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1. Design and Performance of a Novel Low Energy Multi-Species Beamline for the ALPHA Antihydrogen Experiment

Author

Baker, C. J., Bertsche, W., Capra, A., Cesar, C. L., Charlton, M., Christensen, A. J., Collister, R., Mathad, A. Cridland, Eriksson, S., Evans, A., Evetts, N., Fabbri, S., Fajans, J., Friesen, T., Fujiwara, M. C., Gill, D. R., Grandemange, P., Granum, P., Hangst, J. S., Hayden, M. E., Hodgkinson, D., Isaac, C. A., Johnson, M. A., Jones, J. M., Jones, S. A., Khramov, A., Kurchaninov, L., Madsen, N., Maxwell, D., McKenna, J. T. K., Menary, S., Momose, T., Mullan, P. S., Munich, J. J., Olchanski, K., Peszka, J., Powell, A., Rasmussen, C. O., Sacramento, R. L., Sameed, M., Sarid, E., Silveira, D. M., So, C., Starko, D. M., Stutter, G., Tharp, T. D., Thompson, R. I., Torkzaban, C., van der Werf, D. P., and Wurtele, J. S.

Subjects
Physics - Accelerator Physics
Abstract

The ALPHA Collaboration, based at the CERN Antiproton Decelerator, has recently implemented a novel beamline for low-energy ($\lesssim$ 100 eV) positron and antiproton transport between cylindrical Penning traps that have strong axial magnetic fields. Here, we describe how a combination of semianalytical and numerical calculations were used to optimise the layout and design of this beamline. Using experimental measurements taken during the initial commissioning of the instrument, we evaluate its performance and validate the models used for its development. By combining data from a range of sources, we show that the beamline has a high transfer efficiency, and estimate that the percentage of particles captured in the experiments from each bunch is (78 $\pm$ 3)% for up to $10^{5}$ antiprotons, and (71 $\pm$ 5)% for bunches of up to $10^{7}$ positrons., Comment: 15 pages, 15 figures

Published
2022
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2. Observation of the effect of gravity on the motion of antimatter

Author

Anderson, E. K., Baker, C. J., Bertsche, W., Bhatt, N. M., Bonomi, G., Capra, A., Carli, I., Cesar, C. L., 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, M. C., Gill, D. R., Golino, L. M., Gomes Gonçalves, M. B., Grandemange, P., Granum, P., Hangst, J. S., Hayden, M. E., Hodgkinson, D., Hunter, E. D., Isaac, C. A., Jimenez, A. J. U., Johnson, M. A., Jones, J. M., Jones, S. A., Jonsell, S., Khramov, A., Madsen, N., Martin, L., Massacret, N., Maxwell, D., McKenna, J. T. K., Menary, S., Momose, T., Mostamand, M., Mullan, P. S., Nauta, J., Olchanski, K., Oliveira, A. N., Peszka, J., Powell, A., Rasmussen, C. Ø., Robicheaux, F., Sacramento, R. L., Sameed, M., Sarid, E., Schoonwater, J., Silveira, D. M., Singh, J., Smith, G., So, C., Stracka, S., Stutter, G., Tharp, T. D., Thompson, K. A., Thompson, R. I., Thorpe-Woods, E., Torkzaban, C., Urioni, M., Woosaree, P., and Wurtele, J. S.

Published
2023
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4. Laser cooling of antihydrogen atoms

Author

Baker, C. J., Bertsche, W., Capra, A., Carruth, C., Cesar, C. L., Charlton, M., Christensen, A., Collister, R., Mathad, A. Cridland, Eriksson, S., Evans, A., Evetts, N., Fajans, J., Friesen, T., Fujiwara, M. C., Gill, D. R., Grandemange, P., Granum, P., Hangst, J. S., Hardy, W. N., Hayden, M. E., Hodgkinson, D., Hunter, E., Isaac, C. A., Johnson, M. A., Jones, J. M., Jones, S. A., Jonsell, S., Khramov, A., Knapp, P., Kurchaninov, L., Madsen, N., Maxwell, D., McKenna, J. T. K., Menary, S., Michan, J. M., Momose, T., Mullan, P. S., Munich, J. J., Olchanski, K., Olin, A., Peszka, J., Powell, A., Pusa, P., Rasmussen, C. Ø., Robicheaux, F., Sacramento, R. L., Sameed, M., Sarid, E., Silveira, D. M., Starko, D. M., So, C., Stutter, G., Tharp, T. D., Thibeault, A., Thompson, R. I., van der Werf, D. P., and Wurtele, J. S.

Published
2021
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5. Sympathetic cooling of positrons to cryogenic temperatures for antihydrogen production

Author

Baker, C. J., Bertsche, W., Capra, A., Cesar, C. L., Charlton, M., Mathad, A. Cridland, Eriksson, S., Evans, A., Evetts, N., Fabbri, S., Fajans, J., Friesen, T., Fujiwara, M. C., Grandemange, P., Granum, P., Hangst, J. S., Hayden, M. E., Hodgkinson, D., Isaac, C. A., Johnson, M. A., Jones, J. M., Jones, S. A., Jonsell, S., Kurchaninov, L., Madsen, N., Maxwell, D., McKenna, J. T. K., Menary, S., Momose, T., Mullan, P., Olchanski, K., Olin, A., Peszka, J., Powell, A., Pusa, P., Rasmussen, C. Ø., Robicheaux, F., Sacramento, R. L., Sameed, M., Sarid, E., Silveira, D. M., Stutter, G., So, C., Tharp, T. D., Thompson, R. I., van der Werf, D. P., and Wurtele, J. S.

