1
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Anderson EK, Baker CJ, Bertsche W, Bhatt NM, Bonomi G, Capra A, Carli I, Cesar CL, Charlton M, Christensen A, Collister R, Cridland Mathad A, Duque Quiceno D, Eriksson S, Evans A, Evetts N, Fabbri S, Fajans J, Ferwerda A, Friesen T, Fujiwara MC, Gill DR, Golino LM, Gomes Gonçalves MB, Grandemange P, Granum P, Hangst JS, Hayden ME, Hodgkinson D, Hunter ED, Isaac CA, Jimenez AJU, Johnson MA, Jones JM, Jones SA, Jonsell S, Khramov A, Madsen N, Martin L, Massacret N, Maxwell D, McKenna JTK, Menary S, Momose T, Mostamand M, Mullan PS, Nauta J, Olchanski K, Oliveira AN, Peszka J, Powell A, Rasmussen CØ, Robicheaux F, Sacramento RL, Sameed M, Sarid E, Schoonwater J, Silveira DM, Singh J, Smith G, So C, Stracka S, Stutter G, Tharp TD, Thompson KA, Thompson RI, Thorpe-Woods E, Torkzaban C, Urioni M, Woosaree P, Wurtele JS. Observation of the effect of gravity on the motion of antimatter. Nature 2023; 621:716-722. [PMID: 37758891 PMCID: PMC10533407 DOI: 10.1038/s41586-023-06527-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2023] [Accepted: 08/09/2023] [Indexed: 09/29/2023]
Abstract
Einstein's general theory of relativity from 19151 remains the most successful description of gravitation. From the 1919 solar eclipse2 to the observation of gravitational waves3, the theory has passed many crucial experimental tests. However, the evolving concepts of dark matter and dark energy illustrate that there is much to be learned about the gravitating content of the universe. Singularities in the general theory of relativity and the lack of a quantum theory of gravity suggest that our picture is incomplete. It is thus prudent to explore gravity in exotic physical systems. Antimatter was unknown to Einstein in 1915. Dirac's theory4 appeared in 1928; the positron was observed5 in 1932. There has since been much speculation about gravity and antimatter. The theoretical consensus is that any laboratory mass must be attracted6 by the Earth, although some authors have considered the cosmological consequences if antimatter should be repelled by matter7-10. In the general theory of relativity, the weak equivalence principle (WEP) requires that all masses react identically to gravity, independent of their internal structure. Here we show that antihydrogen atoms, released from magnetic confinement in the ALPHA-g apparatus, behave in a way consistent with gravitational attraction to the Earth. Repulsive 'antigravity' is ruled out in this case. This experiment paves the way for precision studies of the magnitude of the gravitational acceleration between anti-atoms and the Earth to test the WEP.
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Affiliation(s)
- E K Anderson
- Department of Physics and Astronomy, Aarhus University, Aarhus, Denmark
| | - C J Baker
- Department of Physics, Faculty of Science and Engineering, Swansea University, Swansea, UK
| | - W Bertsche
- School of Physics and Astronomy, University of Manchester, Manchester, UK.
- Cockcroft Institute, Sci-Tech Daresbury, Warrington, UK.
| | - N M Bhatt
- Department of Physics, Faculty of Science and Engineering, Swansea University, Swansea, UK
| | - G Bonomi
- University of Brescia, Brescia and INFN Pavia, Pavia, Italy
| | - A Capra
- TRIUMF, Vancouver, British Columbia, Canada
| | - I Carli
- TRIUMF, Vancouver, British Columbia, Canada
| | - C L Cesar
- Instituto de Fisica, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - M Charlton
- Department of Physics, Faculty of Science and Engineering, Swansea University, Swansea, UK
| | - A Christensen
- Department of Physics, University of California at Berkeley, Berkeley, CA, USA
| | - R Collister
- TRIUMF, Vancouver, British Columbia, Canada
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia, Canada
| | - A Cridland Mathad
- Department of Physics, Faculty of Science and Engineering, Swansea University, Swansea, UK
| | - D Duque Quiceno
- TRIUMF, Vancouver, British Columbia, Canada
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia, Canada
| | - S Eriksson
- Department of Physics, Faculty of Science and Engineering, Swansea University, Swansea, UK
| | - A Evans
- TRIUMF, Vancouver, British Columbia, Canada
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia, Canada
| | - N Evetts
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia, Canada
| | - S Fabbri
- School of Physics and Astronomy, University of Manchester, Manchester, UK
- Accelerator and Technology Sector, CERN, Geneva, Switzerland
| | - J Fajans
- Department of Physics, University of California at Berkeley, Berkeley, CA, USA.
| | - A Ferwerda
- Department of Physics and Astronomy, York University, Toronto, Ontario, Canada
| | - T Friesen
- Department of Physics and Astronomy, University of Calgary, Calgary, Alberta, Canada
| | | | - D R Gill
- TRIUMF, Vancouver, British Columbia, Canada
| | - L M Golino
- Department of Physics, Faculty of Science and Engineering, Swansea University, Swansea, UK
| | - M B Gomes Gonçalves
- Department of Physics, Faculty of Science and Engineering, Swansea University, Swansea, UK
| | | | - P Granum
- Department of Physics and Astronomy, Aarhus University, Aarhus, Denmark
| | - J S Hangst
- Department of Physics and Astronomy, Aarhus University, Aarhus, Denmark.
