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Refereed Publication

Refereed Publication
19 Feb 2020
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 2S1/2 and 2P1/2 states. 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. Quantum electrodynamics also describes antimatter, but it has only recently become possible to synthesize and trap atomic antimatter to probe its structure. [...]
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M. Ahmadi, B. X. R. Alves, C. J. Baker, W. Bertsche, A. Capra, C. Carruth, C. L. Cesar, M. Charlton, S. Cohen, R. Collister, S. Eriksson, A. Evans, N. Evetts, J. Fajans, T. Friesen, M. C. Fujiwara, D. R. Gill, P. Granum, J. S. Hangst, W. N. Hardy, M. E. Hayden, E. D. Hunter, C. A. Isaac, M. A. Johnson, J. M. Jones, S. A. Jones, S. Jonsell, A. Khramov, P. Knapp, L. Kurchaninov, N. Madsen, D. Maxwell, J. T. K. McKenna, S. Menary, J. M. Michan, T. Momose, J. J. Munich, K. Olchanski, A. Olin, P. Pusa, C. Ø. Rasmussen, F. Robicheaux, R. L. Sacramento, M. Sameed, E. Sarid, D. M. Silveira, C. So, D

In 1906, Theodore Lyman discovered his eponymous series of transitions in the extreme-ultraviolet region of the atomic hydrogen spectrum. 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-α 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. [...]
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M. Ahmadi, B.X.R. Alves, C.J. Baker, W. Bertsche, A. Capra, C. Carruth, C.L. Cesar, M. Charlton, S. Cohen, R. Collister, S. Eriksson, A. Evans, N. Evetts, J. Fajans, T. Friesen, M.C. Fujiwara, D.R. Gill, J.S. Hangst, W.N. Hardy, M.E. Hayden, E.D. Hunter, C.A. Isaac, M.A. Johnson, J.M. Jones, S.A. Jones, S. Jonsell, A. Khramov, P. Knapp, L. Kurchaninov, N. Madsen, D. Maxwell, J.T.K. McKenna, S. Menary, J.M. Michan, T. Momose, J.J. Munich, K. Olchanski, A. Olin, P. Pusa, C.Ø. Rasmussen, F. Robicheaux, R.L. Sacramento, M. Sameed, E. Sarid, D.M. Silveira, D.M. Starko, G. Stutter, C. So, T.D

In 1928, Dirac published an equation 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 (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 antimatter, 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. [...]
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M. Ahmadi, B.X.R. Alves, C.J. Baker, W. Bertsche, A. Capra, C. Carruth, C.L. Cesar, M. Charlton, S. Cohen, R. Collister, S. Eriksson, A. Evans, N. Evetts, J. Fajans, T. Friesen, M.C. Fujiwara, D.R. Gill, J.S. Hangst, W.N. Hardy, M.E. Hayden, C.A. Isaac, M.A. Johnson, J.M. Jones, S.A. Jones, S. Jonsell, A. Khramov, P. Knapp, L. Kurchaninov, N. Madsen, D. Maxwell, J.T.K. McKenna, S. Menary, T. Momose, J.J. Munich, K. Olchanski, A. Olin, P. Pusa, C.Ø. Rasmussen, F. Robicheaux, R.L. Sacramento, M. Sameed, E. Sarid, D.M. Silveira, G. Stutter, C. So, T.D. Tharp, R.I. Thompson, D.P. van der Werf

The nature of the trajectories of antihydrogen atoms confined in an octupole minimum-B trap is of great importance for upcoming spectroscopy, cooling, and gravity experiments. Of particular interest is the mixing time between the axial and transverse energies for the antiatoms. [...]

M. Zhong, J. Fajans and A.F. Zukor

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. [...]

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

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. [...]
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M. Ahmadi, B.X.R. Alves, C.J. Baker, W. Bertsche4, E. Butler , A. Capra, C. Carruth, C.L. Cesar, M. Charlton, S. Cohen, R. Collister, S. Eriksson, A. Evans, N. Evetts, J. Fajans, T. Friesen, M.C. Fujiwara, D.R. Gill, A. Gutierrez, J.S. Hangst, W.N. Hardy, M.E. Hayden, C.A. Isaac, A. Ishida, M.A. Johnson, S.A. Jones, S. Jonsell, L. Kurchaninov, N. Madsen, M. Mathers, D. Maxwell, J.T.K. McKenna, S. Menary, J.M. Michan, T. Momose, J.J. Munich, P. Nolan, K. Olchanski, A. Olin, P. Pusa, C.Ø. Rasmussen, F. Robicheaux, R.L. Sacramento, M. Sameed, E. Sarid, D.M. Silveira, S. Stracka, G. Stutter, C

Antihydrogen atoms are now routinely trapped in small numbers. One of the purposes of this effort is to make precision comparisons of the 1 S -2 S transition in hydrogen and antihydrogen as a precision test of the CPT theorem. We investigate, through calculations and simulations, various methods by which the 1 S -2 S transition may be probed with only a few trapped atoms. [...]
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C. Ø. Rasmussen and N. Madsen and F. Robicheaux

We report the observation of the hyperfine spectrum of antihydrogen. By exposing trapped antihydrogen to microwave radiation and scanning the microwave frequency over two distinct transitions, we are able to extract the ground state hyperfine splitting. [...]
Published in

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. Evans, N. Evetts, J. Fajans, T. Friesen, M.C. Fujiwara, D.R. Gill, A. Gutierrez, J.S. Hangst, W.N. Hardy, M.E. Hayden, C.A. Isaac, A. Ishida, M.A. Johnson, S.A. Jones, S. Jonsell, L. Kurchaninov, N. Madsen, M. Mathers, D. Maxwell, J.T.K. McKenna, S.Menary, J.M. Michan, T. Momose J.J. Munich, P. Nolan, K. Olchanski, A. Olin, P. Pusa, C.Ø. Rasmussen, F. Robicheaux, R.L. Sacramento, M. Sameed, E. Sarid, D.M. Silveira, G. Stutter, C. So, T.D. Tharp

