Search

Your search keyword '"Thompson, R. I."' showing total 12 results
Start Over Author "Thompson, R. I." Publisher fysikum
12 results on '"Thompson, R. I."'

1. In situ electromagnetic field diagnostics with an electron plasma in a Penning-Malmberg trap

Author

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

Abstract

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. The cyclotron motion of the electron plasma is excited by microwave radiation and the temperature change of the plasma is measured non-destructively by monitoring the plasma's quadrupole mode frequency. The spatially resolved microwave electric field strength can be inferred from the plasma temperature change and the magnetic field is found through the cyclotron resonance frequency. These measurements were used extensively in the recently reported demonstration of resonant quantum interactions with antihydrogen., AuthorCount:40

Published
2014
Full Text
View/download PDF

2. The ALPHA antihydrogen trapping apparatus

Author

Amole, C., Andresen, G. B., Ashkezari, M. D., Baquero-Ruiz, M., Bertsche, W., Bowe, P. D., Butler, E., Capra, A., Carpenter, P. T., Cesar, C. L., Chapman, S., Charlton, M., Deller, A., Eriksson, S., Escallier, J., 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., Isaac, C. A., Jenkins, M. J., Jonsell, Svante, Jörgensen, L. V., Kerrigan, S. J., Kurchaninov, L., Madsen, N., Morone, A., McKenna, J. T. K., Menary, S., Nolan, P., Olchanski, K., Olin, A., Parker, B., Povilus, A., Pusa, P., Robicheaux, F., Sarid, E., Seddon, D., El Nasr, S. Seif, Silveira, D. M., So, C., Storey, J. W., Thompson, R. I., Thornhill, J., Wells, D., van der Werf, D. P., Wurtele, J. S., Yamazaki, Y., Amole, C., Andresen, G. B., Ashkezari, M. D., Baquero-Ruiz, M., Bertsche, W., Bowe, P. D., Butler, E., Capra, A., Carpenter, P. T., Cesar, C. L., Chapman, S., Charlton, M., Deller, A., Eriksson, S., Escallier, J., 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., Isaac, C. A., Jenkins, M. J., Jonsell, Svante, Jörgensen, L. V., Kerrigan, S. J., Kurchaninov, L., Madsen, N., Morone, A., McKenna, J. T. K., Menary, S., Nolan, P., Olchanski, K., Olin, A., Parker, B., Povilus, A., Pusa, P., Robicheaux, F., Sarid, E., Seddon, D., El Nasr, S. Seif, Silveira, D. M., So, C., Storey, J. W., Thompson, R. I., Thornhill, J., Wells, D., van der Werf, D. P., Wurtele, J. S., and Yamazaki, Y.

Abstract

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. The ALPHA apparatus will be described herein, with emphasis on the structural aspects, diagnostic methods and techniques that have enabled antihydrogen trapping and experimentation to be achieved., AuthorCount:56

Published
2014
Full Text
View/download PDF

3. 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
Full Text
View/download PDF

4. The ALPHA-detector : Module Production and Assembly

Author

Andresen, G. B., Ashkezari, M. D., Baquero-Ruiz, M., Bertsche, W., Bowe, P. D., Butler, E., 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., Hydomako, R., Jenkins, M. J., Jonsell, Svante, Jorgensen, L. V., Kurchaninov, L., Madsen, N., McKenna, J. T. K., Menary, S., Nolan, P., Olchanski, K., Olin, A., Povilus, A., Pusa, P., Robicheaux, F., Sampson, J., Sarid, E., Seddon, D., el Nasr, S. Seif, Silveira, D. M., So, C., Storey, J. W., Thompson, R. I., Thornhill, J., Wells, D., van der Werf, D. P., Wurtele, J. S., Yamazaki, Y., Andresen, G. B., Ashkezari, M. D., Baquero-Ruiz, M., Bertsche, W., Bowe, P. D., Butler, E., 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., Hydomako, R., Jenkins, M. J., Jonsell, Svante, Jorgensen, L. V., Kurchaninov, L., Madsen, N., McKenna, J. T. K., Menary, S., Nolan, P., Olchanski, K., Olin, A., Povilus, A., Pusa, P., Robicheaux, F., Sampson, J., Sarid, E., Seddon, D., el Nasr, S. Seif, Silveira, D. M., So, C., Storey, J. W., Thompson, R. I., Thornhill, J., Wells, D., van der Werf, D. P., Wurtele, J. S., and Yamazaki, Y.