Published
2021
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6. Antiproton cloud compression in the ALPHA apparatus at CERN

Author

Gutierrez, A., Ashkezari, M. D., Baquero-Ruiz, M., Bertsche, W., Burrows, C., Butler, E., Capra, A., Cesar, C. L., Charlton, M., Dunlop, R., Eriksson, S., Evetts, N., Fajans, J., Friesen, T., Fujiwara, M. C., Gill, D. R., Hangst, J. S., Hardy, W. N., Hayden, M. E., Isaac, C. A., Jonsell, S., Kurchaninov, L., Little, A., Madsen, N., McKenna, J. T. K., Menary, S., Napoli, S. C., Nolan, P., Olchanski, K., Olin, A., Pusa, P., Rasmussen, C. Ø., Robicheaux, F., Sacramento, R. L., Sarid, E., Silveira, D. M., So, C., Stracka, S., Tarlton, J., Tharp, T. D., Thompson, R. I., Tooley, P., Turner, M., van der Werf, D. P., Wurtele, J. S., Zhmoginov, A. I., Wada, Michiharu, editor, Schury, Peter, editor, and Ichikawa, Yuichi, editor

Published
2017
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7. Observation of the 1S–2P Lyman-α transition in antihydrogen

Author

Ahmadi, M., Alves, B. X. R., Baker, C. J., Bertsche, W., Capra, A., Carruth, C., Cesar, C. L., Charlton, M., Cohen, S., Collister, R., Eriksson, S., Evans, A., Evetts, N., Fajans, J., Friesen, T., Fujiwara, M. C., Gill, D. R., Hangst, J. S., Hardy, W. N., Hayden, M. E., Hunter, E. D., Isaac, C. A., Johnson, M. A., Jones, J. M., Jones, S. A., Jonsell, S., Khramov, A., Knapp, P., Kurchaninov, L., Madsen, N., Maxwell, D., McKenna, J. T. K., Menary, S., Michan, J. M., Momose, T., Munich, J. J., Olchanski, K., Olin, A., Pusa, P., Rasmussen, C. Ø., Robicheaux, F., Sacramento, R. L., Sameed, M., Sarid, E., Silveira, D. M., Starko, D. M., Stutter, G., So, C., Tharp, T. D., Thompson, R. I., van der Werf, D. P., and Wurtele, J. S.

Published
2018
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8. Characterization of the 1S–2S transition in antihydrogen

Author

Ahmadi, M., Alves, B. X. R., Baker, C. J., Bertsche, W., Capra, A., Carruth, C., Cesar, C. L., Charlton, M., Cohen, S., Collister, R., Eriksson, S., Evans, A., Evetts, N., Fajans, J., Friesen, T., Fujiwara, M. C., Gill, D. R., Hangst, J. S., Hardy, W. N., Hayden, M. E., Isaac, C. A., Johnson, M. A., Jones, J. M., Jones, S. A., Jonsell, S., Khramov, A., Knapp, P., Kurchaninov, L., Madsen, N., Maxwell, D., McKenna, J. T. K., Menary, S., Momose, T., Munich, J. J., Olchanski, K., Olin, A., Pusa, P., Rasmussen, C. Ø., Robicheaux, F., Sacramento, R. L., Sameed, M., Sarid, E., Silveira, D. M., Stutter, G., So, C., Tharp, T. D., Thompson, R. I., van der Werf, D. P., and Wurtele, J. S.

Published
2018
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9. Observation of the hyperfine spectrum of antihydrogen

Author

Ahmadi, M., Alves, B. X. R., Baker, C. J., Bertsche, W., Butler, E., Capra, A., Carruth, C., Cesar, C. L., Charlton, M., Cohen, S., Collister, R., Eriksson, S., Evans, A., Evetts, N., Fajans, J., Friesen, T., Fujiwara, M. C., Gill, D. R., Gutierrez, A., Hangst, J. S., Hardy, W. N., Hayden, M. E., Isaac, C. A., Ishida, A., Johnson, M. A., Jones, S. A., Jonsell, S., Kurchaninov, L., Madsen, N., Mathers, M., Maxwell, D., McKenna, J. T. K., Menary, S., Michan, J. M., Momose, T., Munich, J. J., Nolan, P., Olchanski, K., Olin, A., Pusa, P., Rasmussen, C. ., Robicheaux, F., Sacramento, R. L., Sameed, M., Sarid, E., Silveira, D. M., Stracka, S., Stutter, G., So, C., Tharp, T. D., Thompson, J. E., Thompson, R. I., van der Werf, D. P., and Wurtele, J. S.

Subjects
Antimatter -- Observations, Hydrogen -- Observations, Environmental issues, Science and technology, Zoology and wildlife conservation
Abstract

Author(s): M. Ahmadi [1]; B. X. R. Alves [2]; C. J. Baker [3]; W. Bertsche [4, 5]; E. Butler [6]; A. Capra [7]; C. Carruth [8]; C. L. Cesar [9]; [...]

Published
2017
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10. Observation of the 1S2S transition in trapped antihydrogen

Author

Ahmadi, M., Alves, B. X. R., Baker, C. J., Bertsche, W., Butler, E., Capra, A., Carruth, C., Cesar, C. L., Charlton, M., Cohen, S., Collister, R., Eriksson, S., Evans, A., Evetts, N., Fajans, J., Friesen, T., Fujiwara, M. C., Gill, D. R., Gutierrez, A., Hangst, J. S., Hardy, W. N., Hayden, M. E., Isaac, C. A., Ishida, A., Johnson, M. A., Jones, S. A., Jonsell, S., Kurchaninov, L., Madsen, N., Mathers, M., Maxwell, D., McKenna, J. T. K., Menary, S., Michan, J. M., Momose, T., Munich, J. J., Nolan, P., Olchanski, K., Olin, A., Pusa, P., Rasmussen, C. ., Robicheaux, F., Sacramento, R. L., Sameed, M., Sarid, E., Silveira, D. M., Stracka, S., Stutter, G., So, C., Tharp, T. D., Thompson, J. E., Thompson, R. I., van der Werf, D. P., and Wurtele, J. S.

