Conference Proceedings (refereed)

Conference Proceeding (refereed)

The ALPHA-g Antihydrogen Gravity Magnet System

Conference Proceeding (refereed)

The ALPHA-g experiment at CERN aims to perform the first-ever precision measurement of the weight of antimatter, using antihydrogen atoms confined in a magnetic trap. In the measurement, anti-atoms are allowed to escape through either a lower or an upper port in the trap, the up-down balance of which depends on gravity and the trap field at the ports.

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Published in

IEEE Transactions on Applied Superconductivity

Chukman So, Joel Fajans, William Bertsche

Machine learning for antihydrogen detection at ALPHA

Conference Proceeding (refereed)
The ALPHA experiment at CERN is designed to produce and trap antihydrogen to the purpose of making a precise comparison with hydrogen. The basic technique consists of driving an antihydrogen resonance which will cause the antiatom to leave the trap and annihilate. [...]
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Published in

Journal of Physics: Conference Series

Andrea Capra for the ALPHA Collaboration

Lifetime of magnetically trapped antihydrogen in ALPHA

Conference Proceeding (refereed)

How long antihydrogen atoms linger in the ALPHA magnetic trap is an important characteristic of the ALPHA apparatus. The initial trapping experiments in 2010 (Andresen Nature 468, 673–676, 2010) were conducted with 38 detected antiatoms confined for 172 ms and in 2011 (Andresen Nature Phys. 7, 558–564, 2011) with seven for 1000 s.

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Published in

Conference on Low Energy Antiproton Physics (LEAP 2018)

Andrea Capra & ALPHA Collaboration

Prospects for comparison of matter and antimatter gravitation with ALPHA-g

Conference Proceeding (refereed)
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. [...]
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Published in

Royal Society Publishing

William Bertsche

Precision measurements on trapped antihydrogen in the ALPHA experiment

Conference Proceeding (refereed)
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. [...]
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Published in

Royal Society Publishing

Stefan Eriksson

Antiproton physics in the ELENA era

Conference Proceeding (refereed)
The programme of physics with low-energy antiprotons at CERN, the European Particle Physics Laboratory, has a long history, beginning with the inauguration of the Low Energy Antiproton Ring (LEAR) in 1982. [...]
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Published in

Royal Society Publishing

Niels Madsen

Antiproton cloud compression in the ALPHA apparatus at CERN

Conference Proceeding (refereed)
We have observed a new mechanism for compression of a non-neutral plasma, where antiprotons embedded in an electron plasma are compressed by a rotating wall drive at a frequency close to the sum of the axial bounce and rotation frequencies. [...]
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Published in

Hyperfine Interactions

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

Silicon vertex detector upgrade in the ALPHA experiment

Conference Proceeding (refereed)
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. [...]
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Published in

Nuclear Instruments and Methods in Physics Research A

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

Evaporative cooling of antiprotons for the production of trappable antihydrogen

Conference Proceeding (refereed)
We describe the implementation of evaporative cooling of charged particles in the ALPHA apparatus. Forced evaporation has been applied to cold samples of antiprotons held in Malmberg-Penning traps. Temperatures on the order of 10 K were obtained, while retaining a significant fraction of the initial number of particles. [...]
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Published in

AIP Conference Proceedings

Silveira, D. M., Andresen, G. B., Ashkezari, M. D., Baquero-Ruiz, M., Bertsche, W., Bowe, P. D., Butler, E., Cesar, C. L., Chapman, S., Charlton, M., Fajans, J., Friesen, T., Fujiwara, M. C., Gill, D. R., Hangst, J. S., Hardy, W. N., Hayden, M. E., Hydomako, R., Jonsell, S., Kurchaninov, L., Madsen, N., Menary, S., Nolan, P., Olchanski, K., Olin, A., Povilus, A., Pusa, P., Robicheaux, F., Sarid, E., So, C., Storey, J. W., Thompson, R. I., van der Werf, D. P., Wurtele, J. S.