Abstract

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. The main purpose of the SVD is to detect and locate antiproton annihilation events by means of the emitted charged pions. The SVD system is presented with special focus given to the design, fabrication and performance of the modules., AuthorCount:47

Published
2012
Full Text
View/download PDF

5. Discriminating between antihydrogen and mirror-trapped antiprotons in a minimum-B trap

Author

Amole, C., Andresen, G. B., Ashkezari, M. D., Baquero-Ruiz, M., Bertsche, W., Butler, E., 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., Hydomako, R., Kurchaninov, L., Jonsell, Svante, 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., Wurtele, J. S., Amole, C., Andresen, G. B., Ashkezari, M. D., Baquero-Ruiz, M., Bertsche, W., Butler, E., 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., Hydomako, R., Kurchaninov, L., Jonsell, Svante, 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., and Wurtele, J. S.

Abstract

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. The antiproton annihilations produce easily detected signals; we used these signals to prove that we trapped antihydrogen. However, our technique could be confounded by mirror-trapped antiprotons, which would produce seemingly identical annihilation signals upon hitting the trap wall. In this paper, we discuss possible sources of mirror-trapped antiprotons and show that antihydrogen and antiprotons can be readily distinguished, often with the aid of applied electric fields, by analyzing the annihilation locations and times. We further discuss the general properties of antiproton and antihydrogen trajectories in this magnetic geometry, and reconstruct the antihydrogen energy distribution from the measured annihilation time history., 38

Published
2012
Full Text
View/download PDF

6. Search for trapped antihydrogen

Author

Andresen, G. B., Ashkezari, M. D., Baquero-Ruiz, M., Bertsche, W., Bowe, P. D., Bray, C. C., 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., Hayano, R. S., Hayden, M. E., Humphries, A. J., Hydomako, R., Jonsell, Svante, Jörgensen, L. V., Kurchaninov, L., Lambo, R., Madsen, N., Menary, S., Nolan, P., Olchanski, K., Olin, A., Povilus, A., Pusa, P., Robicheaux, F., Sarid, E., Seif El Nasr, S., Silveira, D. M., So, C., Storey, J. W., Thompson, R. I., van der Werf, D. P., Wilding, D., Wurtele, J. S., Yamazaki, Y., Andresen, G. B., Ashkezari, M. D., Baquero-Ruiz, M., Bertsche, W., Bowe, P. D., Bray, C. C., 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., Hayano, R. S., Hayden, M. E., Humphries, A. J., Hydomako, R., Jonsell, Svante, Jörgensen, L. V., Kurchaninov, L., Lambo, R., Madsen, N., Menary, S., Nolan, P., Olchanski, K., Olin, A., Povilus, A., Pusa, P., Robicheaux, F., Sarid, E., Seif El Nasr, S., Silveira, D. M., So, C., Storey, J. W., Thompson, R. I., van der Werf, D. P., Wilding, D., Wurtele, J. S., and Yamazaki, Y.

Abstract

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. The use of a position-sensitive annihilation vertex detector, together with the capability of controllably quenching the superconducting magnetic minimum trap, enabled us to carry out a high-sensitivity and low-background search for trapped synthesised antihydrogen atoms. We aim to identify the annihilations of antihydrogen atoms held for at least 130 ms in the trap before being released over ~30 ms. After a three-week experimental run in 2009 involving mixing of 107 antiprotons with 1.3ￜ109 positrons to produce 6ￜ105 antihydrogen atoms, we have identified six antiproton annihilation events that are consistent with the release of trapped antihydrogen. The cosmic ray background, estimated to contribute 0.14 counts, is incompatible with this observation at a significance of 5.6 sigma. Extensive simulations predict that an alternative source of annihilations, the escape of mirror-trapped antiprotons, is highly unlikely, though this possibility has not yet been ruled out experimentally.

