Buffer-gas cooling of antiprotonic helium to 1.5 to 1.7 K, and antiproton-to–electron mass ratio

Hori, Masaki; Aghai-Khozani, Hossein; Sótér, Anna; Barna, D.; Dax, A.; Hayano, R.; Kobayashi, Takeyuki; Murakami, Yo; Todoroki, K.; Yamada, Hiroyuki; Horváth, D.; Venturelli, L.

doi:10.1126/science.aaf6702

Cited by 104 publications

(86 citation statements)

References 41 publications

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“…The greatly improved trapping rate demonstrated here bodes well for many other future antihydrogen experiments, including microwave hyperfine transitions, spectroscopy and laser cooling using Lyman-α light 21 , and gravitational studies with neutral antimatter. The current result, along with recently determined limits on the antiproton-electron mass ratio 22 and antiproton charge-to-mass ratio 23 , demonstrate that tests of fundamental symmetries with antimatter are maturing rapidly.…”

mentioning

confidence: 55%

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

Ahmadi

Alves

Baker

et al. 2016

Nature

130

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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mentioning

confidence: 55%

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

Ahmadi

Alves

Baker

et al. 2016

Nature

130

140

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“…In the later of the two studies a stochastic acceleration technique was used to find that the putative charge was less 0.71 parts per billion in units of e. When assuming charge superposition and the best available determination of thep charge with respect to the proton of equality to within 5 × 10 −10 , this could be used to set similar limits on the electron/positron charge ratio [31].…”

Section: Selected Experimental Resultsmentioning

confidence: 99%

Closing in on the properties of antihydrogen

Charlton

2017

Eur. Phys. J. D

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Abstract. Recent achievements leading, amongst other things, to the observation of the two-photon 1S-2S transition in antihydrogen are reviewed. We summarise some of the technical advances that were necessary to facilitate this, and how these addressed the requirements posed by the underlying physical processes. Aspects of the latter have been elucidated by simulations aimed at describing as closely as possible the experimental situations, and we describe some recent insights from that work. We will close with a look to the future.

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“…The measurement has been performed at AD [25][26][27][28][29] which is presently the only existing source of slow antiprotons. Theps delivered by AD have a momentum p = 100 MeV/c (corresponding to an energy of 5.3 MeV) with a spread of ∆p/p = 0.01% and an emittance of (2-3)π mm mrad.…”

Section: Experimental Methods and Apparatusmentioning

confidence: 99%

Antiproton-nucleus annihilation cross section at low energy

et al. 2018

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Abstract. The antinucleon-nuclei annihilation cross sections at low energies were systematically measured at CERN in the 80's and 90's with the LEAR facility and later with the Antiproton Decelerator. Unfortunately only few data exist for very low energy antiprotons (p<500 MeV/c) on medium and heavy nuclei. A deeper knowledge is required by fundamental physics and can have consequence also in cosmology and medical physics. In order to fill the gap, the ASACUSA Collaboration has very recently measured the annihilation cross section of 100 MeV/c antiprotons on carbon. In the present work the experimental result is presented together with a comparison both with the antineutron data on the same target at the same energies and with the other existing antiproton data at higher energies.

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Buffer-gas cooling of antiprotonic helium to 1.5 to 1.7 K, and antiproton-to–electron mass ratio

Cited by 104 publications

References 41 publications

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

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

Closing in on the properties of antihydrogen

Antiproton-nucleus annihilation cross section at low energy

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