We report the observation of the 1S-2S transition in magnetically trapped atoms of antihydrogen in the ALPHA-2 apparatus at CERN. We determine that the frequency of the transition, driven by two photons from a frequency stabilised laser at 243 nm, is consistent with that expected for hydrogen in the same environment. [...]
Published in

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. Evans, N. Evetts, J. Fajans, T. Friesen, M.C. Fujiwara, D.R. Gill, A. Gutierrez, J.S. Hangst, W.N. Hardy, M.E. Hayden, C.A. Isaac, A. Ishida, M.A. Johnson, S.A. Jones, S. Jonsell, L. Kurchaninov, N. Madsen, M. Mathers, D. Maxwell, J.T.K. McKenna, S.Menary, J.M. Michan, T. Momose J.J. Munich, P. Nolan, K. Olchanski, A. Olin, P. Pusa, C.Ø. Rasmussen, F. Robicheaux, R.L. Sacramento, M. Sameed, E. Sarid, D.M. Silveira, G. Stutter, C. So, T.D. Tharp

Antimatter continues to intrigue physicists because of its apparent absence in the observable Universe. Current theory requires that matter and antimatter appeared in equal quantities after the Big Bang, but the Standard Model of particle physics offers no quantitative explanation for the apparent disappearance of half the Universe. It has recently become possible to study trapped atoms of antihydrogen to search for possible, as yet unobserved, differences in the physical behaviour of matter and antimatter. [...]
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M. Ahmadi , M. Baquero-Ruiz, W. Bertsche, E. Butler, A. Capra, C. Carruth, C. L. Cesar, M. Charlton, A. E. Charman, S. Eriksson, L. T. Evans, N. Evetts, J. Fajans, T. Friesen, M. C. Fujiwara, D. R. Gill, A. Gutierrez, J. S. Hangst, W. N. Hardy, M. E. Hayden, C. A. Isaac, A. Ishida, S. A. Jones, S. Jonsell, L. Kurchaninov, N. Madsen, D. Maxwell, J. T. K. McKenna, S. Menary, J. M. Michan, T. Momose, J. J. Munich, P. Nolan, K. Olchanski, A. Olin, A. Povilus, P. Pusa, C. Ø. Rasmussen, F. Robicheaux, R. L. Sacramento, M. Sameed, E. Sarid, D. M. Silveira, C. So, T. D. Tharp, R. I. Thompson, D. P

Refereed Publication
16 Dec 2015
Performing measurements of the properties of antihydrogen, the bound state of an antiproton and a positron, and comparing the results with those for ordinary hydrogen, has long been seen as a route to test some of the fundamental principles of physics. There has been much experimental progress in this direction in recent years, and antihydrogen is now routinely created and trapped and a range of exciting measurements probing the foundations of modern physics are planned or underway. In this contribution we review the techniques developed to facilitate the capture and manipulation of positrons and antiprotons, along with procedures to bring them together to create antihydrogen. [...]
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W.A. Bertsche, E. Butler, M. Charlton and N. Madsen

Refereed Publication
03 Jun 2014
The properties of antihydrogen are expected to be identical to those of hydrogen, and any differences would constitute a profound challenge to the fundamental theories of physics. The most commonly discussed antiatom-based tests of these theories are searches for antihydrogen-hydrogen spectral differences (tests of CPT (charge-parity-time) invariance) or gravitational differences (tests of the weak equivalence principle). [...]
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C. Amole, M. D. Ashkezari, M. Baquero-Ruiz, W. Bertsche, E. Butler, A. Capra, C. L. Cesar, M. Charlton, S. Eriksson, J. Fajans, T. Friesen, M. C. Fujiwara, D. R. Gill, A. Gutierrez, 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, A. Povilus, P. Pusa, C.Ø. Rasmussen, F. Robicheaux, E. Sarid, D. M. Silveira, C. So, T. D. Tharp, R. I. Thompson, D. P. van der Werf, Z. Vendeiro, J. S. Wurtele, A. I. Zhmoginov, A. E. Charman

We demonstrate a novel detection method for the cyclotron resonance frequency of an electron plasma in a Penning–Malmberg trap. With this technique, the electron plasma is used as an in situ diagnostic tool for the measurement of the static magnetic field and the microwave electric field in the trap. [...]

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

Refereed Publication
01 Jan 2014
The ALPHA collaboration, based at CERN, has recently succeeded in confining cold antihydrogen atoms in a magnetic minimum neutral atom trap and has performed the first study of a resonant transition of the anti-atoms. [...]

C. Amole, G.B. Andresen, M.D. Ashkezari, M. Baquero-Ruiz, W. Bertsche, P.D. Bowe, E. Butler, A. Capra, P.T. Carpenter, C.L. Cesar, S. Chapman, M. Charlton, A. Deller, S. Eriksson,J. Escallier, 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, J.L. Hurt, R. Hydomako, C.A. Isaac, M.J. Jenkins, S. Jonsell, L.V. Jørgensen, S.J. Kerrigan, L. Kurchaninov, N. Madsen, A. Marone, J.T.K. McKenna, S. Menary, P. Nolan, K. Olchanski, A. Olin, B. Parker, A. Povilus, P. Pusa, F. Robicheaux, E. Sarid, D. Seddon, S. Seif El Nasr

The influence of gravity on anti-hydrogen dynamics in magnetic traps is studied. The advantages and disadvantages of various techniques for measuring the ratio of the gravitational mass to the inertial mass of anti-hydrogen are discussed. [...]