| | - M E Hayden
- Department of Physics, Simon Fraser University, Burnaby, British Columbia, Canada
| | - D Hodgkinson
- School of Physics and Astronomy, University of Manchester, Manchester, UK
- Department of Physics, University of California at Berkeley, Berkeley, CA, USA
| | - E D Hunter
- Department of Physics, University of California at Berkeley, Berkeley, CA, USA
| | - C A Isaac
- Department of Physics, Faculty of Science and Engineering, Swansea University, Swansea, UK
| | | | - M A Johnson
- School of Physics and Astronomy, University of Manchester, Manchester, UK
- Cockcroft Institute, Sci-Tech Daresbury, Warrington, UK
| | - J M Jones
- Department of Physics, Faculty of Science and Engineering, Swansea University, Swansea, UK
| | - S A Jones
- Van Swinderen Institute for Particle Physics and Gravity, University of Groningen, Groningen, The Netherlands
| | - S Jonsell
- Department of Physics, Stockholm University, Stockholm, Sweden
| | - A Khramov
- TRIUMF, Vancouver, British Columbia, Canada
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia, Canada
- Department of Physics, British Columbia Institute of Technology, Burnaby, British Columbia, Canada
| | - N Madsen
- Department of Physics, Faculty of Science and Engineering, Swansea University, Swansea, UK
| | - L Martin
- TRIUMF, Vancouver, British Columbia, Canada
| | | | - D Maxwell
- Department of Physics, Faculty of Science and Engineering, Swansea University, Swansea, UK
| | - J T K McKenna
- Department of Physics and Astronomy, Aarhus University, Aarhus, Denmark
- School of Physics and Astronomy, University of Manchester, Manchester, UK
| | - S Menary
- Department of Physics and Astronomy, York University, Toronto, Ontario, Canada
| | - T Momose
- TRIUMF, Vancouver, British Columbia, Canada
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia, Canada
- Department of Chemistry, University of British Columbia, Vancouver, British Columbia, Canada
| | - M Mostamand
- TRIUMF, Vancouver, British Columbia, Canada
- Department of Chemistry, University of British Columbia, Vancouver, British Columbia, Canada
| | - P S Mullan
- Department of Physics, Faculty of Science and Engineering, Swansea University, Swansea, UK
- Institute for Particle Physics and Astrophysics, ETH, Zurich, Switzerland
| | - J Nauta
- Department of Physics, Faculty of Science and Engineering, Swansea University, Swansea, UK
| | | | - A N Oliveira
- Department of Physics and Astronomy, Aarhus University, Aarhus, Denmark
| | - J Peszka
- Department of Physics, Faculty of Science and Engineering, Swansea University, Swansea, UK
- Institute for Particle Physics and Astrophysics, ETH, Zurich, Switzerland
| | - A Powell
- Department of Physics and Astronomy, University of Calgary, Calgary, Alberta, Canada
| | - C Ø Rasmussen
- Experimental Physics Department, CERN, Geneva, Switzerland
| | - F Robicheaux
- Department of Physics and Astronomy, Purdue University, West Lafayette, IN, USA
| | - R L Sacramento
- Instituto de Fisica, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - M Sameed
- School of Physics and Astronomy, University of Manchester, Manchester, UK
- Accelerator Systems Department, CERN, Geneva, Switzerland
| | - E Sarid
- Soreq NRC, Yavne, Israel
- Department of Physics, Ben Gurion University, Beer Sheva, Israel
| | - J Schoonwater
- Department of Physics, Faculty of Science and Engineering, Swansea University, Swansea, UK
| | - D M Silveira
- Instituto de Fisica, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - J Singh
- School of Physics and Astronomy, University of Manchester, Manchester, UK
| | - G Smith
- TRIUMF, Vancouver, British Columbia, Canada
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia, Canada
| | - C So
- TRIUMF, Vancouver, British Columbia, Canada
| | | | - G Stutter
- Department of Physics and Astronomy, Aarhus University, Aarhus, Denmark
- School of Mathematical and Physical Sciences, University of Sussex, Brighton, UK
| | - T D Tharp
- Physics Department, Marquette University, Milwaukee, WI, USA
| | - K A Thompson
- Department of Physics, Faculty of Science and Engineering, Swansea University, Swansea, UK
| | - R I Thompson
- TRIUMF, Vancouver, British Columbia, Canada
- Department of Physics and Astronomy, University of Calgary, Calgary, Alberta, Canada
| | - E Thorpe-Woods
- Department of Physics, Faculty of Science and Engineering, Swansea University, Swansea, UK
| | - C Torkzaban
- Department of Physics, University of California at Berkeley, Berkeley, CA, USA
| | - M Urioni
- University of Brescia, Brescia and INFN Pavia, Pavia, Italy
| | - P Woosaree
- Department of Physics and Astronomy, University of Calgary, Calgary, Alberta, Canada
| | - J S Wurtele
- Department of Physics, University of California at Berkeley, Berkeley, CA, USA
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2
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Antimatter Free-Fall Experiments and Charge Asymmetry. Symmetry (Basel) 2021. [DOI: 10.3390/sym13071192] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
We propose a method by which one could use modified antimatter gravity experiments in order to perform a high-precision test of antimatter charge neutrality. The proposal is based on the application of a strong, external, vertically oriented electric field during an antimatter free-fall gravity experiment in the gravitational field of the Earth. The proposed experimental setup has the potential to drastically improve the limits on the charge-asymmetry parameter ϵ¯q of antimatter. On the theoretical side, we analyze possibilities to describe a putative charge-asymmetry of matter and antimatter, proportional to the parameters ϵq and ϵ¯q, by Lagrangian methods. We found that such an asymmetry could be described by four-dimensional Lorentz-invariant operators that break CPT without destroying the locality of the field theory. The mechanism involves an interaction Lagrangian with field operators decomposed into particle or antiparticle field contributions. Our Lagrangian is otherwise Lorentz, as well as PT invariant. Constraints to be derived on the parameter ϵ¯q do not depend on the assumed theoretical model.