Electron plasmas as a diagnostic tool for hyperfine spectroscopy of antihydrogen

Conference Proceeding (refereed)
Long term magnetic confinement of antihydrogen atoms has recently been demonstrated by the ALPHA collaboration at CERN, opening the door to a range of experimental possibilities. Of particular interest is a measurement of the antihydrogen spectrum. [...]
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Published in

AIP Conference Proceedings

Friesen, T., Amole, C., Ashkezari, M. D., Baquero-Ruiz, M., Bertsche, W., Bowe, P. D., Butler, E., Capra, A., Cesar, C. L., Charlton, M., Deller, A., Evetts, N., Eriksson, S., Fajans, J., Fujiwara, M. C., Gill, D. R., Gutierrez, A., 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., Olchanski, K., Olin, A., Pusa, P., Rasmussen, C. Ø., Robicheaux, F., Sarid, E., Silveira, D. M., So, C., Stracka, S., Thompson, R. I., van der Werf, D. P., Wurtele, J. S.

Antihydrogen formation by autoresonant excitation of antiproton plasmas

Conference Proceeding (refereed)
In efforts to trap antihydrogen, a key problem is the vast disparity between the neutral trap energy scale (∼ 50 μeV), and the energy scales associated with plasma confinement and space charge (∼ 1 eV). In order to merge charged particle species for direct recombination, the larger energy scale must be overcome in a manner that minimizes the initial antihydrogen kinetic energy. [...]
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Published in

Hyperfine Interactions

Bertsche, W. A., Andresen, G. B., Ashkezari, M. D., Baquero-Ruiz, M., Bowe, P. D., Carpenter, P. T., Butler, E., Cesar, C. L., Chapman, S. F., Charlton, M., Eriksson, S., Fajans, J., Friesen, T., Fujiwara, M. C., Gill, D. R., Gutierrez, A., Hangst, J. S., Hardy, W. N., Hayano, R. S., Hayden, M. E., Humphries, A. J., Hurt, J. L., Hydomako, R., Jonsell, S., Kurchaninov, L., Madsen, N., Menary, S., Nolan, P., Olchanski, K., Olin, A., Povilus, A., Pusa, P., Robicheaux, F., Sarid, E., Silveira, D. M., So, C., Storey, J. W., Thompson, R. I., Werf, D. P. van der, Wurtele, J. S., Yamazaki, Y.

Alternative method for reconstruction of antihydrogen annihilation vertices

Conference Proceeding (refereed)
The ALPHA experiment, located at CERN, aims to compare the properties of antihydrogen atoms with those of hydrogen atoms. The neutral antihydrogen atoms are trapped using an octupole magnetic trap. [...]
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Published in

Hyperfine Interactions

C. Amole, M. D. Ashkezari, G. B. Andresen , M. Baquero-Ruiz, W. Bertsche, P. D. Bowe, E. Butler, C. L. Cesar, S. Chapman, M. Charlton, A. Deller, S. Eriksson, J. Fajans, T. Friesen, M. C. Fujiwara, D. R. Gill, A. Gutierrez, J. S. Hangst, W. N. Hardy, R. S. Hayano, M. E. Hayden, A. J. Humphries, R. Hydomako, S. Jonsell, L. Kurchaninov, N. Madsen, S. Menary, P. Nolan, K. Olchanski, A. Olin, A. Povilus, P. Pusa, F. Robicheaux, E. Sarid, D. M. Silveira, C. So, J. W. Storey, R. I. Thompson, D. P. van derWerf, J. S. Wurtele, Y. Yamazaki

Progress towards microwave spectroscopy of trapped antihydrogen

Conference Proceeding (refereed)
Precision comparisons of hyperfine intervals in atomic hydrogen and antihydrogen are expected to yield experimental tests of the CPT theorem. The CERN-based ALPHA collaboration has initiated a program of study focused on microwave spectroscopy of trapped ground-state antihydrogen atoms. [...]
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Published in