Subjects
Phase transitions (Physics) -- Observations, Antimatter -- Properties, Environmental issues, Science and technology, Zoology and wildlife conservation
Abstract

Author(s): M. Ahmadi [1]; B. X. R. Alves [2]; C. J. Baker [3]; W. Bertsche [4, 5]; E. Butler [6]; A. Capra [7]; C. Carruth [8]; C. L. Cesar [9]; [...]

Published
2017
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11. Observation of the 1S–2S transition in trapped antihydrogen

Author

Ahmadi, M., Alves, B. X. R., Baker, C. J., Bertsche, W., Butler, E., Capra, A., Carruth, C., Cesar, C. L., Charlton, M., Cohen, S., Collister, R., Eriksson, S., Evans, A., Evetts, N., Fajans, J., Friesen, T., Fujiwara, M. C., Gill, D. R., Gutierrez, A., Hangst, J. S., Hardy, W. N., Hayden, M. E., Isaac, C. A., Ishida, A., Johnson, M. A., Jones, S. A., Jonsell, S., Kurchaninov, L., Madsen, N., Mathers, M., Maxwell, D., McKenna, J. T. K., Menary, S., Michan, J. M., Momose, T., Munich, J. J., Nolan, P., Olchanski, K., Olin, A., Pusa, P., Rasmussen, C. Ø., Robicheaux, F., Sacramento, R. L., Sameed, M., Sarid, E., Silveira, D. M., Stracka, S., Stutter, G., So, C., Tharp, T. D., Thompson, J. E., Thompson, R. I., van der Werf, D. P., and Wurtele, J. S.

Published
2017
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12. Antiproton cloud compression in the ALPHA apparatus at CERN

Author

Gutierrez, A., Ashkezari, M. D., Baquero-Ruiz, M., Bertsche, W., Burrows, C., Butler, E., Capra, A., Cesar, C. L., Charlton, M., Dunlop, R., Eriksson, S., Evetts, N., Fajans, J., Friesen, T., Fujiwara, M. C., Gill, D. R., Hangst, J. S., Hardy, W. N., Hayden, M. E., Isaac, C. A., Jonsell, S., Kurchaninov, L., Little, A., Madsen, N., K. McKenna, J. T., Menary, S., Napoli, S. C., Nolan, P., Olchanski, K., Olin, A., Pusa, P., Rasmussen, C. Ø., Robicheaux, F., Sacramento, R. L., Sarid, E., Silveira, D. M., So, C., Stracka, S., Tarlton, J., Tharp, T. D., Thompson, R. I., Tooley, P., Turner, M., van der Werf, D. P., Wurtele, J. S., and Zhmoginov, A. I.

Published
2015
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13. An improved limit on the charge of antihydrogen from stochastic acceleration

Author

Ahmadi, M., Baquero-Ruiz, M., Bertsche, W., Butler, E., Capra, A., Carruth, C., Cesar, C. L., Charlton, M., Charman, A. E., Eriksson, S., Evans, L. T., Evetts, N., Fajans, J., Friesen, T., Fujiwara, M. C., Gill, D. R., Gutierrez, A., Hangst, J. S., Hardy, W. N., Hayden, M. E., Isaac, C. A., Ishida, A., Jones, S. A., Jonsell, S., Kurchaninov, L., Madsen, N., Maxwell, D., McKenna, J. T. K., Menary, S., Michan, J. M., Momose, T., Munich, J. J., Nolan, P., Olchanski, K., Olin, A., 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., van der Werf, D. P., Wurtele, J. S., and Zhmoginov, A. I.

Published
2016
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14. Antiproton cloud compression in the ALPHA apparatus at CERN

Author

Gutierrez, A., primary, Ashkezari, M. D., additional, Baquero-Ruiz, M., additional, Bertsche, W., additional, Burrows, C., additional, Butler, E., additional, Capra, A., additional, Cesar, C. L., additional, Charlton, M., additional, Dunlop, R., additional, Eriksson, S., additional, Evetts, N., additional, Fajans, J., additional, Friesen, T., additional, Fujiwara, M. C., additional, Gill, D. R., additional, Hangst, J. S., additional, Hardy, W. N., additional, Hayden, M. E., additional, Isaac, C. A., additional, Jonsell, S., additional, Kurchaninov, L., additional, Little, A., additional, Madsen, N., additional, McKenna, J. T. K., additional, Menary, S., additional, Napoli, S. C., additional, Nolan, P., additional, Olchanski, K., additional, Olin, A., additional, Pusa, P., additional, Rasmussen, C. Ø., additional, Robicheaux, F., additional, Sacramento, R. L., additional, Sarid, E., additional, Silveira, D. M., additional, So, C., additional, Stracka, S., additional, Tarlton, J., additional, Tharp, T. D., additional, Thompson, R. I., additional, Tooley, P., additional, Turner, M., additional, van der Werf, D. P., additional, Wurtele, J. S., additional, and Zhmoginov, A. I., additional

Published
2015
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15. Erratum: Observation of the hyperfine spectrum of antihydrogen

Author

Ahmadi, M., Alves, B. X. R., Baker, C. J., Bertsche, W., Butler, E., Capra, A., Carruth, C., Cesar, C. L., Charlton, M., Cohen, S., Collister, R., Eriksson, S., Evans, A., Evetts, N., Fajans, J., Friesen, T., Fujiwara, M. C., Gill, D. R., Gutierrez, A., Hangst, J. S., Hardy, W. N., Hayden, M. E., Isaac, C. A., Ishida, A., Johnson, M. A., Jones, S. A., Jonsell, S., Kurchaninov, L., Madsen, N., Mathers, M., Maxwell, D., McKenna, J. T. K., Menary, S., Michan, J. M., Momose, T., Munich, J. J., Nolan, P., Olchanski, K., Olin, A., Pusa, P., Rasmussen, C. ., Robicheaux, F., Sacramento, R. L., Sameed, M., Sarid, E., Silveira, D. M., Stracka, S., Stutter, G., So, C., Tharp, T. D., Thompson, J. E., Thompson, R. I., van der Werf, D. P., and Wurtele, J. S.