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3
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Baker CJ, Bertsche W, Capra A, Carruth C, Cesar CL, Charlton M, Christensen A, Collister R, Mathad AC, Eriksson S, Evans A, Evetts N, Fajans J, Friesen T, Fujiwara MC, Gill DR, Grandemange P, Granum P, Hangst JS, Hardy WN, Hayden ME, Hodgkinson D, Hunter E, Isaac CA, Johnson MA, Jones JM, Jones SA, Jonsell S, Khramov A, Knapp P, Kurchaninov L, Madsen N, Maxwell D, McKenna JTK, Menary S, Michan JM, Momose T, Mullan PS, Munich JJ, Olchanski K, Olin A, Peszka J, Powell A, Pusa P, Rasmussen CØ, Robicheaux F, Sacramento RL, Sameed M, Sarid E, Silveira DM, Starko DM, So C, Stutter G, Tharp TD, Thibeault A, Thompson RI, van der Werf DP, Wurtele JS. Laser cooling of antihydrogen atoms. Nature 2021; 592:35-42. [PMID: 33790445 PMCID: PMC8012212 DOI: 10.1038/s41586-021-03289-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Accepted: 01/26/2021] [Indexed: 11/08/2022]
Abstract
The photon-the quantum excitation of the electromagnetic field-is massless but carries momentum. A photon can therefore exert a force on an object upon collision1. Slowing the translational motion of atoms and ions by application of such a force2,3, known as laser cooling, was first demonstrated 40 years ago4,5. It revolutionized atomic physics over the following decades6-8, and it is now a workhorse in many fields, including studies on quantum degenerate gases, quantum information, atomic clocks and tests of fundamental physics. However, this technique has not yet been applied to antimatter. Here we demonstrate laser cooling of antihydrogen9, the antimatter atom consisting of an antiproton and a positron. By exciting the 1S-2P transition in antihydrogen with pulsed, narrow-linewidth, Lyman-α laser radiation10,11, we Doppler-cool a sample of magnetically trapped antihydrogen. Although we apply laser cooling in only one dimension, the trap couples the longitudinal and transverse motions of the anti-atoms, leading to cooling in all three dimensions. We observe a reduction in the median transverse energy by more than an order of magnitude-with a substantial fraction of the anti-atoms attaining submicroelectronvolt transverse kinetic energies. We also report the observation of the laser-driven 1S-2S transition in samples of laser-cooled antihydrogen atoms. The observed spectral line is approximately four times narrower than that obtained without laser cooling. The demonstration of laser cooling and its immediate application has far-reaching implications for antimatter studies. A more localized, denser and colder sample of antihydrogen will drastically improve spectroscopic11-13 and gravitational14 studies of antihydrogen in ongoing experiments. Furthermore, the demonstrated ability to manipulate the motion of antimatter atoms by laser light will potentially provide ground-breaking opportunities for future experiments, such as anti-atomic fountains, anti-atom interferometry and the creation of antimatter molecules.
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Affiliation(s)
- C J Baker
- Department of Physics, College of Science, Swansea University, Swansea, UK
| | - W Bertsche
- School of Physics and Astronomy, University of Manchester, Manchester, UK
- Cockcroft Institute, Sci-Tech Daresbury, Warrington, UK
| | - A Capra
- TRIUMF, Vancouver, British Columbia, Canada
| | - C Carruth
- Department of Physics, University of California at Berkeley, Berkeley, CA, USA
| | - C L Cesar
- Instituto de Fisica, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - M Charlton
- Department of Physics, College of Science, Swansea University, Swansea, UK
| | - A Christensen
- Department of Physics, University of California at Berkeley, Berkeley, CA, USA
| | | | - A Cridland Mathad
- Department of Physics, College of Science, Swansea University, Swansea, UK
| | - S Eriksson
- Department of Physics, College of Science, Swansea University, Swansea, UK
| | - A Evans
- Department of Physics and Astronomy, University of Calgary, Calgary, Alberta, Canada
| | - N Evetts
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia, Canada
| | - J Fajans
- Department of Physics, University of California at Berkeley, Berkeley, CA, USA
| | - T Friesen
- Department of Physics and Astronomy, University of Calgary, Calgary, Alberta, Canada
| | | | - D R Gill
- TRIUMF, Vancouver, British Columbia, Canada
| | - P Grandemange
- TRIUMF, Vancouver, British Columbia, Canada
- Department of Physics and Astronomy, University of Calgary, Calgary, Alberta, Canada
| | - P Granum
- Department of Physics and Astronomy, Aarhus University, Aarhus, Denmark
| | - J S Hangst
- Department of Physics and Astronomy, Aarhus University, Aarhus, Denmark.
