An improved limit on the charge of antihydrogen from stochastic acceleration

Ahmadi, Mostafa; Baquero-Ruiz, M.; Bertsche, W.; Butler, E.; Capra, A.; Carruth, C.; Cesar, C. L.; Charlton, M.; Charman, Andrew; Eriksson, S.; Evans, L. T.; Evetts, N.; Fajans, J.; Friesen, T.; Fujiwara, M.; Gill, D. R.; Gutiérrez, A.; Hangst, J. S.; Hardy, W. N.; Hayden, M. E.; Isaac, C. A.; Ishida, Akira; Jones, S. A.; Jonsell, Svante; Kurchaninov, L. L.; Madsen, N.; Maxwell, D.; McKenna, J. T. K.; Menary, S.; Michan, J. M.; Momose, Takamasa; Munich, J. J.; Nolan, P.; Olchanski, K.; Olin, Å.; Povilus, A.; Pusa, P.; Rasmussen, C. Ø.; Robicheaux, F.; Sacramento, R. L.; Sameed, M.; Sarid, E.; Silveira, D. M.; So, C.; Tharp, T. D.; Thompson, R. I.; Werf, D. P. van der; Wurtele, J. S.; Zhmoginov, Andrey

doi:10.1038/nature16491

Cited by 49 publications

(39 citation statements)

References 33 publications

(7 reference statements)

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“…To determine the signal events in the 1.5-s and 2 × 300-s observation windows, we require two different suppression techniques. We tune the MVA for the two windows in a similar manner to that used in a recent study of the neutrality of antihydrogen 12 . Annihilation events are distinguished from background events (primarily cosmic rays) by their distinctive topologies.…”

Section: Methodsmentioning

confidence: 99%

“…This feat was later repeated [7][8][9] , and in 2010 antihydrogen was successfully trapped 3 to facilitate its study. It was subsequently shown that antiatoms could be held 4 for up to 1,000 s, and various measurements have been performed on antihydrogen in the context of tests of CPT symmetry [10][11][12] or gravitational studies 13 .…”

mentioning

confidence: 99%

“…The particle manipulations that are necessary to produce trappable antihydrogen atoms have been described elsewhere 3,4,17 ; we note only that recent innovations (Methods) in these techniques have provided a large improvement in the number of trapped anti-atoms available per trial compared to the best previous result 12 . The antihydrogen production method involves a new technique in which we 'stack' anti-atoms resulting from two successive mixing cycles, which originate from independent shots of antiprotons from the antiproton decelerator and accumulations of positrons.…”

mentioning

confidence: 99%

“…The antihydrogen production method involves a new technique in which we 'stack' anti-atoms resulting from two successive mixing cycles, which originate from independent shots of antiprotons from the antiproton decelerator and accumulations of positrons. We trapped on average about 14 anti-atoms per trial, compared to 1.2 in previous work 12 .…”

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confidence: 99%

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Observation of the 1S–2S transition in trapped antihydrogen

Ahmadi

Alves

Baker

et al. 2016

Nature

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126

140

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The spectrum of the hydrogen atom has played a central part in fundamental physics over the past 200 years. Historical examples of its importance include the wavelength measurements of absorption lines in the solar spectrum by Fraunhofer, the identification of transition lines by Balmer, Lyman and others, the empirical description of allowed wavelengths by Rydberg, the quantum model of Bohr, the capability of quantum electrodynamics to precisely predict transition frequencies, and modern measurements of the 1S-2S transition by Hänsch 1 to a precision of a few parts in 10 15 . Recent technological advances have allowed us to focus on antihydrogen-the antimatter equivalent of hydrogen 2-4 . The Standard Model predicts that there should have been equal amounts of matter and antimatter in the primordial Universe after the Big Bang, but today's Universe is observed to consist almost entirely of ordinary matter. This motivates the study of antimatter, to see if there is a small asymmetry in the laws of physics that govern the two types of matter. In particular, the CPT (charge conjugation, parity reversal and time reversal) theorem, a cornerstone of the Standard Model, requires that hydrogen and antihydrogen have the same spectrum. Here we report the observation of the 1S-2S transition in magnetically trapped atoms of antihydrogen. We determine that the frequency of the transition, which is driven by two photons from a laser at 243 nanometres, is consistent with that expected for hydrogen in the same environment. This laser excitation of a quantum state of an atom of antimatter represents the most precise measurement performed on an anti-atom. Our result is consistent with CPT invariance at a relative precision of about 2 × 10 −10 .

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Section: Methodsmentioning

confidence: 99%

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confidence: 99%

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confidence: 99%

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confidence: 99%

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Observation of the 1S–2S transition in trapped antihydrogen

Ahmadi

Alves

Baker

et al. 2016

Nature

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126

140

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“…Recent advances include trapping of antihydrogen atoms in magnetic traps [2][3][4][5], the creation of an antihydrogen beam [6,7], a first investigation of its internal structure [8], a rudimentary investigation of its gravitational mass [9], and high-precision measurements of its charge [10,11].…”

Section: Introductionmentioning

confidence: 99%

The Role of Antihydrogen Formation in the Radial Transport of Antiprotons in Positron Plasmas

Jonsell

Charlton

Werf

2017

Proceedings of the 12th International Conference on Low Energy Antiproton Physics (LEAP2016)

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Simulations have been performed of the radial transport of antiprotons in positron plasmas under ambient conditions typical of those used in antihydrogen formation experiments in Penning traps. The simulations were performed using classical trajectories of both antiprotons and surrounding positrons with randomized initial conditions. In addition, friction and fluctuation forces on the antiproton due to interaction with the positron plasma were included. This gives rise to both axial and radial diffusion of the antiprotons at a rate given by the magnetic field, the positron temperature and the plasma density, and the parameter range explored includes at least two values of each. As the antiprotons travel through the positron plasma they undergo repeated cycles of antihydrogen formation and reionization. We find that when these effects are added to the simulations the properties of the radial diffusion alter dramatically, even changing from normal to anomalous diffusion. We attribute this to the azimuthal drift of the antiprotons in the crossed magnetic (from the trap) and electric fields (from the space charge of the plasma). When the antiprotons are neutralised through antihydrogen formation this drift is temporarily interrupted, and the antiproton (carrying a positron) continues in the tangential direction. On average this motion will give an increase of the radial position of the antiproton, relative the trap axis. At low positron plasma temperatures, repeated cycles of antihydrogen formation and destruction are the dominant source of radial (cross magnetic field) transport. On time scales of a few milliseconds (depending on plasma parameters) the antiprotons will reach the edge of the cylindrical plasma, where the radial transport will cease, and thus the antiprotons will accumulate there.

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Searches for New Physics

Safronova

2023

Springer Handbook of Atomic, Molecular, and Optical Physics

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An improved limit on the charge of antihydrogen from stochastic acceleration

Cited by 49 publications

References 33 publications

Observation of the 1S–2S transition in trapped antihydrogen

Observation of the 1S–2S transition in trapped antihydrogen

The Role of Antihydrogen Formation in the Radial Transport of Antiprotons in Positron Plasmas

Searches for New Physics

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