Hyperfine Interactions

M.D. Ashkezari, G.B. Andresen, M. Baquero-Ruiz, W. Bertsche, P.D. Bowe, E. Butler, C.L. Cesar, S. Chapman, M. Charlton, A. Deller, S. Eriksson, J. Fajans, T. Friesen, M.C. Fujiwara, D.R. Gill, A. Gutierrez, J.S. Hangst, W.N. Hardy, M.E. Hayden, A.J. Humphries, R. Hydomako, S. Jonsell, L. Kurchaninov, N. Madsen, S. Menary, P. Nolan, K. Olchanski, A. Olin, A. Povilus, P. Pusa, F. Robicheaux, E. Sarid, D.M. Silveira, C. So, J.W. Storey, R.I. Thompson, D.P. van der Werf, J.S. Wurtele, Y. Yamazaki

Trapped Antihydrogen

Conference Proceeding (refereed)
Precision spectroscopic comparison of hydrogen and antihydrogen holds the promise of a sensitive test of the Charge-Parity-Time theorem and matter-antimatter equivalence. The clearest path towards realising this goal is to hold a sample of antihydrogen in an atomic trap for interrogation by electromagnetic radiation. [...]
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Published in

Hyperfine Interactions

E. Butler, G.B. Andresen, M.D. Ashkezari, M. Baquero-Ruiz, W. Bertsche, P.D. Bowe, C.L. Cesar, S. Chapman, M. Charlton, A. Deller, S. Eriksson, J. Fajans, T. Friesen, M.C. Fujiwara, D.R. Gill, A. Gutierrez, J.S. Hangst, W.N. Hardy, M.E. Hayden, A.J. Humphries, R. Hydomako, M.J. Jenkins, S. Jonsell, L.V. Jørgensen, S.L. Kemp, L. Kurchaninov, N. Madsen, S. Menary, P. Nolan, K. Olchanski, A. Olin, A. Povilus, P. Pusa, C. Ø. Rasmussen, F. Robicheaux, E. Sarid, S. Seif el Nasr, D.M. Silveira, C. So, J.W. Storey, R.I. Thompson, D.P. van der Werf, J.S. Wurtele, Y. Yamazaki

Towards antihydrogen trapping and spectroscopy at ALPHA

Conference Proceeding (refereed)
Spectroscopy of antihydrogen has the potential to yield high-precision tests of the CPT theorem and shed light on the matter-antimatter imbalance in the Universe. The ALPHA antihydrogen trap at CERN's Antiproton Decelerator aims to prepare a sample of antihydrogen atoms confined in an octupole-based Ioffe trap and to measure the frequency of several atomic transitions. [...]
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Published in

Hyperfine Interactions

Butler, E., Andresen, G. B., Ashkezari, M. D., Baquero-Ruiz, M., Bertsche, W., Bowe, P. D., Bray, C. C., Cesar, C. L., Chapman, S., Charlton, M., Fajans, J., Friesen, T., Fujiwara, M. C., Gill, D. R., Hangst, J. S., Hardy, W. N., Hayano, R. S., Hayden, M. E., Humphries, A. J., Hydomako, R., Jonsell, S., Kurchaninov, L., Lambo, R., Madsen, N., Menary, S., Nolan, P., Olchanski, K., Olin, A., Povilus, A., Pusa, P., Robicheaux, F., Sarid, E., Silveira, D. M., So, C., Storey, J. W., Thompson, R. I., van der Werf, D. P., Wilding, D., Wurtele, J. S., Yamazaki, Y.