| | - W N Hardy
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia, Canada
| | - M E Hayden
- Department of Physics, Simon Fraser University, Burnaby, British Columbia, Canada
| | - D Hodgkinson
- School of Physics and Astronomy, University of Manchester, Manchester, UK
| | - E Hunter
- Department of Physics, University of California at Berkeley, Berkeley, CA, USA
| | - C A Isaac
- Department of Physics, College of Science, Swansea University, Swansea, UK
| | - M A Johnson
- School of Physics and Astronomy, University of Manchester, Manchester, UK
- Cockcroft Institute, Sci-Tech Daresbury, Warrington, UK
| | - J M Jones
- Department of Physics, College of Science, Swansea University, Swansea, UK
| | - S A Jones
- Department of Physics and Astronomy, Aarhus University, Aarhus, Denmark
| | - S Jonsell
- Department of Physics, Stockholm University, Stockholm, Sweden
| | - A Khramov
- TRIUMF, Vancouver, British Columbia, Canada
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia, Canada
- Department of Physics, British Columbia Institute of Technology, Burnaby, British Columbia, Canada
| | - P Knapp
- Department of Physics, College of Science, Swansea University, Swansea, UK
| | | | - N Madsen
- Department of Physics, College of Science, Swansea University, Swansea, UK
| | - D Maxwell
- Department of Physics, College of Science, Swansea University, Swansea, UK
| | - J T K McKenna
- TRIUMF, Vancouver, British Columbia, Canada
- Department of Physics and Astronomy, Aarhus University, Aarhus, Denmark
| | - S Menary
- Department of Physics and Astronomy, York University, Toronto, Ontario, Canada
| | - J M Michan
- TRIUMF, Vancouver, British Columbia, Canada
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia, Canada
| | - T Momose
- TRIUMF, Vancouver, British Columbia, Canada.
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia, Canada.
- Department of Chemistry, University of British Columbia, Vancouver, British Columbia, Canada.
| | - P S Mullan
- Department of Physics, College of Science, Swansea University, Swansea, UK
| | - J J Munich
- Department of Physics, Simon Fraser University, Burnaby, British Columbia, Canada
| | | | - A Olin
- TRIUMF, Vancouver, British Columbia, Canada
- Department of Physics and Astronomy, University of Victoria, Victoria, British Columbia, Canada
| | - J Peszka
- Department of Physics, College of Science, Swansea University, Swansea, UK
| | - A Powell
- Department of Physics, College of Science, Swansea University, Swansea, UK
- Department of Physics and Astronomy, University of Calgary, Calgary, Alberta, Canada
| | - P Pusa
- Department of Physics, University of Liverpool, Liverpool, UK
| | - C Ø Rasmussen
- Experimental Physics Department, CERN, Geneva, Switzerland
| | - F Robicheaux
- Department of Physics and Astronomy, Purdue University, West Lafayette, IN, USA
| | - R L Sacramento
- Instituto de Fisica, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - M Sameed
- School of Physics and Astronomy, University of Manchester, Manchester, UK
| | - E Sarid
- Soreq NRC, Yavne, Israel
- Department of Physics, Ben Gurion University, Beer Sheva, Israel
| | - D M Silveira
- TRIUMF, Vancouver, British Columbia, Canada
- Instituto de Fisica, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - D M Starko
- Department of Physics and Astronomy, York University, Toronto, Ontario, Canada
| | - C So
- TRIUMF, Vancouver, British Columbia, Canada
| | - G Stutter
- Department of Physics and Astronomy, Aarhus University, Aarhus, Denmark
| | - T D Tharp
- Physics Department, Marquette University, Milwaukee, WI, USA
| | - A Thibeault
- TRIUMF, Vancouver, British Columbia, Canada
- Faculté de Génie, Université de Sherbrooke, Sherbrooke, Quebec, Canada
| | - R I Thompson
- TRIUMF, Vancouver, British Columbia, Canada
- Department of Physics and Astronomy, University of Calgary, Calgary, Alberta, Canada
| | - D P van der Werf
- Department of Physics, College of Science, Swansea University, Swansea, UK
| | - J S Wurtele
- Department of Physics, University of California at Berkeley, Berkeley, CA, USA
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4
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YAMAZAKI Y. Cold and stable antimatter for fundamental physics. PROCEEDINGS OF THE JAPAN ACADEMY. SERIES B, PHYSICAL AND BIOLOGICAL SCIENCES 2020; 96:471-501. [PMID: 33390386 PMCID: PMC7859084 DOI: 10.2183/pjab.96.034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/16/2020] [Accepted: 10/07/2020] [Indexed: 06/12/2023]
Abstract
The field of cold antimatter physics has rapidly developed in the last 20 years, overlapping with the period of the Antiproton Decelerator (AD) at CERN. The central subjects are CPT symmetry tests and Weak Equivalence Principle (WEP) tests. Various groundbreaking techniques have been developed and are still in progress such as to cool antiprotons and positrons down to extremely low temperature, to manipulate antihydrogen atoms, to construct extremely high-precision Penning traps, etc. The precisions of the antiproton and proton magnetic moments have improved by six orders of magnitude, and also laser spectroscopy of antihydrogen has been realized and reached a relative precision of 2 × 10-12 during the AD time. Antiprotonic helium laser spectroscopy, which started during the Low Energy Antiproton Ring (LEAR) time, has reached a relative precision of 8 × 10-10. Three collaborations joined the WEP tests inventing various unique approaches. An additional new post-decelerator, Extra Low ENergy Antiproton ring (ELENA), has been constructed and will be ready in 2021, which will provide 10-100 times more cold antiprotons to each experiment. A new era of the cold antimatter physics will emerge soon including the transport of antiprotons to other facilities.