Subjects
Environmental issues, Science and technology, Zoology and wildlife conservation
Abstract

Author(s): M. Ahmadi; B. X. R. Alves; C. J. Baker; W. Bertsche; E. Butler; A. Capra; C. Carruth; C. L. Cesar; M. Charlton; S. Cohen; R. Collister; S. Eriksson; A. [...]

Published
2018
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16. Heteronuclear molecules from matrix isolation sublimation and atomic diffusion.

Author

Oliveira, A. N., Sacramento, R. L., Moreira, L. S., Azevedo, L. O. A., Wolff, W., and Lenz Cesar, C.

Subjects
*HETERONUCLEAR diatomic molecules, *TIME-of-flight measurements, *CRYOGENICS, *ATOMS, *ELECTRONS
Abstract

We demonstrate the production of cryogenic beams of heteronuclear molecules from the matrix isolation sublimation (MISu) technique. A sapphire mirror serves as a substrate whereupon a solid Ne matrix is grown. Atoms of Li, H, Ca, and C are implanted into the matrix via subsequent laser ablation of different solid precursors such as Ca, Li, LiH, and graphite. The matrix is sublimated into vacuum generating a cryogenic beam of Ne carrying the previously isolated neutral atomic and molecular species. A compact and low energy electron source and time-of-flight mass spectrometer was designed to fit this system at low temperature. With electron ionization time-of-flight mass spectrometry, we analyze the species coming from MISu and demonstrate the formation of heteronuclear molecules in the matrix. In this first study, we produced LiCa from the sequential implantation of Li and Ca into the matrix and some clusters of CnLim after Li and C ablation. Also from ablation of a single LiH pellet, we observed clusters of LinHm. This novel technique opens up the opportunity to generate cryogenic beams of different molecules for precision physics and chemistry studies. Laser or microwave high resolution spectroscopy of a molecular beam benefits from low translational and rovibrational temperatures and forward velocities, such as the ones produced in this technique. Toward the prospect of enhancing the molecular formation, we introduce a new method to study the atomic diffusion of Li and Ca in the Ne matrix via laser spectroscopy during sublimation. We estimate a small diffusion coefficient at 7 K, but a surprisingly linear atomic dispersion during sublimation. The method is extensive to other species and matrices. [ABSTRACT FROM AUTHOR]

Published
2018
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17. Investigation of the fine structure of antihydrogen

Author

Ahmadi, M., Alves, B. X. R., Baker, C. J., Bertsche, W., Capra, A., Carruth, C., Cesar, C. L., Charlton, M., Cohen, S., Collister, R., Eriksson, S., Evans, A., Evetts, N., Fajans, J., Friesen, T., Fujiwara, M. C., Gill, D. R., Granum, P., Hangst, J. S., Hardy, W. N., Hayden, M. E., Hunter, E. D., Isaac, C. A., Johnson, M. A., Jones, J. M., Jones, S. A., Jonsell, Svante, Khramov, A., Knapp, P., Kurchaninov, L., Madsen, N., Maxwell, D., McKenna, J. T. K., Menary, S., Michan, J. M., Momose, T., Munich, J. J., Olchanski, K., Olin, A., Pusa, P., Rasmussen, C. Ø., Robicheaux, F., Sacramento, R. L., Sameed, M., Sarid, E., Silveira, D. M., So, C., Starko, D. M., Stutter, G., Tharp, T. D., Thompson, R. I., van der Werf, D. P., Wurtele, J. S., Ahmadi, M., Alves, B. X. R., Baker, C. J., Bertsche, W., Capra, A., Carruth, C., Cesar, C. L., Charlton, M., Cohen, S., Collister, R., Eriksson, S., Evans, A., Evetts, N., Fajans, J., Friesen, T., Fujiwara, M. C., Gill, D. R., Granum, P., Hangst, J. S., Hardy, W. N., Hayden, M. E., Hunter, E. D., Isaac, C. A., Johnson, M. A., Jones, J. M., Jones, S. A., Jonsell, Svante, Khramov, A., Knapp, P., Kurchaninov, L., Madsen, N., Maxwell, D., McKenna, J. T. K., Menary, S., Michan, J. M., Momose, T., Munich, J. J., Olchanski, K., Olin, A., Pusa, P., Rasmussen, C. Ø., Robicheaux, F., Sacramento, R. L., Sameed, M., Sarid, E., Silveira, D. M., So, C., Starko, D. M., Stutter, G., Tharp, T. D., Thompson, R. I., van der Werf, D. P., and Wurtele, J. S.