Search for trapped antihydrogen in ALPHA

Conference Proceeding (refereed)
Antihydrogen spectroscopy promises precise tests of the symmetry of matter and antimatter, and can possibly offer new insights into the baryon asymmetry of the universe. Antihydrogen is, however, difficult to synthesize and is produced only in small quantities. [...]
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Published in

Canadian Journal of Physics

N. Madsen, G. B. Andresen, M. D. Ashkezari, M. Baquero-Ruiz, W. Bertsche, P. D. Bowe, C. Bray, E. Butler, C. L. Cesar, S. Chapman, M. Charlton, J. Fajans, T. Friesen, M. C. Fujiwara, D. R. Gill, J. S. Hangst, W. N. Hardy, M. E. Hayden, A. J. Humphries, R. Hydomako, S. Jonsell, L. V. Jørgensen, L. Kurchaninov, R. Lambo, S. Menary, P. Nolan, K. Olchanski, A. Olin, A. Povilus, P. Pusa, F. Robicheaux, E. Sarid, S. Seif El Nasr, D. M. Silveira, C. So, J. W. Storey, R. I. Thompson, D. P. van der Werf, J. S. Wurtele, and Y. Yamazaki

Antihydrogen Physics at ALPHA/CERN

Conference Proceeding (refereed)
Cold antihydrogen has been produced at CERN (Amoretti et al. (Nature, 419, 456 (2002)), Gabrielse et al. (Phys. Rev. Lett. 89, 213401 (2002))), with the aim of performing a high-precision spectroscopic comparison with hydrogen as a test of the CPT symmetry. [...]
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Published in

Canadian Journal of Physics

C. L. Cesar, G. B. Andresen, W. Bertsche, P. D. Bowe, C. C. Bray, E. Butler, S. Chapman, M. Charlton, J. Fajans, M. C. Fujiwara, R. Funakoshi, D. R. Gill, J. S. Hangst, W. N. Hardy, R. S. Hayano, M. E. Hayden, A. J. Humphries, R. Hydomako, M. J. Jenkins, L. V. Jørgensen, L. Kurchaninov, R. Lambo, N. Madsen, P. Nolan, K. Olchanski, A. Olin, R. D. Page, A. Povilus, P. Pusa, F. Robicheaux, E. Sarid, S. Seif El Nasr, D. M. Silveira, J. W. Storey, R. I. Thompson, D. P. van der Werf, J. S. Wurtele, and Y. Yamazaki

Towards Trapped Antihydrogen

Conference Proceeding (refereed)
Substantial progress has been made in the last few years in the nascent field of antihydrogen physics. The next big step forward is expected to be the trapping of the formed antihydrogen atoms using a magnetic multipole trap. [...]
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Published in

Nuclear Instruments and Methods in Physics Research Section B

L.V. Jørgensen, G. Andresen, W. Bertsche, A. Boston, P.D. Bowe, C.L. Cesar, S. Chapman, M. Charlton, J. Fajans, M.C. Fujiwara, R. Funakoshi, D.R. Gill, J.S. Hangst, R.S. Hayano, R. Hydomako, M.J. Jenkins, L. Kurchaninov, N. Madsen, P. Nolan, K. Olchanski, A. Olin, R.D. Page, A. Povilus, F. Robicheaux, E. Sarid, D.M. Silveira, J.W. Storey, R.I. Thompson, D.P. van der Werf, J.S. Wurtele, and Y. Yamazaki

Towards Antihydrogen Confinement With The ALPHA Antihydrogen Trap

Conference Proceeding (refereed)
ALPHA is an international project that has recently begun experimentation at CERN’s Antiproton Decelerator (AD) facility. [...]
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Published in

Hyperfine Interactions

M. C. Fujiwara, G. Andresen, W. Bertsche, A. Boston, P. D. Bowe, C. L. Cesar, S. Chapman, M. Charlton, M. Chartier, A. Deutsch, J. Fajans, R. Funakoshi, D. R. Gill, K. Gomberoff, J. S. Hangst, W. N. Hardy, R. S. Hayano, R. Hydomako, M. J. Jenkins, L.V. Jørgensen, L. Kurchaninov, N. Madsen, P. Nolan, K. Olchanski, A. Olin, R. D. Page, A. Povilus, F. Robicheaux, E. Sarid, D. M. Silveira, J.W. Storey, R. I. Thompson, D. P. van der Werf, J. S. Wurtele, and Y. Yamazaki