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5
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Ahmadi M, Alves BXR, Baker CJ, Bertsche W, Capra A, Carruth C, Cesar CL, Charlton M, Cohen S, Collister R, Eriksson S, Evans A, Evetts N, Fajans J, Friesen T, Fujiwara MC, Gill DR, Hangst JS, Hardy WN, Hayden ME, Isaac CA, Johnson MA, Jones JM, Jones SA, Jonsell S, Khramov A, Knapp P, Kurchaninov L, Madsen N, Maxwell D, McKenna JTK, Menary S, Momose T, Munich JJ, Olchanski K, Olin A, Pusa P, Rasmussen CØ, Robicheaux F, Sacramento RL, Sameed M, Sarid E, Silveira DM, Stutter G, So C, Tharp TD, Thompson RI, van der Werf DP, Wurtele JS. Characterization of the 1S-2S transition in antihydrogen. Nature 2018; 557:71-75. [PMID: 29618820 PMCID: PMC6784861 DOI: 10.1038/s41586-018-0017-2] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2017] [Accepted: 03/06/2018] [Indexed: 11/09/2022]
Abstract
In 1928, Dirac published an equation 1 that combined quantum mechanics and special relativity. Negative-energy solutions to this equation, rather than being unphysical as initially thought, represented a class of hitherto unobserved and unimagined particles-antimatter. The existence of particles of antimatter was confirmed with the discovery of the positron 2 (or anti-electron) by Anderson in 1932, but it is still unknown why matter, rather than antimatter, survived after the Big Bang. As a result, experimental studies of antimatter3-7, including tests of fundamental symmetries such as charge-parity and charge-parity-time, and searches for evidence of primordial antimatter, such as antihelium nuclei, have high priority in contemporary physics research. The fundamental role of the hydrogen atom in the evolution of the Universe and in the historical development of our understanding of quantum physics makes its antimatter counterpart-the antihydrogen atom-of particular interest. Current standard-model physics requires that hydrogen and antihydrogen have the same energy levels and spectral lines. The laser-driven 1S-2S transition was recently observed 8 in antihydrogen. Here we characterize one of the hyperfine components of this transition using magnetically trapped atoms of antihydrogen and compare it to model calculations for hydrogen in our apparatus. We find that the shape of the spectral line agrees very well with that expected for hydrogen and that the resonance frequency agrees with that in hydrogen to about 5 kilohertz out of 2.5 × 1015 hertz. This is consistent with charge-parity-time invariance at a relative precision of 2 × 10-12-two orders of magnitude more precise than the previous determination 8 -corresponding to an absolute energy sensitivity of 2 × 10-20 GeV.
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Affiliation(s)
- M Ahmadi
- Department of Physics, University of Liverpool, Liverpool, UK
| | - B X R Alves
- Department of Physics and Astronomy, Aarhus University, Aarhus, Denmark
| | - C J Baker
- Department of Physics, College of Science, Swansea University, Swansea, UK
| | - W Bertsche
- School of Physics and Astronomy, University of Manchester, Manchester, UK
- Cockcroft Institute, Sci-Tech Daresbury, Warrington, UK
| | - A Capra
- TRIUMF, 4004 Wesbrook Mall, Vancouver, British Columbia, Canada
| | - C Carruth
- Department of Physics, University of California at Berkeley, Berkeley, CA, USA
| | - C L Cesar
- Instituto de Fisica, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - M Charlton
- Department of Physics, College of Science, Swansea University, Swansea, UK
| | - S Cohen
- Department of Physics, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - R Collister
- TRIUMF, 4004 Wesbrook Mall, Vancouver, British Columbia, Canada
| | - S Eriksson
- Department of Physics, College of Science, Swansea University, Swansea, UK
| | - A Evans
- Department of Physics and Astronomy, University of Calgary, Calgary, Alberta, Canada
| | - N Evetts
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia, Canada
| | - J Fajans
- Department of Physics, University of California at Berkeley, Berkeley, CA, USA
| | - T Friesen
- Department of Physics and Astronomy, Aarhus University, Aarhus, Denmark
| | - M C Fujiwara
- TRIUMF, 4004 Wesbrook Mall, Vancouver, British Columbia, Canada
| | - D R Gill
- TRIUMF, 4004 Wesbrook Mall, Vancouver, British Columbia, Canada
| | - J S Hangst
- Department of Physics and Astronomy, Aarhus University, Aarhus, Denmark.