Abstract

At the historic Shelter Island Conference on the Foundations of Quantum Mechanics in 1947, Willis Lamb reported an unexpected feature in the fine structure of atomic hydrogen: a separation of the 2S(1/2) and 2P(1/2) states(1). The observation of this separation, now known as the Lamb shift, marked an important event in the evolution of modern physics, inspiring others to develop the theory of quantum electrodynamics(2-5). Quantum electrodynamics also describes antimatter, but it has only recently become possible to synthesize and trap atomic antimatter to probe its structure. Mirroring the historical development of quantum atomic physics in the twentieth century, modern measurements on anti-atoms represent a unique approach for testing quantum electrodynamics and the foundational symmetries of the standard model. Here we report measurements of the fine structure in the n = 2 states of antihydrogen, the antimatter counterpart of the hydrogen atom. Using optical excitation of the 1S-2P Lyman-alpha transitions in antihydrogen(6), we determine their frequencies in a magnetic field of 1 tesla to a precision of 16 parts per billion. Assuming the standard Zeeman and hyperfine interactions, we infer the zero-field fine-structure splitting (2P(1/2)-2P(3/2)) in antihydrogen. The resulting value is consistent with the predictions of quantum electrodynamics to a precision of 2 per cent. Using our previously measured value of the 1S-2S transition frequency(6,7), we find that the classic Lamb shift in antihydrogen (2S(1/2)-2P(1/2) splitting at zero field) is consistent with theory at a level of 11 per cent. Our observations represent an important step towards precision measurements of the fine structure and the Lamb shift in the antihydrogen spectrum as tests of the charge-parity-time symmetry(8) and towards the determination of other fundamental quantities, such as the antiproton charge radius(9,10), in this antimatter system. Precision measurements of the 1S-2P transition in an

Published
2020
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18. Observation of the 1S-2P Lyman-alpha transition in antihydrogen

Author

Ahmadi, M., Alves, B. X. R., Baker, C. J., Bertsche, W., Capra, A., Carruth, C., Cesar, C. L., Charlton, M., Cohen, S., Collister, R., Eriksson, S., Evans, A., Evetts, N., Fajans, J., Friesen, T., Fujiwara, M. C., Gill, D. R., Hangst, J. S., Hardy, W. N., Hayden, M. E., Hunter, E. D., Isaac, C. A., Johnson, M. A., Jones, J. M., Jones, S. A., Jonsell, Svante, Khramov, A., Knapp, P., Kurchaninov, L., Madsen, N., Maxwell, D., McKenna, J. T. K., Menary, S., Michan, J. M., Momose, T., Munich, J. J., Olchanski, K., Olin, A., Pusa, P., Rasmussen, C. O., Robicheaux, F., Sacramento, R. L., Sameed, M., Sarid, E., Silveira, D. M., Starko, D. M., Stutter, G., So, C., Tharp, T. D., Thompson, R. I., van der Werf, D. P., Wurtele, J. S., Ahmadi, M., Alves, B. X. R., Baker, C. J., Bertsche, W., Capra, A., Carruth, C., Cesar, C. L., Charlton, M., Cohen, S., Collister, R., Eriksson, S., Evans, A., Evetts, N., Fajans, J., Friesen, T., Fujiwara, M. C., Gill, D. R., Hangst, J. S., Hardy, W. N., Hayden, M. E., Hunter, E. D., Isaac, C. A., Johnson, M. A., Jones, J. M., Jones, S. A., Jonsell, Svante, Khramov, A., Knapp, P., Kurchaninov, L., Madsen, N., Maxwell, D., McKenna, J. T. K., Menary, S., Michan, J. M., Momose, T., Munich, J. J., Olchanski, K., Olin, A., Pusa, P., Rasmussen, C. O., Robicheaux, F., Sacramento, R. L., Sameed, M., Sarid, E., Silveira, D. M., Starko, D. M., Stutter, G., So, C., Tharp, T. D., Thompson, R. I., van der Werf, D. P., and Wurtele, J. S.

Abstract

In 1906, Theodore Lyman discovered his eponymous series of transitions in the extreme-ultraviolet region of the atomic hydrogen spectrum(1,2). The patterns in the hydrogen spectrum helped to establish the emerging theory of quantum mechanics, which we now know governs the world at the atomic scale. Since then, studies involving the Lyman-alpha line-the 1S-2P transition at a wavelength of 121.6 nanometres-have played an important part in physics and astronomy, as one of the most fundamental atomic transitions in the Universe. For example, this transition has long been used by astronomers studying the intergalactic medium and testing cosmological models via the so-called 'Lyman-alpha forest('3) of absorption lines at different redshifts. Here we report the observation of the Lyman-alpha transition in the antihydrogen atom, the antimatter counterpart of hydrogen. Using narrow-line-width, nanosecond-pulsed laser radiation, the 1S-2P transition was excited in magnetically trapped antihydrogen. The transition frequency at a field of 1.033 tesla was determined to be 2,466,051.7 +/- 0.12 gigahertz (1 sigma uncertainty) and agrees with the prediction for hydrogen to a precision of 5 x 10(-8). Comparisons of the properties of antihydrogen with those of its well-studied matter equivalent allow precision tests of fundamental symmetries between matter ;and antimatter. Alongside the ground-state hyperfine(4,5) and 1S-2S transitions(6,7) recently observed in antihydrogen, the Lyman-alpha transition will permit laser cooling of antihydrogen(8,9), thus providing a cold and dense sample of anti-atoms for precision spectroscopy and gravity measurements(10). In addition to the observation of this fundamental transition, this work represents both a decisive technological step towards laser cooling of antihydrogen, and the extension of antimatter spectroscopy to quantum states possessing orbital angular momentum.