A. I. Zhmoginov, A. E. Charman, R. Shalloo, J. Fajans and J. S. Wurtele

Knowledge of the residual gas composition in the ALPHA experiment apparatus is important in our studies of antihydrogen and nonneutral plasmas. A technique based on autoresonant ion extraction from an electrostaticpotential well has been developed that enables the study of the vacuum in our trap. [...]

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

Physicists have long wondered whether the gravitational interactions between matter and antimatter might be different from those between matter and itself. Although there are many indirect indications that no such differences exist and that the weak equivalence principle holds, there have been no direct, free-fall style, experimental tests of gravity on antimatter. [...]
Published in

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

One of the goals of synthesizing and trapping antihydrogen is to study the validity of charge-parity–time symmetry through precision spectroscopy on the anti-atoms, but the trapping yield achieved in recent experiments must be significantly improved before this can be realized. [...]
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C. Amole, M. D. Ashkezari, M. Baquero-Ruiz, W. Bertsche, E. Butler, A. Capra, C. L. Cesar, 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, C. A. Isaac, S. Jonsell, L. Kurchaninov, A. Little, N. Madsen, J. T. K. McKenna, S. Menary, S. C. Napoli, K. Olchanski, A. Olin, P. Pusa, C. Ø. Rasmussen, F. Robicheaux, E. Sarid, C. R. Shields, D. M. Silveira, C. So, S. Stracka, R. I. Thompson, D. P. van der Werf, J. S. Wurtele, A. Zhmoginov, (ALPHA collaboration), and L. Friedland

The ALPHA experiment has succeeded in trapping antihydrogen, a major milestone on the road to spectroscopic comparisons of antihydrogen with hydrogen. An annihilation vertex detector, which determines the time and position of antiproton annihilations, has been central to this achievement. [...]

G.B. Andresen, M.D. Ashkezari, 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, R.S. Hayano, A.J. Humphries, R. Hydomako, S. Jonsell, L.V. Jørgensen, L. Kurchaninov, N. Madsen, S. Menary, P. Nolan, K. Olchanski, A. Olin, A. Povilus, P. Pusa, E. Sarid, S. Seif el Nasri, D.M. Silveira, C. So, J.W. Storey, R.I. Thompson, D.P. van der Werf, Y. Yamazaki

The hydrogen atom is one of the most important and influential model systems in modern physics. Attempts to understand its spectrum are inextricably linked to the early history and development of quantum mechanics. The hydrogen atom’s stature lies in its simplicity and in the accuracy with which its spectrum can be measured 1 and compared to theory. Today its spectrum remains a valuable tool for determining the values of fundamental constants and for challenging the limits of modern physics, including the validity of quantum electrodynamics and—by comparison with measurements on its antimatter counterpart, antihydrogen—the validity of CPT (charge conjugation, parity and time reversal) symmetry. [...]
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C. Amole, M. D. Ashkezari, M. Baquero-Ruiz, W. Bertsche, P. D. Bowe, E. Butler, A. Capra, C. L. Cesar, M. Charlton, A. Deller, P. H. Donnan, 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, 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, E. Sarid, C. R. Shields, D. M. Silveira,S. Stracka, C. So, R. I. Thompson, D. P. van der Werf J. S. Wurtele

Recently, antihydrogen atoms were trapped at CERN in a magnetic minimum (minimum-B) trap formed by superconducting octupole and mirror magnet coils. The trapped antiatoms were detected by rapidly turning off these magnets, thereby eliminating the magnetic minimum and releasing any antiatoms contained in the trap. Once released, these antiatoms quickly hit the trap wall, whereupon the positrons and antiprotons in the antiatoms annihilate. [...]
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C. Amole, G. B. Andresen, M. D. Ashkezari, M. Baquero-Ruiz, W. Bertsche, 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, L. Kurchaninov, S. Jonsell, 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

Refereed Publication
05 Jun 2011
Atoms made of a particle and an antiparticle are unstable, usually surviving less than a microsecond. Antihydrogen, made entirely of antiparticles, is believed to be stable, and it is this longevity that holds the promise of precision studies of matter–antimatter symmetry. We have recently demonstrated trapping of antihydrogen atoms by releasing them after a confinement time of 172 ms. A critical question for future studies is: how long can anti-atoms be trapped? [...]
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G. B. Andresen, M. D. Ashkezari, M. Baquero-Ruiz, W. Bertsche, P. D. Bowe, E. Butler, C. L. Cesar, 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, S. L. Kemp, L. Kurchaninov, N. Madsen, S. Menary, P. Nolan, K. Olchanski, A. Olin, P. Pusa, C. Ø. Rasmussen, 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

Charges in cold, multiple-species, non-neutral plasmas separate radially by mass, forming centrifugally separated states. Here, we report the first detailed measurements of such states in an electron-antiproton plasma, and the first observations of the separation dynamics in any centrifugally separated system. [...]

G.B. Andresen, M.D. Ashkezari, 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, N. Madsen, S. Menary, P. Nolan, 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 and Y. Yamazaki

Refereed Publication
01 Jan 2011
We demonstrate controllable excitation of the center-of-mass longitudinal motion of a thermal antiproton plasma using a swept-frequency autoresonant drive. When the plasma is cold, dense, and highly collective in nature, we observe that the entire system behaves as a single-particle nonlinear oscillator, as predicted by a recent theory. [...]

G.B. Andresen, M. D. Ashkezari, M. Baquero-Ruiz, W. Bertsche, P.D. Bowe, E. Butler, P. T. Carpenter, 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, J. L. Hurt, S. Jonsell, 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, and Y. Yamazaki

Refereed Publication
01 Dec 2010
We present the results of an experiment to search for trapped antihydrogen atoms with the ALPHA antihydrogen trap at the CERN Antiproton Decelerator. Sensitive diagnostics of the temperatures, sizes, and densities of the trapped antiproton and positron plasmas have been developed, which in turn permitted development of techniques to precisely and reproducibly control the initial experimental parameters. [...]

