The ALPHA antihydrogen trapping apparatus

Amole, C.; Andresen, Gorm Bruun; Ashkezari, M. D.; Baquero-Ruiz, M.; Bertsche, W.; Bowe, P. D.; Butler, E.; Capra, A.; Carpenter, Patrick; Cesar, C. L.; Chapman, S.; Charlton, M.; Deller, A.; Eriksson, S.; Escallier, J.; Fajans, J.; Friesen, T.; Fujiwara, M.; Gill, D. R.; Gutiérrez, A.; Hangst, J. S.; Hardy, W. N.; Hayano, R.; Hayden, M. E.; Humphries, A. J.; Hurt, J. L.; Hydomako, R.; Isaac, C. A.; Jenkins, Michael J.; Jonsell, Svante; Jørgensen, L. V.; Kerrigan, Sean; Kurchaninov, L. L.; Madsen, N.; Marone, A.; McKenna, J. T. K.; Menary, S.; Nolan, P.; Olchanski, K.; Olin, Å.; Parker, B.; Povilus, A.; Pusa, P.; Robicheaux, F.; Sarid, E.; Seddon, D.; Nasr, S. Seif El; Silveira, D. M.; So, C.; Storey, J. W.; Thompson, R. I.; Thornhill, J.; Wells, David; Werf, D. P. van der; Wurtele, J. S.; Yamazaki, Y.

doi:10.1016/j.nima.2013.09.043

Cited by 59 publications

(51 citation statements)

References 44 publications

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“…The latter analysis has the same design as used in previous experiments 12,16 . The former analysis is modified to achieve a much lower background, through the addition of more variables that enhance the signal-to-background discrimination.…”

Section: Methodsmentioning

confidence: 99%

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Observation of the hyperfine spectrum of antihydrogen

Ahmadi

Alves

Baker

et al. 2017

Nature

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110

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The observation of hyperfine structure in atomic hydrogen by Rabi and co-workers 1-3 and the measurement 4 of the zero-field groundstate splitting at the level of seven parts in 10 13 are important achievements of mid-twentieth-century physics. The work that led to these achievements also provided the first evidence for the anomalous magnetic moment of the electron 5-8 , inspired Schwinger's relativistic theory of quantum electrodynamics 9,10 and gave rise to the hydrogen maser 11 , which is a critical component of modern navigation, geo-positioning and very-long-baseline interferometry systems. Research at the Antiproton Decelerator at CERN by the ALPHA collaboration extends these enquiries into the antimatter sector. Recently, tools have been developed that enable studies of the hyperfine structure of antihydrogen 12 -the antimatter counterpart of hydrogen. The goal of such studies is to search for any differences that might exist between this archetypal pair of atoms, and thereby to test the fundamental principles on which quantum field theory is constructed. Magnetic trapping of antihydrogen atoms 13,14 provides a means of studying them by combining electromagnetic interaction with detection techniques that are unique to antimatter 12,15 . Here we report the results of a microwave spectroscopy experiment in which we probe the response of antihydrogen over a controlled range of frequencies. The data reveal clear and distinct signatures of two allowed transitions, from which we obtain a direct, magneticfield-independent measurement of the hyperfine splitting. From a set of trials involving 194 detected atoms, we determine a splitting of 1,420.4 ± 0.5 megahertz, consistent with expectations for atomic hydrogen at the level of four parts in 10 4 . This observation of the detailed behaviour of a quantum transition in an atom of antihydrogen exemplifies tests of fundamental symmetries such as charge-parity-time in antimatter, and the techniques developed here will enable more-precise such tests.In an earlier experiment 12 using the original ALPHA apparatus 16 , we demonstrated microwave-induced spin flips in trapped antihydrogen. The current work was carried out using the second-generation ALPHA-2 device (Fig.

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Section: Methodsmentioning

confidence: 99%

“…In an earlier experiment 12 using the original ALPHA apparatus 16 , we demonstrated microwave-induced spin flips in trapped antihydrogen. The current work was carried out using the second-generation ALPHA-2 device (Fig.…”

mentioning

confidence: 94%

Observation of the hyperfine spectrum of antihydrogen

Ahmadi

Alves

Baker

et al. 2017

Nature

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110

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“…[4]. H confinement is achieved by a threedimensional magnetic field minimum at the centre of the Penning trap.…”

Section: Apparatusmentioning

confidence: 99%

Untitled

Olin¹

2017

Exa 2014

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This paper discusses the first observation of stimulated magnetic resonance transitions between the hyperfine levels of trapped ground state atomic antihydrogen, confirming its presence in the ALPHA apparatus. Our observations show that these transitions are consistent with the values in hydrogen to within 4 parts in 10 3 . Simulations of the trapped antiatoms in a microwave field are consistent with our measurements. IntroductionThe combination of charge conjugation, parity, and time reversal, CPT is understood to be a required symmetry of relativistic quantum field theories [1,2]. CPT violation has not been observed. Precision comparisons of atomic systems of matter and antimatter directly test the extent to which this symmetry is satisfied since CPT predicts the equality of their energy levels. Antihydrogen (H), the bound state of an antiproton and a positron is the simplest stable antimatter atomic system; its matter analogue, the hydrogen atom, is the best measured atomic system in modern physics. The hydrogen ground state hyperfine interval at 1420MHz has been measured to a precision of 2 mHz. A precise measurement of this quantity in antihydrogen would be sensitive to a ALPHA collaboration http://alpha.web.cern.ch; C. Amole, M

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“…The primary mechanism for antihydrogen production in the ALPHA experiment is a three-body scattering process that relies on a high-density positron plasma [35]. More than 10 6 positrons are trapped with a density of > 10 7ē /cm 3 [10].…”

Section: Charge Densitymentioning

confidence: 99%

“…The resulting antiatoms are typically created with energy above the magnetic trap depth, and most antiatoms are lost during recombination. Typical yields in the ALPHA apparatus are several trapped antiatoms per attempt every ≈15 minutes [10,11]. The ASACUSA experiment has pursued an alternative to spectroscopy on trapped atoms with a CUSP trap [12], which uses an anti-Helmholtz field to generate a beam of spin polarized antihydrogen for eventual microwave spectroscopy atoms [13,14].…”

Section: Introductionmentioning

confidence: 99%

Investigation of two-frequency Paul traps for antihydrogen production

et al. 2016

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Radio-frequency (rf) Paul traps operated with multifrequency rf trapping potentials provide the ability to independently confine charged particle species with widely different charge-to-mass ratios. In particular, these traps may find use in the field of antihydrogen recombination, allowing antiproton and positron clouds to be trapped and confined in the same volume without the use of large superconducting magnets. We explore the stability regions of two-frequency Paul traps and perform numerical simulations of small samples of multispecies charged-particle mixtures of up to twelve particles that indicate the promise of these traps for antihydrogen recombination.

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The ALPHA antihydrogen trapping apparatus

Cited by 59 publications

References 44 publications

Observation of the hyperfine spectrum of antihydrogen

Observation of the hyperfine spectrum of antihydrogen

Untitled

Investigation of two-frequency Paul traps for antihydrogen production

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