| | - W N Hardy
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia, Canada
| | - M E Hayden
- Department of Physics, Simon Fraser University, Burnaby, British Columbia, Canada
| | - C A Isaac
- Department of Physics, College of Science, Swansea University, Swansea, UK
| | - M A Johnson
- School of Physics and Astronomy, University of Manchester, Manchester, UK
- Cockcroft Institute, Sci-Tech Daresbury, Warrington, UK
| | - J M Jones
- Department of Physics, College of Science, Swansea University, Swansea, UK
| | - S A Jones
- Department of Physics and Astronomy, Aarhus University, Aarhus, Denmark
- Department of Physics, College of Science, Swansea University, Swansea, UK
| | - S Jonsell
- Department of Physics, Stockholm University, Stockholm, Sweden
| | - A Khramov
- TRIUMF, 4004 Wesbrook Mall, Vancouver, British Columbia, Canada
| | - P Knapp
- Department of Physics, College of Science, Swansea University, Swansea, UK
| | - L Kurchaninov
- TRIUMF, 4004 Wesbrook Mall, Vancouver, British Columbia, Canada
| | - N Madsen
- Department of Physics, College of Science, Swansea University, Swansea, UK
| | - D Maxwell
- Department of Physics, College of Science, Swansea University, Swansea, UK
| | - J T K McKenna
- TRIUMF, 4004 Wesbrook Mall, Vancouver, British Columbia, Canada
| | - S Menary
- Department of Physics and Astronomy, York University, Toronto, Ontario, Canada
| | - T Momose
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia, Canada
| | - J J Munich
- Department of Physics, Simon Fraser University, Burnaby, British Columbia, Canada
| | - K Olchanski
- TRIUMF, 4004 Wesbrook Mall, Vancouver, British Columbia, Canada
| | - A Olin
- TRIUMF, 4004 Wesbrook Mall, Vancouver, British Columbia, Canada
- Department of Physics and Astronomy, University of Victoria, Victoria, British Columbia, Canada
| | - P Pusa
- Department of Physics, University of Liverpool, Liverpool, UK
| | - C Ø Rasmussen
- Department of Physics and Astronomy, Aarhus University, Aarhus, Denmark
| | - F Robicheaux
- Department of Physics and Astronomy, Purdue University, West Lafayette, IN, USA
| | - R L Sacramento
- Instituto de Fisica, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - M Sameed
- Department of Physics, College of Science, Swansea University, Swansea, UK
- School of Physics and Astronomy, University of Manchester, Manchester, UK
| | | | - D M Silveira
- Instituto de Fisica, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - G Stutter
- Department of Physics and Astronomy, Aarhus University, Aarhus, Denmark
| | - C So
- Department of Physics and Astronomy, University of Calgary, Calgary, Alberta, Canada
| | - T D Tharp
- Physics Department, Marquette University, Milwaukee, WI, USA
| | - R I Thompson
- Department of Physics and Astronomy, University of Calgary, Calgary, Alberta, Canada
| | - D P van der Werf
- Department of Physics, College of Science, Swansea University, Swansea, UK
- IRFU, CEA/Saclay, Gif-sur-Yvette Cedex, France
| | - J S Wurtele
- Department of Physics, University of California at Berkeley, Berkeley, CA, USA
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Eriksson S. Precision measurements on trapped antihydrogen in the ALPHA experiment. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2018; 376:20170268. [PMID: 29459409 PMCID: PMC5829172 DOI: 10.1098/rsta.2017.0268] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 12/01/2017] [Indexed: 06/08/2023]
Abstract
Both the 1S-2S transition and the ground state hyperfine spectrum have been observed in trapped antihydrogen. The former constitutes the first observation of resonant interaction of light with an anti-atom, and the latter is the first detailed measurement of a spectral feature in antihydrogen. Owing to the narrow intrinsic linewidth of the 1S-2S transition and use of two-photon laser excitation, the transition energy can be precisely determined in both hydrogen and antihydrogen, allowing a direct comparison as a test of fundamental symmetry. The result is consistent with CPT invariance at a relative precision of around 2×10-10 This constitutes the most precise measurement of a property of antihydrogen. The hyperfine spectrum of antihydrogen is determined to a relative uncertainty of 4×10-4 The excited state and the hyperfine spectroscopy techniques currently both show sensitivity at the few 100 kHz level on the absolute scale. Here, the most recent work of the ALPHA collaboration on precision spectroscopy of antihydrogen is presented together with an outlook on improving the precision of measurements involving lasers and microwave radiation. Prospects of measuring the Lamb shift and determining the antiproton charge radius in trapped antihydrogen in the ALPHA apparatus are presented. Future perspectives of precision measurements of trapped antihydrogen in the ALPHA apparatus when the ELENA facility becomes available to experiments at CERN are discussed.This article is part of the Theo Murphy meeting issue 'Antiproton physics in the ELENA era'.
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Affiliation(s)
- S Eriksson
- Department of Physics, College of Science, Swansea University, Singleton Park, Swansea SA2 8PP, UK
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Bertsche WA. Prospects for comparison of matter and antimatter gravitation with ALPHA-g. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2018; 376:20170265. [PMID: 29459415 PMCID: PMC5829170 DOI: 10.1098/rsta.2017.0265] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Accepted: 11/24/2017] [Indexed: 06/08/2023]
Abstract
The ALPHA experiment has recently entered an expansion phase of its experimental programme, driven in part by the expected benefits of conducting experiments in the framework of the new AD + ELENA antiproton facility at CERN. With antihydrogen trapping now a routine operation in the ALPHA experiment, the collaboration is leading progress towards precision atomic measurements on trapped antihydrogen atoms, with the first excitation of the 1S-2S transition and the first measurement of the antihydrogen hyperfine spectrum (Ahmadi et al. 2017 Nature541, 506-510 (doi:10.1038/nature21040); Nature548, 66-69 (doi:10.1038/nature23446)). We are building on these successes to extend our physics programme to include a measurement of antimatter gravitation. We plan to expand a proof-of-principle method (Amole et al. 2013 Nat. Commun.4, 1785 (doi:10.1038/ncomms2787)), first demonstrated in the original ALPHA apparatus, and perform a precise measurement of antimatter gravitational acceleration with the aim of achieving a test of the weak equivalence principle at the 1% level. The design of this apparatus has drawn from a growing body of experience on the simulation and verification of antihydrogen orbits confined within magnetic-minimum atom traps. The new experiment, ALPHA-g, will be an additional atom-trapping apparatus located at the ALPHA experiment with the intention of measuring antihydrogen gravitation.This article is part of the Theo Murphy meeting issue 'Antiproton physics in the ELENA era'.