G.B. Andresen, M.D. Ashkezari, M. Baquero-Ruiz, W. Bertsche, P.D. Bowe, C.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, R.S. Hayano, M.E. Hayden, A.J. Humphries, R. Hydomako, S. Jonsell, L.V. Jørgensen, L. Kurchaninov , R. Lambo, N. Madsen, 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, D. Wilding, J.S. Wurtele, and Y. Yamazaki

Refereed Publication
17 Nov 2010
Antimatter was first predicted in 1931, by Dirac. Work with high-energy antiparticles is now commonplace, and anti-electrons are used regularly in the medical technique of positron emission tomography scanning. Antihydrogen, the bound state of an antiproton and a positron, has been produced at low energies at CERN (the European Organization for Nuclear Research) since 2002. [...]
Published in

G. B. Andresen, M. D. Ashkezari, 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, M. J. Jenkins, S. Jonsell, L. V. Jørgensen, L. Kurchaninov, N. Madsen, 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

The year 2002 heralded a breakthrough in antimatter research when the first low energy antihydrogen atoms were produced. Antimatter has inspired both science and fiction writers for many years, but detailed studies have until now eluded science. Antimatter is notoriously difficult to study as it does not readily occur in nature, even though our current understanding of the laws of physics have us expecting that it should make up half of the universe. [...]
We report the application of evaporative cooling to clouds of trapped antiprotons, resulting in plasmas with measured temperature as low as 9 K. We have modeled the evaporation process for charged particles using appropriate rate equations. Good agreement between experiment and theory is observed, permitting prediction of cooling efficiency in future experiments. [...]

G.B. Andresen, M.D. Ashkezari, M. Baquero-Ruiz, W. Bertsche, P.D. Bowe, 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, R.S. Hayano, M.E. Hayden, A. Humphries, R. Hydomako, S. Jonsell, L. Kurchaninov, R. Lambo, 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, D. Wilding, J.S. Wurtele, and Y. Yamazaki

Antihydrogen production in a neutral atom trap formed by an octupole-based magnetic field minimum is demonstrated using field-ionization of weakly bound anti-atoms. Using our unique annihilation imaging detector, we correlate antihydrogen detection by imaging and by field-ionization for the first time. [...]

G.B. Andresen, W. Bertsche, P.D. Bowe, C. Bray, E. Butler, C.L. Cesar, S. Chapman, M. Charlton, J. Fajans, M.C. Fujiwara, D.R. Gill, J.S. Hangst, W.N. Hardy, R.S. Hayano, M.E. Hayden, A.J. Humphries, R. Hydomako, L.V. Jørgensen, S.J. Kerrigan, L. Kurchaninov, R. Lambo, N. Madsen, P. Nolan, K. Olchanski, A. Olin, 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

A microchannel plate (MCP)/phosphor screen assembly has been used to destructively measure the radial profile of cold, confined antiprotons, electrons, and positrons in the ALPHA experiment, with the goal of using these trapped particles for antihydrogen creation and confinement. [...]

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

In many antihydrogen trapping schemes, antiprotons held in a short-well Penning–Malmberg trap are released into a longer well. This process necessarily causes the bounce-averaged rotation frequency \omegar of the antiprotons around the trap axis to pass through zero. [...]
Published in

G. B. Andresen, W. Bertsche, C. C. Bray, E. Butler, C. L. Cesar, S. Chapman, M. Charlton, J. Fajans, M. C. Fujiwara, D. R. Gill, W. N. Hardy, R. S. Hayano, M. E. Hayden, A. J. Humphries, R. Hydomako, L. V. Jørgensen, S. J. Kerrigan, J. Keller, L. Kurchaninov, R. Lambo, N. Madsen, P. Nolan, K. Olchanski, A. Olin, 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

Control of the radial profile of trapped antiproton clouds is critical to trapping antihydrogen. We report the first detailed measurements of the radial manipulation of antiproton clouds, including areal density compressions by factors as large as ten, by manipulating spatially overlapped electron plasmas. [...]

G. B. Andresen, W. Bertsche, P. D. Bowe, C. C. Bray, E. Butler, C. L. Cesar, 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, R. Hydomako, M. J. Jenkins, L. V. Jørgensen, L. Kurchaninov, R. Lambo, N. Madsen, P. Nolan, K. Olchanski, A. Olin, 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

We report results from a novel diagnostic that probes the outer radial profile of trapped antiproton clouds. The diagnostic allows us to determine the profile by monitoring the time history of antiproton losses that occur as an octupole field in the antiproton confinement region is increased. [...]
Published in

G. B. Andresen, W. Bertsche, P. D. Bowe, C. C. Bray, E. Butler, C. L. Cesar, 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

When particles in a Penning trap are subject to a magnetic multipole field, those beyond a critical radius will be lost. The critical radius depends on the history by which the field is applied, and can be much smaller if the particles are injected into a preexisting multipole than if the particles are subject to a ramped multipole. [...]
Published in

J. Fajans, N. Madsen, and F. Robicheaux

Refereed Publication
06 Mar 2008
The creation of atoms of antihydrogen under controlled conditions has opened up a new era in physics with antimatter. We describe the experimental realisation of low energy antihydrogen, via the mixing of carefully prepared clouds of positrons and antiprotons, and some of the progress that has been made in the last few years in characterising properties of the nascent anti-atoms. [...]
Published in

M. Charlton, S. Jonsell, L.V. Jørgensen, N. Madsen and D.P. van der Werf

We have demonstrated production of antihydrogen in a 1 T solenoidal magnetic field. This field strength is significantly smaller than that used in the first generation experiments ATHENA (3 T) and ATRAP (5 T). The motivation for using a smaller magnetic field is to facilitate trapping of antihydrogen atoms in a neutral atom trap surrounding the production region. [...]
Published in

G. B. Andresen, W. Bertsche, A. Boston, P. D. Bowe, C. L. Cesar, S. Chapman, M. Charlton, M. Chartier, A. Deutsch, J. Fajans, M. C. Fujiwara, R. Funakoshi, D. R. Gill, K. Gomberoff, J. S. Hangst, R. S. Hayano, R. Hydomako, M. J. Jenkins, L.V. Jørgensen, L. Kurchaninov, N. Madsen, P. Nolan, K. Olchanski, A. Olin, 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

We have demonstrated storage of plasmas of the charged constituents of the antihydrogen atom, antiprotons and positrons, in a Penning trap surrounded by a minimum-B magnetic trap designed for holding neutral antiatoms. The neutral trap comprises a superconducting octupole and two superconducting, solenoidal mirror coils. [...]

