2008. Index Terms--Anti-matter, cosmic rays, dark matter, neutralino, space detector, space station, superconducting spectrometer.

Author Affiliations: Baby monkey, antimatter puzzle and Alzheimer's disappointment EVENTS Scientists join huge Brexit protest Scientists took to the streets of London on 23 March as part of a major [...], The week in science: 22-28 March 2019. The week in science: 22-28 March 2019.

The conceptual design of the spectrometer and the scientific goals of the AMS experiment, will be presented here as well as the measured performances for minimum ionising particles using ground level cosmic-rays and reconstructed events from space. The first results of a test done with relativistic carbon ions at GSI (Darmstadt) will also be given. A preliminary version of the AMS apparatus flew on June 1998 on shuttle mission STS-91. In 2002 the complete system will be installed on the space station Alpha and it will take data for three years.

Antihydrogen has recently been produced in CERN. I discuss the original motivation for the study of antimatter, and describe the large, but as yet unsuccessful attempt to produce cold antihydrogen confined to a trap, where it can be studied spectroscopically, and compared with ordinary hydrogen. I also describe the experiment at CERN, which produced [approximately]11 atoms of antihydrogen moving at 90% of the speed of light, circumstances that make precision spectroscopy difficult.

After some general remarks about 'big bang' cosmology it is pointed out how, in order to explain why there is matter but no antimatter in the observed Universe, reactions involving violation of baryon number must have taken place at early times. It turns out that processes violating time reversal invariance are also necessary. The article surveys the subjects of the discrete symmetries (space inversion, time reversal and particle - antiparticle transformation) and their violation in elementary-particle physics, and grand unified theories, which predict baryon number violation. A simple model is then presented which could account qualitatively for the dominance of matter over antimatter in the Universe. It is pointed out that grand unified theories are not the only providers of a mechanism for baryon number violation; one other possibility, the sphaleron, is briefly explained.

Author(s): Elizabeth Gibney Author Affiliations: Physicists plan antimatter's first outing -- in a van Antiprotons present a unique way to study the radioactive elements produced at CERN's ISOLDE ion-beam facility. [...], Researchers intend to transport the elusive material between labs and use it to study the strange behaviour of rare radioactive nuclei. Researchers intend to transport the elusive material between labs and use it to study the strange behaviour of rare radioactive nuclei.

The charge neutrality of the antimatter atom antihydrogen has been confirmed with unprecedented accuracy, paving the way for experiments that could simultaneously solve several of physics' biggest mysteries. See Letter [...]

The tools and ingredients for making this first atom of antimatter are in hand; now researchers need to choose the right recipe Dreams of antimatter have been troubling physicists' sleep [...]

Author Affiliations: The proton just got lighter The proton is slightly lighter than previously believed, according to the most accurate measurement so far of this particle's mass. Protons weigh slightly [...], Most precise measurement so far of tiny particle's mass could help explain antimatter conundrum. Most precise measurement so far of tiny particle's mass could help explain antimatter conundrum.

One major frustration the universe inflicts on physicists is a serious shortage of antimatter. It should be fascinating stuff--looking-glass atoms with negatively charged nuclei surrounded by clouds of positive charge, [...]

In a 1991 News & Views article (1) on the ingenious means by which positrons, the antiparticle counterpart of electrons, were used in materials science, John Maddox, the then editor [...]