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Affiliation(s)
- W A Bertsche
- University of Manchester, School of Physics and Astronomy, Oxford Road, Manchester M13 9PL, UK
- The Cockcroft Institute, Keckwick Lane, Daresbury, Warrington WA4 4AD, UK
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Diermaier M, Jepsen CB, Kolbinger B, Malbrunot C, Massiczek O, Sauerzopf C, Simon MC, Zmeskal J, Widmann E. In-beam measurement of the hydrogen hyperfine splitting and prospects for antihydrogen spectroscopy. Nat Commun 2017; 8:15749. [PMID: 28604657 PMCID: PMC5472788 DOI: 10.1038/ncomms15749] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2016] [Accepted: 04/24/2017] [Indexed: 11/09/2022] Open
Abstract
Antihydrogen, the lightest atom consisting purely of antimatter, is an ideal laboratory to study the CPT symmetry by comparison with hydrogen. With respect to absolute precision, transitions within the ground-state hyperfine structure (GS-HFS) are most appealing by virtue of their small energy separation. ASACUSA proposed employing a beam of cold antihydrogen atoms in a Rabi-type experiment, to determine the GS-HFS in a field-free region. Here we present a measurement of the zero-field hydrogen GS-HFS using the spectroscopy apparatus of ASACUSA's antihydrogen experiment. The measured value of νHF=1,420,405,748.4(3.4) (1.6) Hz with a relative precision of 2.7 × 10-9 constitutes the most precise determination of this quantity in a beam and verifies the developed spectroscopy methods for the antihydrogen HFS experiment to the p.p.b. level. Together with the recently presented observation of antihydrogen atoms 2.7 m downstream of the production region, the prerequisites for a measurement with antihydrogen are now available within the ASACUSA collaboration.
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Affiliation(s)
- M. Diermaier
- Stefan-Meyer-Institut für Subatomare Physik, Österreichische Akademie der Wissenschaften, Boltzmanngasse 3, Wien 1090, Austria
| | - C. B. Jepsen
- Experimental Physics Department, CERN, Genève 23, CH-1211, Switzerland
| | - B. Kolbinger
- Stefan-Meyer-Institut für Subatomare Physik, Österreichische Akademie der Wissenschaften, Boltzmanngasse 3, Wien 1090, Austria
| | - C. Malbrunot
- Stefan-Meyer-Institut für Subatomare Physik, Österreichische Akademie der Wissenschaften, Boltzmanngasse 3, Wien 1090, Austria
- Experimental Physics Department, CERN, Genève 23, CH-1211, Switzerland
| | - O. Massiczek
- Stefan-Meyer-Institut für Subatomare Physik, Österreichische Akademie der Wissenschaften, Boltzmanngasse 3, Wien 1090, Austria
| | - C. Sauerzopf
- Stefan-Meyer-Institut für Subatomare Physik, Österreichische Akademie der Wissenschaften, Boltzmanngasse 3, Wien 1090, Austria
| | - M. C. Simon
- Stefan-Meyer-Institut für Subatomare Physik, Österreichische Akademie der Wissenschaften, Boltzmanngasse 3, Wien 1090, Austria
| | - J. Zmeskal
- Stefan-Meyer-Institut für Subatomare Physik, Österreichische Akademie der Wissenschaften, Boltzmanngasse 3, Wien 1090, Austria
| | - E. Widmann
- Stefan-Meyer-Institut für Subatomare Physik, Österreichische Akademie der Wissenschaften, Boltzmanngasse 3, Wien 1090, Austria
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Hori M, Aghai-Khozani H, Sótér A, Barna D, Dax A, Hayano R, Kobayashi T, Murakami Y, Todoroki K, Yamada H, Horváth D, Venturelli L. Buffer-gas cooling of antiprotonic helium to 1.5 to 1.7 K, and antiproton-to-electron mass ratio. Science 2017; 354:610-614. [PMID: 27811273 DOI: 10.1126/science.aaf6702] [Citation(s) in RCA: 68] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2016] [Accepted: 10/03/2016] [Indexed: 11/02/2022]
Abstract
Charge, parity, and time reversal (CPT) symmetry implies that a particle and its antiparticle have the same mass. The antiproton-to-electron mass ratio [Formula: see text] can be precisely determined from the single-photon transition frequencies of antiprotonic helium. We measured 13 such frequencies with laser spectroscopy to a fractional precision of 2.5 × 10-9 to 16 × 10-9 About 2 × 109 antiprotonic helium atoms were cooled to temperatures between 1.5 and 1.7 kelvin by using buffer-gas cooling in cryogenic low-pressure helium gas; the narrow thermal distribution led to the observation of sharp spectral lines of small thermal Doppler width. The deviation between the experimental frequencies and the results of three-body quantum electrodynamics calculations was reduced by a factor of 1.4 to 10 compared with previous single-photon experiments. From this, [Formula: see text] was determined as 1836.1526734(15), which agrees with a recent proton-to-electron experimental value within 8 × 10-10.