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

Refereed Publication
02 Aug 2006
The goal of the ALPHA collaboration at CERN is to test CPT conservation by comparing the 1S–2S transitions of hydrogen and antihydrogen. To reach the ultimate accuracy of 1 part in 1018 , the (anti)atoms must be trapped. Using current technology, only magnetic minimum traps can confine (anti)hydrogen. [...]

W. Bertsche, A. Boston, P.D. Bowe, C.L. Cesar, S. Chapman, M. Charlton, M. Chartier, A. Deutsch, J. Fajans, M.C. Fujiwara, R. Funakoshi, K.Gomberoff, J.S. Hangst, R.S. Hayano, M. J. Jenkins, L. V. Jørgensen, P. Ko, N. Madsen, P. Nolan, R.D. Page, L.G.C. Posada, A. Povilus, E. Sarid, D. M. Silveira, D.P. van der Werf, Y. Yamazaki, B. Parker, J. Escallier, and A. Ghosh

Measurements on electrons confined in a Penning trap show that extreme quadrupole fields destroy particle confinement. Much of the particle loss comes from the hitherto unrecognized ballistic transport of particles directly into the wall. [...]

J. Fajans, W. Bertsche, K. Burke, S.F. Chapman and D.P van der Werf

Refereed Publication
01 Jan 2005
Plentiful quantities of antihydrogen, the bound state system of the antiparticles the positron and the antiproton, have recently been made under very controlled conditions in experiments at the European Laboratory of Particle Physics (CERN) near Geneva. [...]
Published in

Mike Charlton

Unrefereed Publication

Unrefereed Publication
23 Feb 2011

The ALPHA collaboration has achieved one of the long-stated goals of the physics programme at CERN’s Antiproton Decelerator: magnetic trapping of antihydrogen atoms.

Published in

Jeffrey Scott Hangst

Unrefereed Publication
01 Jun 2008
「水素原子がすっかり分かってしまったら,物理全体がす っかり分かってしまったのも同然だ」と [...]
Unrefereed Publication
18 Jul 2007

Antimatter is difficult to make, let alone store. Jeffrey Hangst describes how ALPHA, an experiment attempting to trap antihydrogen at CERN, overcomes some of the difficulties and he questions the reality of ever making more than the tiniest amounts of antimatter.

Published in

Jeffrey Scott Hangst

Unrefereed Publication
01 Jan 2006

I efteråret 2002 lykkedes det for første gang forskere at fremstille koldt antistof i form af antibrint-atomer. Nu vil forskerne så forsøge at fange disse antiatomer. Men hvordan fanger man noget, der tilintetgøres så snart det kommer i kontakt med almindeligt stof?

Niels Madsen

Unrefereed Publication
22 Oct 2005

Half a century since the discovery of the antiproton, and more than 70 years since that of the positron, researchers at CERN can routinely produce millions of antihydrogen atoms. Mike Charlton and Jeffrey Hangst explain how these remarkable anti-atoms could be our best bet for understanding one of the most fundamental symmetries of nature.

Published in

Mike Charlton, and Jeffrey Scott Hangst

Conference Proceeding (refereed)

Conference Proceeding (refereed)
01 Sep 2018
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. [...]

Andrea Capra for the ALPHA Collaboration

Conference Proceeding (refereed)
12 Mar 2018

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.

Andrea Capra & ALPHA Collaboration

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. [...]

William Bertsche

Conference Proceeding (refereed)
20 Feb 2018
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. [...]

Stefan Eriksson

Conference Proceeding (refereed)
20 Feb 2018
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. [...]

Niels Madsen

Conference Proceeding (refereed)
15 Oct 2016
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. [...]
Published in

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

Conference Proceeding (refereed)
21 Dec 2013
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. [...]

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

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. [...]

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.

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. [...]

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.

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. [...]
Published in

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.

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. [...]
Published in

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

Conference Proceeding (refereed)
08 Dec 2011
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. [...]
Published in

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

Conference Proceeding (refereed)
05 Nov 2011
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. [...]
Published in

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

Conference Proceeding (refereed)
04 Jun 2011
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. [...]
Published in

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.

Conference Proceeding (refereed)
01 Jan 2011
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. [...]

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

Conference Proceeding (refereed)
01 Jan 2009
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. [...]

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

Conference Proceeding (refereed)
15 Dec 2007
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. [...]

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

Conference Proceeding (refereed)
01 Jan 2007
ALPHA is an international project that has recently begun experimentation at CERN’s Antiproton Decelerator (AD) facility. [...]
Published in

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

Conference Proceeding (unrefereed)

Conference Proceeding (unrefereed)
11 Jan 2012
ALPHA is one of the experiments situated at CERN's Antiproton Decelerator (AD). A Silicon Vertex Detector (SVD) is placed to surround the ALPHA atom trap. [...]
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G. B. Andresen, M. D. Ashkezari, 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, M. J. Jenkins, S. Jonsell, L. V. JØrgensen, L. Kurchaninov, N. Madsen, J. T. K. McKenna, S. Menary, P. Nolan, K. Olchanski, A. Olin, A. Povilus, P. Pusa, F. Robicheaux, J. Sampson, E. Sarid, D. Seddon, S. Seif el Nasr, D. M. Silveira, C. So, J. W. Storey, R. I. Thompson, J. Thornhill, D. Wells, D. P. van der Werf

Conference Proceeding (unrefereed)
15 Nov 2010
ALPHA is an experiment at CERN, whose ultimate goal is to perform a precise test of CPT symmetry with trapped antihydrogen atoms. [...]