Published
2018
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19. Enhanced Control and Reproducibility of Non-Neutral Plasmas

Author

Ahmadi, M., Alves, B. X. R., Baker, C. J., Bertsche, W., Capra, A., Carruth, C., Cesar, C. L., Charlton, M., Cohen, S., Collister, R., Eriksson, S., Evans, A., Evetts, N., Fajans, J., Friesen, T., Fujiwara, M. C., Gill, D. R., Hangst, J. S., Hardy, W. N., Hayden, M. E., Isaac, C. A., Johnson, M. A., Jones, S. A., Jonsell, Svante, Kurchaninov, L., Madsen, N., Mathers, M., Maxwell, D., McKenna, J. T. K., Menary, S., Momose, T., Munich, J. J., Olchanski, K., Olin, A., Pusa, P., Rasmussen, C. O., Robicheaux, F., Sacramento, R. L., Sameed, M., Sarid, E., Silveira, D. M., So, C., Stutter, G., Tharp, T. D., Thompson, J. E., Thompson, R. I., van der Werf, D. P., Wurtele, J. S., Ahmadi, M., Alves, B. X. R., Baker, C. J., Bertsche, W., Capra, A., Carruth, C., Cesar, C. L., Charlton, M., Cohen, S., Collister, R., Eriksson, S., Evans, A., Evetts, N., Fajans, J., Friesen, T., Fujiwara, M. C., Gill, D. R., Hangst, J. S., Hardy, W. N., Hayden, M. E., Isaac, C. A., Johnson, M. A., Jones, S. A., Jonsell, Svante, Kurchaninov, L., Madsen, N., Mathers, M., Maxwell, D., McKenna, J. T. K., Menary, S., Momose, T., Munich, J. J., Olchanski, K., Olin, A., Pusa, P., Rasmussen, C. O., Robicheaux, F., Sacramento, R. L., Sameed, M., Sarid, E., Silveira, D. M., So, C., Stutter, G., Tharp, T. D., Thompson, J. E., Thompson, R. I., van der Werf, D. P., and Wurtele, J. S.

Abstract

The simultaneous control of the density and particle number of non-neutral plasmas confined in Penning-Malmberg traps is demonstrated. Control is achieved by setting the plasma's density by applying a rotating electric field while simultaneously fixing its axial potential via evaporative cooling. This novel method is particularly useful for stabilizing positron plasmas, as the procedures used to collect positrons from radioactive sources typically yield plasmas with variable densities and particle numbers; it also simplifies optimization studies that require plasma parameter scans. The reproducibility achieved by applying this technique to the positron and electron plasmas used by the ALPHA antihydrogen experiment at CERN, combined with other developments, contributed to a 10-fold increase in the antiatom trapping rate.

Published
2018
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20. Source of slow lithium atoms from Ne or H2 matrix isolation sublimation.

Author

Sacramento, R. L., Alves, B. X., Almeida, D. T., Wolff, W., Li, M. S., and Cesar, C. L.

Subjects
*LITHIUM, *ATOMS, *VELOCITY distribution (Statistical mechanics), *LOW temperature engineering, *NEON, *HYDROGEN, *SUBLIMATION (Chemistry)
Abstract

We have studied, via laser absorption spectroscopy, the velocity distribution of 7Li atoms released from cryogenic matrices of solid neon or molecular hydrogen. The Li atoms are implanted into the Ne or H2 matrices - grown onto a sapphire substrate - by laser ablation of a solid Li or LiH precursor. A heat pulse is then applied to the sapphire substrate sublimating the matrix together with the isolated atoms. With a NiCr film resistor deposited directly onto the sapphire substrate we are able to transfer high instantaneous power to the matrix, thus reaching a fast sublimation regime. In this regime the Li atoms can get entrained in the released matrix gas, and we were also able to achieve matrix sublimation times down to 10 μs for both H2 or Ne matrix, enabling us to proceed with the trapping of the species of our interest such as atomic hydrogen, lithium, and molecules. The sublimation of the H2 matrix, with its large center-of-mass velocity, provides evidence for a new regime of one-dimensional thermalization. The laser ablated Li seems to penetrate the H2 matrix deeper than it does in Ne. [ABSTRACT FROM AUTHOR]

Published
2012
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21. Spectroscopy of lithium atoms sublimated from isolation matrix of solid Ne.

Author

Sacramento, R. L., Scudeller, L. A., Lambo, R., Crivelli, P., and Cesar, C. L.

Subjects
*MATRIX isolation spectroscopy, *LITHIUM, *LASER ablation, *NEON, *TEMPERATURE effect, *AXIAL loads, *SUBLIMATION (Chemistry)
Abstract

We have studied, via laser absorption spectroscopy, the velocity distribution of 7Li atoms released from a solid neon matrix at cryogenic temperatures. The Li atoms are implanted into the Ne matrix by laser ablation of a solid Li precursor. A heat pulse is then applied to the sapphire substrate sublimating the matrix together with the isolated atoms at around 12 K. We find interesting differences in the velocity distribution of the released Li atoms from the model developed for our previous experiment with Cr [R. Lambo, C. C. Rodegheri, D. M. Silveira, and C. L. Cesar, Phys. Rev. A 76, 061401(R) (2007)]. This may be due to the sublimation regime, which is at much lower flux for the Li experiment than for the Cr experiment, as well as to the different collisional cross sections between those species to the Ne gas. We find a drift velocity compatible with Li being thermally sublimated at 11-13 K, while the velocity dispersion around this drift velocity is low, around 5-7 K. With a slow sublimation of the matrix we can determine the penetration depth of the laser ablated Li atoms into the Ne matrix, an important information that is not usually available in most matrix isolation spectroscopy setups. The present results with Li, together with the previous results with Cr suggest this to be a general technique for obtaining cryogenic atoms, for spectroscopic studies, as well as for trap loading. The release of the isolated atoms is also a useful tool to study and confirm details of the matrix isolated atoms which are masked or poorly understood in the solid. [ABSTRACT FROM AUTHOR]

Published
2011
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22. Antihydrogen accumulation for fundamental symmetry tests