Published
2011
Full Text
View/download PDF

7. Antiparticle sources for antihydrogen production and trapping

Author

Charlton, M, Andresen, G B, Ashkezari, M D, Baquero-Ruiz, M, Bertsche, W, Bowe, P D, Bray, C C, Butler, E, Cesar, C L, Chapman, S, 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, Svante, JÞrgensen, L V, Kerrigan, S J, Kurchaninov, L, Lambo, R, Madsen, N, Menary, S, Nolan, P, Olchanski, K, Povilus, A, Pusa, P, Robicheaux, F, Sarid, E, Nasr, S Seif El, Silveira, D M, So, C, Storey, J W, Thompson, R I, Werf, D P Van Der, Wilding, D, Wurtele, J S, Yamazaki, Y, Collaboration, Alpha, Charlton, M, Andresen, G B, Ashkezari, M D, Baquero-Ruiz, M, Bertsche, W, Bowe, P D, Bray, C C, Butler, E, Cesar, C L, Chapman, S, 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, Svante, JÞrgensen, L V, Kerrigan, S J, Kurchaninov, L, Lambo, R, Madsen, N, Menary, S, Nolan, P, Olchanski, K, Povilus, A, Pusa, P, Robicheaux, F, Sarid, E, Nasr, S Seif El, Silveira, D M, So, C, Storey, J W, Thompson, R I, Werf, D P Van Der, Wilding, D, Wurtele, J S, Yamazaki, Y, and Collaboration, Alpha

Abstract

Sources of positrons and antiprotons that are currently used for the formation of antihydrogen with low kinetic energies are reviewed, mostly in the context of the ALPHA collaboration and its predecessor ATHENA. The experiments were undertaken at the Antiproton Decelerator facility, which is located at CERN. Operations performed on the clouds of antiparticles to facilitate their mixing to produce antihydrogen are described. These include accumulation, cooling and manipulation. The formation of antihydrogen and some of the characteristics of the anti-atoms that are created are discussed. Prospects for trapping antihydrogen in a magnetic minimum trap, as envisaged by the ALPHA collaboration, are reviewed.

Published
2011
Full Text
View/download PDF

8. Confinement of antihydrogen for 1,000 seconds

Author

Andresen, G. B., Ashkezari, M. D., Baquero-Ruiz, M., Bertsche, W., Bowe, P. D., Butler, E., Cesar, C. L., Charlton, M., Deller, A., 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., Hydomako, R., Jonsell, Svante, Kemp, S. L., Kurchaninov, L., Madsen, N., Menary, S., Nolan, P., Olchanski, K., Olin, A., Pusa, P., Rasmussen, C. O., Robicheaux, F., Sarid, E., Silveira, D. M., So, C., Storey, J. W., Thompson, R. I., van der Werf, D. P., Wurtele, J. S., Yamazaki, Y., Andresen, G. B., Ashkezari, M. D., Baquero-Ruiz, M., Bertsche, W., Bowe, P. D., Butler, E., Cesar, C. L., Charlton, M., Deller, A., 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., Hydomako, R., Jonsell, Svante, Kemp, S. L., Kurchaninov, L., Madsen, N., Menary, S., Nolan, P., Olchanski, K., Olin, A., Pusa, P., Rasmussen, C. O., Robicheaux, F., Sarid, E., Silveira, D. M., So, C., Storey, J. W., Thompson, R. I., van der Werf, D. P., Wurtele, J. S., and Yamazaki, Y.

Abstract

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? Here, we report the observation of anti-atom confinement for 1,000 s, extending our earlier results by nearly four orders of magnitude. Our calculations indicate that most of the trapped anti-atoms reach the ground state. Further, we report the first measurement of the energy distribution of trapped antihydrogen, which, coupled with detailed comparisons with simulations, provides a key tool for the systematic investigation of trapping dynamics. These advances open up a range of experimental possibilities, including precision studies of charge-parity-time reversal symmetry and cooling to temperatures where gravitational effects could become apparent., authorCount :40

Published
2011
Full Text
View/download PDF

9. Autoresonant Excitation of Antiproton Plasmas

Author

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

Abstract

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. In contrast, only a fraction of the antiprotons in a warm plasma can be similarly excited. Antihydrogen was produced and trapped by using this technique to drive antiprotons into a positron plasma, thereby initiating atomic recombination, authorCount :37