M.C. Fujiwara, G.B. Andresen, M.D. Ashkezari, M. Baquero-Ruiz, W. Bertsche, C.C. Bray, E. Butler, C.L. Cesar, S. Chapman, M. Charlton, C.L. Cesar, J. Fajans, T. Friesen, D.R. Gill J.S. Hangst, W.N. Hardy, R.S. Hayano, M.E. Hayden, A.J. Humphries, R. Hydomako, S. Jonsell, L. Kurchaninov, R. Lambo, 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, D. Wilding, J.S. Wurtele, and Y. Yamazaki

Conference Proceeding (unrefereed)
03 Sep 2008
Control of the radial profile of trapped antiproton clouds is critical to trapping antihydrogen. We report detailed measurements of the radial manipulation of antiproton clouds, including areal density compressions by factors as large as ten, achieved by manipulating spatially overlapped electron plasmas. [...]

G.B. Andresen, W. Bertsche, P.D. Bowe, C.C. Bray, E. Butler, C.L. Cesar, 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

Conference Proceeding (unrefereed)
01 Sep 2008
We discuss aspects of antihydrogen studies, that relate to particle physics ideas and techniques, within the context of the ALPHA experiment at CERN’s Antiproton Decelerator facility. We review the fundamental physics motivations for antihydrogen studies, and their potential physics reach. [...]

M.C. Fujiwara, G. B. Andresen, W. Bertsche, P.D. Bowe, C.C. Bray, E. Butler, C. L. Cesar, S. Chapman, M. Charlton, J. Fajans, 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, W. Lai, R. Lambo, N. Madsen, P. Nolan, K. Olchanski, A. Olin, 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, L. Wasilenko, J.S. Wurtele, and Y. Yamazaki

Conference Proceeding (unrefereed)
31 Aug 2008
The ALPHA apparatus is designed to produce and trap antihydrogen atoms. The device comprises a multifunction Penning trap and a superconducting, neutral atom trap having a minimum-B configuration. [...]

G.B. Andresen, W. Bertsche, P.D. Bowe, C.C. Bray, E. Butler, C.L. Cesar, 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 derWerf, J.S. Wurtele and Y. Yamazaki

Conference Proceeding (unrefereed)
01 Aug 2007
ALPHA is a new experiment at the CERN Antiproton Decelerator (AD). The short term goal of ALPHA is trapping of cold antihydrogen, with the long term goal of conducting precise spectroscopic comparisons of hydrogen and antihydrogen. [...]

N. Madsen, G. Andresen, W. Bertsche, A. Boston, P.D. Bowe, E. Butler, C.L. Cesar, 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, R. Hydomako, M.J. Jenkins, L.V. Jørgensen, L. Kurchaninov, P. Nolan, K. Olchanski, A. Olin, A. Povilus, 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

Simple scaling laws strongly suggest that for antihydrogen relevant parameters, quadrupole magnetic fields will transport particles into, or near to, the trap walls. [...]

J. Fajans, W. Bertsche, K. Burke, A. Deutsch, S. F. Chapman, K. Gomberoff, D. P. van der Werf, and J. S. Wurtele

Conference Proceeding (unrefereed)
01 Jan 2006
The merging of antiprotons with a positron plasma is the predominant and highest efficient method for cold antihydrogen formation used to date [1, 2, 3]. We present experimental evidence that this method has serious disadvantages for producing antihydrogen cold enough to be trapped [4, 5]. Antihydrogen is neutral but may be trapped in a magnetic field minimum. [...]

Niels Madsen

Conference Proceeding (unrefereed)
01 Jan 2005
The ALPHA experiment aims to trap antihydrogen as the next crucial step towards a precise CPT test, by a spectroscopic comparison of antihydrogen with hydrogen. The experiment will retain the salient techniques developed by the ATHENA collaboration during the previous phase of antihydrogen experiments at the antiproton decelerator (AD) at CERN. [...]

W. Bertsche, A. Boston, P.D. Bowe, C.L. Cesar, S. Chapman, M. Charlton, M. Chartier, A. Deutsch, J. Fajans, M.C. Fujiwara, R. Funakoshi, D.Gill, K.Gomberoff, D. Grote , J.S. Hangst, R.S. Hayano, M. Jenkins, L. V. Jørgensen, N. Madsen, D. Miranda, P. Nolan, K. Ochanski, A.Olin, R.D. Page, L.G.C. Posada, F. Robicheaux, E. Sarid, H.H. Telle, J.-L. Vay, J. Wurtele, D.P. van der Werf, and Y. Yamazaki

Theses

One of the greatest problems facing modern physics is the apparent asymmetry between matter and antimatter. While the standard model of particle physics predicts that equal amounts of matter and antimatter were produced following the Big Bang, astronomical observations have revealed that our universe contains little or no primordial antimatter. Precision measurements of cold, trapped antiparticles can be used to probe fundamental symmetries, and may shed light on why antimatter is so scarce in our universe. The ALPHA experiment at the CERN Antiproton Decelerator studies magnetically trapped antihydrogen atoms, produced by slowly merging cold plasmas of positrons (e +) and antiprotons (¯p). The precision spectroscopy of antihydrogen has already provided unique, high-resolution tests of CPT invariance and theories of new physics beyond the standard model. During 2018, the ALPHA experiment was expanded with the addition of ALPHA-g, a vertical atom trap that is intended to make the first direct measurements of antimatter gravitation. [...]