Author

Ahmadi, M., Alves, B. X. R., Baker, C. J., Bertsche, W., Butler, E., Capra, A., Carruth, C., Cesar, C. L., Charlton, M., Cohen, S., Collister, R., Eriksson, S., Evans, A., Evetts, N., Fajans, J., Friesen, T., Fujiwara, M. C., Gill, D. R., Gutierrez, A., Hangst, J. S., Hardy, W. N., Hayden, M. E., Isaac, C. A., Ishida, A., Johnson, M. A., Jones, S. A., Jonsell, Svante, Kurchaninov, L., Madsen, N., Mathers, M., Maxwell, D., McKenna, J. T. K., Menary, S., Michan, J. M., Momose, T., Munich, J. J., Nolan, P., Olchanski, K., Olin, A., Pusa, P., Rasmussen, C. Ø., Robicheaux, F., Sacramento, R. L., Sameed, M., Sarid, E., Silveira, D. M., Stracka, S., Stutter, G., So, C., Tharp, T. D., Thompson, J. E., Thompson, R. I., van der Werf, D. P., Wurtele, J. S., Ahmadi, M., Alves, B. X. R., Baker, C. J., Bertsche, W., Butler, E., Capra, A., Carruth, C., Cesar, C. L., Charlton, M., Cohen, S., Collister, R., Eriksson, S., Evans, A., Evetts, N., Fajans, J., Friesen, T., Fujiwara, M. C., Gill, D. R., Gutierrez, A., Hangst, J. S., Hardy, W. N., Hayden, M. E., Isaac, C. A., Ishida, A., Johnson, M. A., Jones, S. A., Jonsell, Svante, Kurchaninov, L., Madsen, N., Mathers, M., Maxwell, D., McKenna, J. T. K., Menary, S., Michan, J. M., Momose, T., Munich, J. J., Nolan, P., Olchanski, K., Olin, A., Pusa, P., Rasmussen, C. Ø., Robicheaux, F., Sacramento, R. L., Sameed, M., Sarid, E., Silveira, D. M., Stracka, S., Stutter, G., So, C., Tharp, T. D., Thompson, J. E., Thompson, R. I., van der Werf, D. P., and Wurtele, J. S.

Abstract

Antihydrogen, a positron bound to an antiproton, is the simplest anti-atom. Its structure and properties are expected to mirror those of the hydrogen atom. Prospects for precision comparisons of the two, as tests of fundamental symmetries, are driving a vibrant programme of research. In this regard, a limiting factor in most experiments is the availability of large numbers of cold ground state antihydrogen atoms. Here, we describe how an improved synthesis process results in a maximum rate of 10.5 +/- 0.6 atoms trapped and detected per cycle, corresponding to more than an order of magnitude improvement over previous work. Additionally, we demonstrate how detailed control of electron, positron and antiproton plasmas enables repeated formation and trapping of antihydrogen atoms, with the simultaneous retention of atoms produced in previous cycles. We report a record of 54 detected annihilation events from a single release of the trapped anti-atoms accumulated from five consecutive cycles.

Published
2017
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23. Erratum: Observation of the hyperfine spectrum of antihydrogen

Author

Ahmadi, M., primary, Alves, B. X. R., additional, Baker, C. J., additional, Bertsche, W., additional, Butler, E., additional, Capra, A., additional, Carruth, C., additional, Cesar, C. L., additional, Charlton, M., additional, Cohen, S., additional, Collister, R., additional, Eriksson, S., additional, Evans, A., additional, Evetts, N., additional, Fajans, J., additional, Friesen, T., additional, Fujiwara, M. C., additional, Gill, D. R., additional, Gutierrez, A., additional, Hangst, J. S., additional, Hardy, W. N., additional, Hayden, M. E., additional, Isaac, C. A., additional, Ishida, A., additional, Johnson, M. A., additional, Jones, S. A., additional, Jonsell, S., additional, Kurchaninov, L., additional, Madsen, N., additional, Mathers, M., additional, Maxwell, D., additional, McKenna, J. T. K., additional, Menary, S., additional, Michan, J. M., additional, Momose, T., additional, Munich, J. J., additional, Nolan, P., additional, Olchanski, K., additional, Olin, A., additional, Pusa, P., additional, Rasmussen, C. Ø., additional, Robicheaux, F., additional, Sacramento, R. L., additional, Sameed, M., additional, Sarid, E., additional, Silveira, D. M., additional, Stracka, S., additional, Stutter, G., additional, So, C., additional, Tharp, T. D., additional, Thompson, J. E., additional, Thompson, R. I., additional, van der Werf, D. P., additional, and Wurtele, J. S., additional

Published
2017
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24. Antihydrogen accumulation for fundamental symmetry tests

Author

Ahmadi, M., primary, Alves, B. X. R., additional, Baker, C. J., additional, Bertsche, W., additional, Butler, E., additional, Capra, A., additional, Carruth, C., additional, Cesar, C. L., additional, Charlton, M., additional, Cohen, S., additional, Collister, R., additional, Eriksson, S., additional, Evans, A., additional, Evetts, N., additional, Fajans, J., additional, Friesen, T., additional, Fujiwara, M. C., additional, Gill, D. R., additional, Gutierrez, A., additional, Hangst, J. S., additional, Hardy, W. N., additional, Hayden, M. E., additional, Isaac, C. A., additional, Ishida, A., additional, Johnson, M. A., additional, Jones, S. A., additional, Jonsell, S., additional, Kurchaninov, L., additional, Madsen, N., additional, Mathers, M., additional, Maxwell, D., additional, McKenna, J. T. K., additional, Menary, S., additional, Michan, J. M., additional, Momose, T., additional, Munich, J. J., additional, Nolan, P., additional, Olchanski, K., additional, Olin, A., additional, Pusa, P., additional, Rasmussen, C. Ø., additional, Robicheaux, F., additional, Sacramento, R. L., additional, Sameed, M., additional, Sarid, E., additional, Silveira, D. M., additional, Stracka, S., additional, Stutter, G., additional, So, C., additional, Tharp, T. D., additional, Thompson, J. E., additional, Thompson, R. I., additional, van der Werf, D. P., additional, and Wurtele, J. S., additional