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Affiliation(s)
- Masaki Hori
- Max-Planck-Institut für Quantenoptik, Hans-Kopfermann-Strasse 1, 85748 Garching, Germany.
| | - Hossein Aghai-Khozani
- Max-Planck-Institut für Quantenoptik, Hans-Kopfermann-Strasse 1, 85748 Garching, Germany
| | - Anna Sótér
- Max-Planck-Institut für Quantenoptik, Hans-Kopfermann-Strasse 1, 85748 Garching, Germany
| | - Daniel Barna
- MTA Wigner Research Centre for Physics, H-1525 Budapest, Hungary
| | - Andreas Dax
- Department of Physics, University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Ryugo Hayano
- Department of Physics, University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Takumi Kobayashi
- Department of Physics, University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Yohei Murakami
- Department of Physics, University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Koichi Todoroki
- Department of Physics, University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Hiroyuki Yamada
- Department of Physics, University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Dezső Horváth
- MTA Wigner Research Centre for Physics, H-1525 Budapest, Hungary.,Institute of Nuclear Research (ATOMKI), H-4001 Debrecen, Hungary
| | - Luca Venturelli
- Dipartimento di Ingegneria dell'Informazione, Università di Brescia, Istituto Nazionale di Fisica Nucleare, I-25133 Brescia, Italy
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Nagahama H, Smorra C, Sellner S, Harrington J, Higuchi T, Borchert MJ, Tanaka T, Besirli M, Mooser A, Schneider G, Blaum K, Matsuda Y, Ospelkaus C, Quint W, Walz J, Yamazaki Y, Ulmer S. Sixfold improved single particle measurement of the magnetic moment of the antiproton. Nat Commun 2017; 8:14084. [PMID: 28098156 PMCID: PMC5253646 DOI: 10.1038/ncomms14084] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2016] [Accepted: 11/28/2016] [Indexed: 11/09/2022] Open
Abstract
Our current understanding of the Universe comes, among others, from particle physics and cosmology. In particle physics an almost perfect symmetry between matter and antimatter exists. On cosmological scales, however, a striking matter/antimatter imbalance is observed. This contradiction inspires comparisons of the fundamental properties of particles and antiparticles with high precision. Here we report on a measurement of the g-factor of the antiproton with a fractional precision of 0.8 parts per million at 95% confidence level. Our value /2=2.7928465(23) outperforms the previous best measurement by a factor of 6. The result is consistent with our proton g-factor measurement gp/2=2.792847350(9), and therefore agrees with the fundamental charge, parity, time (CPT) invariance of the Standard Model of particle physics. Additionally, our result improves coefficients of the standard model extension which discusses the sensitivity of experiments with respect to CPT violation by up to a factor of 20.
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Affiliation(s)
- H. Nagahama
- RIKEN, Ulmer Initiative Research Unit, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
- Graduate School of Arts and Sciences, University of Tokyo, Tokyo 153-8902, Japan
| | - C. Smorra
- RIKEN, Ulmer Initiative Research Unit, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
- CERN, CH-1211 Geneva 23, Switzerland
| | - S. Sellner
- RIKEN, Ulmer Initiative Research Unit, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
| | - J. Harrington
- Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany
| | - T. Higuchi
- RIKEN, Ulmer Initiative Research Unit, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
- Graduate School of Arts and Sciences, University of Tokyo, Tokyo 153-8902, Japan
| | - M. J. Borchert
- Institut für Quantenoptik, Leibniz Universität Hannover, Welfengarten 1, 30167 Hannover, Germany
| | - T. Tanaka
- RIKEN, Ulmer Initiative Research Unit, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
- Graduate School of Arts and Sciences, University of Tokyo, Tokyo 153-8902, Japan
| | - M. Besirli
- RIKEN, Ulmer Initiative Research Unit, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
| | - A. Mooser
- RIKEN, Ulmer Initiative Research Unit, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
| | - G. Schneider
- RIKEN, Ulmer Initiative Research Unit, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
- Institut für Physik, Johannes Gutenberg-Universität, 55099 Mainz, Germany
| | - K. Blaum
- Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany
| | - Y. Matsuda
- Graduate School of Arts and Sciences, University of Tokyo, Tokyo 153-8902, Japan
| | - C. Ospelkaus
- Institut für Quantenoptik, Leibniz Universität Hannover, Welfengarten 1, 30167 Hannover, Germany
- Physikalisch-Technische Bundesanstalt, QUEST, Bundesallee 100, 38116 Braunschweig, Germany
| | - W. Quint
- GSI-Helmholtzzentrum für Schwerionenforschung GmbH, 64291 Darmstadt, Germany
| | - J. Walz
- Institut für Physik, Johannes Gutenberg-Universität, 55099 Mainz, Germany
- Helmholtz-Institut Mainz, sektion MAM, 55099 Mainz, Germany
| | - Y. Yamazaki
- RIKEN, Atomic Physics Research Unit, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
| | - S. Ulmer
- RIKEN, Ulmer Initiative Research Unit, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
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Ahmadi M, Alves BXR, Baker CJ, Bertsche W, Butler E, Capra A, Carruth C, Cesar CL, Charlton M, Cohen S, Collister R, Eriksson S, Evans A, Evetts N, Fajans J, Friesen T, Fujiwara MC, Gill DR, Gutierrez A, Hangst JS, Hardy WN, Hayden ME, Isaac CA, Ishida A, Johnson MA, Jones SA, Jonsell S, Kurchaninov L, Madsen N, Mathers M, Maxwell D, McKenna JTK, Menary S, Michan JM, Momose T, Munich JJ, Nolan P, Olchanski K, Olin A, Pusa P, Rasmussen CØ, Robicheaux F, Sacramento RL, Sameed M, Sarid E, Silveira DM, Stracka S, Stutter G, So C, Tharp TD, Thompson JE, Thompson RI, van der Werf DP, Wurtele JS. Observation of the 1S–2S transition in trapped antihydrogen. Nature 2016; 541:506-510. [DOI: 10.1038/nature21040] [Citation(s) in RCA: 99] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2016] [Accepted: 12/07/2016] [Indexed: 11/09/2022]
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