Mark A. Johnson

A new technique for rapidly generating a sequence of target plasmas in a Penning-Malmberg trap is presented and applied in the first demonstration of cavity-resonant cooling in a plasma. This "reservoir'' technique further enables the in situ magnetic field to be measured to high precision by microwave ECR spectroscopy. A precision antihydrogen gravity experiment being constructed at CERN will rely on this method, as there is no other method with comparable absolute, spatial, and temporal resolution which can be implemented in the Penning-Malmberg trap. These cavity and microwave measurements require accessing new regimes with the plasma parallel energy analyzer, to which end the sensitivity of the latter technique has been increased twenty-fold.

Eric Hunter

The ALPHA (Antihydrogen Laser Physics Apparatus) collaboration creates and performs precise measurements on antihydrogen to test Charge-Parity-Time (CPT) symmetry. Prior to creating antihydrogen we must prepare the antiproton and positron plasmas to have optimal and repeatable parameters. This thesis presents the development of a new method to simultaneously control the number of particles and plasma density of lepton plasmas, developments that increased our antihydrogen trapping rate, precision physics measurements performed on antihydrogen, and other plasma studies still under development. The method to stabilize the number of particles was based on a zero-temperature plasma model, which states that the plasma's on-axis self potential and density uniquely define a plasma. [...]

Celeste Carruth

Our current understanding of physics suggests that matter and antimatter should be created and destroyed in equal amounts, but this seems inconsistent with the observation that our universe consists almost entirely of matter. Comparisons between matter and antimatter could reveal new physics which explains why the universe has formed with this apparent imbalance. The 1S-2S transition of hydrogen has been measured with incredible precision, and a similarly precise measurement of the 1S-2S transition of antihydrogen would constitute one of the best comparisons between matter and antimatter.

Steven Armstrong Jones

One of the best ways to study antimatter is to investigate antihydrogen, the bound state of an antiproton and a positron. Antihydrogen atoms do not exist naturally and must be synthesized in the lab by merging carefully-prepared plasmas of positrons and antiprotons. If the atoms are created in a magnetic trap like the one used by the ALPHA experiment at CERN, then a fraction of the coldest atoms remain trapped, while the rest escape and annihilate on the trap walls. The trapped atoms may then be probed using microwaves or lasers to make high-precision comparisons with hydrogen.
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Muhammed Sameed

Antihydrogen is the simplest pure antimatter atomic system, and it allows for direct tests of CPT symmetry as well as the weak equivalence principle. Furthermore, the study of antihydrogen may provide clues to the matter- antimatter asymmetry observed in the universe - one of the major unanswered questions in modern physics. Since 2010, it has been possible to perform such tests on magnetically trapped antihydrogen, and this work reports on several recent studies.

Chris Ørum Rasmussen

Antihydrogen is the simplest neutral antimatter atom. Precision comparisons between hydrogen and antihydrogen would provide stringent tests of CPT (charge conjugation/parity transformation/time reversal) invariance and the weak equivalence principle. In the last few years, the ALPHA collaboration has produced, and trapped antihydrogen [1, 2]. Most recently, this collaboration has probed antihydrogen’s internal structure by inducing hyperfine transitions in ground state atoms [3]. In this thesis, many details of the cold antihydrogen formation, trapping and measurements of antihydrogen performed in the ALPHA apparatus are presented, with a focus on antiproton cloud compression. Such compression is an important tool for the formation and trapping of cold antihydrogen, since it allows control of the radial size and density of the antiproton cloud. Compression of non-neutral plasmas can be achieved using a rotating time-varying azimuthal electric field, which has been called rotating wall technique.
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Andrea Gutierrez

High precision antihydrogen experiments allow tests of fundamental theoretical descriptions of nature. These experiments are performed with the ALPHA apparatus, where ultra-low energy antihydrogen is produced and confined in a magnetic trap. Antihydrogen spectroscopy is of primary interest for precision tests of CPT invariance - one of the most important symmetries of the Standard Model. [...]

Andrea Capra

The asymmetry between matter and antimatter in the universe and the incompatibility between the Standard Model and general relativity are some of the greatest unsolved questions in physics. The answer to both may possibly lie with the physics beyond the Standard Model, and comparing the properties of hydrogen and antihydrogen atoms provides one of the possible ways to exploring it. In 2010, the ALPHA collaboration demonstrated the first trapping of antihydrogen atoms, in an apparatus made of a Penning–Malmberg trap superimposed on a magnetic minimum trap. Its ultimate goal is to precisely measure the spectrum, gravitational mass and charge neutrality of the anti-atoms, and compare them with the hydrogen atom. These comparisons provide novel, direct and model–independent tests of the Standard Model and the weak equivalence principle. Before they can be achieved, however, the trapping rate of antihydrogen atoms needs to be improved. [...]

Chukman So

The recent demonstration of trapping of antihydrogen atoms by the ALPHA collaboration at CERN opened great possibilities to study antimatter and perform precision measurements on it. In this work, a retrospective analysis of the 2010 and 2011 experimental runs in ALPHA, together with comprehensive studies of the apparatus and detailed simulations of the manipulations of anti-atoms, are performed and used to measure the electric charge of antihydrogen. This result is an example of a precision measurement on antimatter that may ultimately lead to keys for solving some of the most important problems in physics today, such as the asymmetry between matter and antimatter, by comparison to measurements carried out on “normal” matter atoms. [...]