Published
2011
Full Text
View/download PDF

10. Search for trapped antihydrogen in ALPHA

Author

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

Abstract

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. The ALPHA collaboration is therefore pursuing a path towards trapping cold antihydrogen to permit the use of precision atomic physics tools to carry out comparisons of antihydrogen and hydrogen. ALPHA has addressed these challenges. Control of the plasma sizes has helped to lower the influence of the multipole field used in the neutral atom trap, and thus lowered the temperature of the created atoms. Finally, the first systematic attempt to identify trapped antihydrogen in our system is discussed. This discussion includes special techniques for fast release of the trapped anti-atoms, as well as a silicon vertex detector to identify antiproton annihilations. The silicon detector reduces the background of annihilations, including background from antiprotons that can be mirror trapped in the fields of the neutral atom trap. A description of how to differentiate between these events and those resulting from trapped antihydrogen atoms is also included.

Published
2011
Full Text
View/download PDF

11. Trapped antihydrogen

Author

Andresen, G. B., Ashkezari, M. D., Baquero-Ruiz, M., Bertsche, W., Bowe, P. D., Butler, E., 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., Hydomako, R., Jenkins, M. J., Jonsell, Svante, Jorgensen, L. V., Kurchaninov, L., Madsen, N., Menary, S., Nolan, P., Olchanski, K., Olin, A., Povilus, A., Pusa, P., Robicheaux, F., Sarid, E., Nasr, S. Seif el, Silveira, D. M., So, C., Storey, J. W., Thompson, R. I., van der Werf, D. P., Wurtele, J. S., Yamazaki, Y., Andresen, G. B., Ashkezari, M. D., Baquero-Ruiz, M., Bertsche, W., Bowe, P. D., Butler, E., 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., Hydomako, R., Jenkins, M. J., Jonsell, Svante, Jorgensen, L. V., Kurchaninov, L., Madsen, N., Menary, S., Nolan, P., Olchanski, K., Olin, A., Povilus, A., Pusa, P., Robicheaux, F., Sarid, E., Nasr, S. Seif el, Silveira, D. M., So, C., Storey, J. W., Thompson, R. I., van der Werf, D. P., Wurtele, J. S., and Yamazaki, Y.

Abstract

Antimatter was first predicted1 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 produced2, 3 at low energies at CERN (the European Organization for Nuclear Research) since 2002. Antihydrogen is of interest for use in a precision test of nature’s fundamental symmetries. The charge conjugation/parity/time reversal (CPT) theorem, a crucial part of the foundation of the standard model of elementary particles and interactions, demands that hydrogen and antihydrogen have the same spectrum. Given the current experimental precision of measurements on the hydrogen atom (about two parts in 1014 for the frequency of the 1s-to-2s transition4), subjecting antihydrogen to rigorous spectroscopic examination would constitute a compelling, model-independent test of CPT. Antihydrogen could also be used to study the gravitational behaviour of antimatter5. However, so far experiments have produced antihydrogen that is not confined, precluding detailed study of its structure. Here we demonstrate trapping of antihydrogen atoms. From the interaction of about 107 antiprotons and 7 × 108 positrons, we observed 38 annihilation events consistent with the controlled release of trapped antihydrogen from our magnetic trap; the measured background is 1.4 ± 1.4 events. This result opens the door to precision measurements on anti-atoms, which can soon be subjected to the same techniques as developed for hydrogen.

Published
2010
Full Text
View/download PDF

12. Evaporative Cooling of Antiprotons to Cryogenic Temperatures

Author

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., Hayano, R. S., Hayden, M. E., Humphries, A., Hydomako, R., Jonsell, Svante, 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., 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., Hayano, R. S., Hayden, M. E., Humphries, A., Hydomako, R., Jonsell, Svante, 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., and Yamazaki, Y.

Abstract

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. The technique opens up new possibilities for cooling of trapped ions and is of particular interest in antiproton physics, where a precise CPT test on trapped antihydrogen is a long-standing goal.

Published
2010
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results