Published
2017
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26. Observation of the 1S–2S transition in trapped antihydrogen

Author

Ahmadi, M., primary, Alves, B. X. R., additional, Baker, C. J., additional, Bertsche, W., additional, Butler, E., additional, Capra, A., additional, Carruth, C., additional, Cesar, C. L., additional, Charlton, M., additional, Cohen, S., additional, Collister, R., additional, Eriksson, S., additional, Evans, A., additional, Evetts, N., additional, Fajans, J., additional, Friesen, T., additional, Fujiwara, M. C., additional, Gill, D. R., additional, Gutierrez, A., additional, Hangst, J. S., additional, Hardy, W. N., additional, Hayden, M. E., additional, Isaac, C. A., additional, Ishida, A., additional, Johnson, M. A., additional, Jones, S. A., additional, Jonsell, S., additional, Kurchaninov, L., additional, Madsen, N., additional, Mathers, M., additional, Maxwell, D., additional, McKenna, J. T. K., additional, Menary, S., additional, Michan, J. M., additional, Momose, T., additional, Munich, J. J., additional, Nolan, P., additional, Olchanski, K., additional, Olin, A., additional, Pusa, P., additional, Rasmussen, C. Ø., additional, Robicheaux, F., additional, Sacramento, R. L., additional, Sameed, M., additional, Sarid, E., additional, Silveira, D. M., additional, Stracka, S., additional, Stutter, G., additional, So, C., additional, Tharp, T. D., additional, Thompson, J. E., additional, Thompson, R. I., additional, van der Werf, D. P., additional, and Wurtele, J. S., additional

Published
2016
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32. Silicon vertex detector upgrade in the ALPHA experiment

Author

Amole, C., Andresen, G. B., Ashkezari, M. D., Baquero-Ruiz, M., Bertsche, W., Burrows, C., Butler, E., Capra, A., Cesar, C. L., Chapman, S., Charlton, M., Deller, A., Eriksson, S., Fajans, J., Friesen, T., Fujiwara, M. C., Gill, D. R., Gutierrez, A., Hangst, J. S., Hardy, W. N., Hayden, M. E., Humphries, A. J., Isaac, C. A., Jonsell, Svante, Kurchaninov, L., Little, A., Madsen, N., McKenna, J. T. K., Menary, S., Napoli, S. C., Nolan, P., Olchanski, K., Olin, A., Povilus, A., Pusa, P., Rasmussen, C. O., Robicheaux, F., Sacramento, R. L., Stracka, S., Sampson, J. A., Sarid, E., Seddon, D., Silveira, D. M., So, C., Thompson, R. I., Tharp, T., Thornhill, J., Tooley, M. P., van der Werf, D. P., Wells, D., Amole, C., Andresen, G. B., Ashkezari, M. D., Baquero-Ruiz, M., Bertsche, W., Burrows, C., Butler, E., Capra, A., Cesar, C. L., Chapman, S., Charlton, M., Deller, A., Eriksson, S., Fajans, J., Friesen, T., Fujiwara, M. C., Gill, D. R., Gutierrez, A., Hangst, J. S., Hardy, W. N., Hayden, M. E., Humphries, A. J., Isaac, C. A., Jonsell, Svante, Kurchaninov, L., Little, A., Madsen, N., McKenna, J. T. K., Menary, S., Napoli, S. C., Nolan, P., Olchanski, K., Olin, A., Povilus, A., Pusa, P., Rasmussen, C. O., Robicheaux, F., Sacramento, R. L., Stracka, S., Sampson, J. A., Sarid, E., Seddon, D., Silveira, D. M., So, C., Thompson, R. I., Tharp, T., Thornhill, J., Tooley, M. P., van der Werf, D. P., and Wells, D.

Abstract

The Silicon Vertex Detector (SVD) is the main diagnostic tool in the ALPHA-experiment. It provides precise spatial and timing information of antiproton (antihydrogen) annihilation events (vertices), and most importantly, the SVD is capable of directly identifying and analysing single annihilation events, thereby forming the basis of ALPHA's analysis. This paper describes the ALPHA SVD and its upgrade, installed in the ALPHA's new neutral atom trap., AuthorCount:50

Published
2013
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34. Enhanced Control and Reproducibility of Non-Neutral Plasmas.

Author

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 SA, Jonsell S, Kurchaninov L, Madsen N, Mathers M, 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, So C, Stutter G, Tharp TD, Thompson JE, Thompson RI, van der Werf DP, and Wurtele JS

Abstract

The simultaneous control of the density and particle number of non-neutral plasmas confined in Penning-Malmberg traps is demonstrated. Control is achieved by setting the plasma's density by applying a rotating electric field while simultaneously fixing its axial potential via evaporative cooling. This novel method is particularly useful for stabilizing positron plasmas, as the procedures used to collect positrons from radioactive sources typically yield plasmas with variable densities and particle numbers; it also simplifies optimization studies that require plasma parameter scans. The reproducibility achieved by applying this technique to the positron and electron plasmas used by the ALPHA antihydrogen experiment at CERN, combined with other developments, contributed to a 10-fold increase in the antiatom trapping rate.

Published
2018
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