Marcelo Baquero-Ruiz

We have every reason to believe that equal amounts of matter and antimatter were produced in the early universe. Moreover, theory predicts that the laws of physics make no distinction between the two. In this light, the fact that the observable universe is overwhelmingly dominated by matter is inexplicable. ALPHA is an international project located at CERN involving approximately 40 physicists from 15 different institutions in 7 countries. The primary goal of the collaboration is to study the antihydrogen atom at the highest level of precision possible, and thereby enable comparisons between hydrogen and antihydrogen. Through these comparisons it hopes to improve our understanding of the distinction between matter and antimatter, and perhaps shed some light on the puzzle of why we live in a matter dominated universe. The hyperfine energy intervals of ground-state hydrogen and antihydrogen represent an opportunity for a precision comparison. A discrepancy between the energy levels of these two atomic systems would indicate a major revolution in physics, and in our understanding of the universe. [...]

Mohammad Dehghani Ashkezari

Antihydrogen, the bound state of a positron and an antiproton, is the simplest pure anti-atomic system and an excellent candidate to test the symmetry between matter and antimatter. This thesis focuses on the magnetic confinement of antihydrogen and the first ever resonant interaction with trapped antihydrogen, as performed by the ALPHA collaboration. The ALPHA apparatus and the techniques that have been developed to form, trap, probe, and detect antihydrogen atoms will be described in detail. The first successful demonstration of trapped antihydrogen will then be described. In the initial demonstrations, 38 trapped antihydrogen atoms were detected after being confined for at least 172 ms. Since then, over 400 antihydrogen atoms have been trapped and confinement times of 1000 s (over 15 minutes) have been demonstrated. Spectroscopy of these trapped antihydrogen atoms is the next major step forward. As an initial proof-of-principle demonstration, ALPHA induced and observed resonant positron spin flip (PSR) transitions between the ground states of antihydrogen. [...]

Timothy Peter Friesen

The ALPHA experiment is an international effort to produce, trap, and perform precision spectroscopic measurements on antihydrogen (the bound state of a positron and an antiproton). Based at the Antiproton Decelerator (AD) facility at CERN, the ALPHA experiment has recently magnetically confined antihydrogen atoms for the first time. A crucial element in the observation of trapped antihydrogen is ALPHA’s silicon vertexing detector. This detector contains sixty silicon modules arranged in three concentric layers, and is able to determine the three-dimensional location of the annihilation of an antihydrogen atom by reconstructing the trajectories of the produced annihilation products. [...]

Richard A. Hydomako

One proposed technique for trapping anti-atoms is to superimpose a Ioffe-Pritchard style magnetic-minimum neutral trap on a standard Penning trap used to trap the charged atomic constituents. Adding a magnetic multipole field in this way removes the azimuthal symmetry of the ideal Penning trap and introduces a new avenue for radial diffusion. Enhanced diffusion will lead to increased Joule heating of a non-neutral plasma, potentially adversely affecting the formation rate of anti-atoms and increasing the required trap depth. We present a model of this effect, along with an approach to minimizing it, with comparison to measurements from an intended anti-atom trap.

Steven Francis Chapman

Antihydrogen, the simplest pure-antimatter atomic system, holds the promise of direct tests of matter-antimatter equivalence and CPT invariance, two of the outstanding unanswered questions in modern physics. Antihydrogen is now routinely produced in charged-particle traps through the combination of plasmas of antiprotons and positrons, but the atoms escape and are destroyed in a minuscule fraction of a second. The focus of this work is the production of a sample of cold antihydrogen atoms in a magnetic atom trap. This poses an extreme challenge, because the state-of-the-art atom traps are only approximately 0.5 K deep for ground-state antihydrogen atoms, much shallower than the energies of particles stored in the plasmas. [...]

Eoin Butler

Evaporative cooling has proven to be an invaluable technique in atomic physics, allowing for the study of effects such as Bose-Einstein condensation. One main topic of this thesis is the first application of evaporative cooling to cold non-neutral plasmas stored in an ion trap. We (the ALPHA collaboration) have achieved cooling of a cloud of antiprotons to a temperature as low as 9 K, two orders of magnitude lowerthan ever directly measured previously. The measurements are well-described by appropriate rate equations for the temperature and number of particles. The technique has direct application to the ongoing attempts to produce trapped samples of antihydrogen. In these experiments the maximum trap depths are ex tremely shallow (~0.6 K for ground state atoms), and careful control of the trapped antiprotons and positrons used to form the (anti)atoms is essential to succes. Since 2006 powerful tools to diagnose and manipulate the antiproton and positron plasmas in the ALPHA apparatus have been developed and used in attempts to trap antihydrogen. [...]

Gorm Bruun Andresen

This thesis details the development and commissioning of the ALPHA antihydrogen trapping apparatus. It discusses the history of antimatter physics that led to and enabled the design of the apparatus. It discusses the importance of antihydrogen trapping in testing one of the basic assumptions of the Standard Model of particle physics (that of CPT invariance). It goes on to discuss the design and construction of the apparatus. Finally, it presents results that demonstrate antihydrogen formation in the new magnetic field configurations that together constitute a magnetic minimum trap for neutral antihydrogen. This is an important preliminary result for any antihydrogen trapping apparatus, and confirms that the ALPHA apparatus does present a potential route towards laser spectroscopy of antihydrogen.

Matthew Jenkins

This thesis describes several models of antihydrogen formation as well as the commissioning of the ALPHA antihydrogen during the 2006 Antiproton Decelerator (AD) physics run. Three models are given to describe the short-time production of antihydrogen, including the Simple Temperature Dependant Model, Inverse Velocity Model, and Scaled Inverse Velocity Model. All three models are compared to results from the ATHENA experiment. After an introduction to the ALPHA apparatus and some of the techniques used to produce antihydrogen the commissioning process is described, focusing on the optimization of the antiproton capture, cooling, and manipulation. Also included is an appendix describing in detail the ALPHA data acquisition system as of the end of the 2006 physics run

Richard A. Hydomako