A novel antiproton radial diagnostic based on octupole induced ballistic loss

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

doi:10.1063/1.2899305

Cited by 9 publications

(5 citation statements)

References 26 publications

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“…A consequence of the non-cylindrically symmetric transverse magnetic field of the multipole is that it can disrupt the aforementioned charged particle confinement. In the most extreme case, particles residing outside a critical radius follow a magnetic field line that crosses an electrode surface over the length of an axial oscillation, and are immediately lost [90]. Even outside this regime, measurements on non-neutral plasmas stored in a quadrupole demonstrated an increased rate of diffusion in the transverse direction, thus reducing the storage time and possibly resulting in heating through the release of electrostatic potential energy [91].…”

Section: Magnetic Traps For Antihydrogenmentioning

confidence: 99%

Physics with antihydrogen

Bertsche

Butler

Charlton

et al. 2015

J. Phys. B: At. Mol. Opt. Phys.

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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. Once formed, the antihydrogen has been detected by its destruction via annihilation or field ionization, and aspects of the methodologies involved are summarized. Magnetic minimum neutral atom traps have been employed to allow some of the antihydrogen created to be held for considerable periods. We describe such devices, and their implementation, along with the cusp magnetic trap used to produce the first evidence for a low-energy beam of antihydrogen. The experiments performed to date on antihydrogen are discussed, including the first observation of a resonant quantum transition and the analyses that have yielded a limit on the electrical neutrality of the anti-atom and placed crude bounds on its gravitational behaviour. Our review concludes with an outlook, including the new ELENA extension to the antiproton decelerator facility at CERN, together with summaries of how we envisage the major threads of antihydrogen physics will progress in the coming years.

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Section: Magnetic Traps For Antihydrogenmentioning

confidence: 99%

Physics with antihydrogen

Bertsche

Butler

Charlton

et al. 2015

J. Phys. B: At. Mol. Opt. Phys.

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“…[4][5][6][7] In this paper, the ALPHA collaboration reports on the relative and absolute sensitivity of the MCP to leptons and p's and shows how the diagnostic can be used to find the line-integrated radial density profiles of the particles in our Penning-Malmberg trap. The goal of the ALPHA collaboration is to synthesize, trap, and study antihydrogen.…”

Section: Introductionmentioning

confidence: 99%

Antiproton, positron, and electron imaging with a microchannel plate/phosphor detector

Andresen

Bertsche

Bowe

et al. 2009

Review of Scientific Instruments

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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. The response of the MCP to low energy (10-200 eV, <1 eV spread) antiproton extractions is compared to that of electrons and positrons.

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“…To minimize the influence of these fields on the charged particles used forH formation, we use an octupole to provide the transverse minimum-B, rather than a quadrupole as in the prototypical Ioffe-Pritchard geometry [10]. In order to further reduce transverse-field effects we have developed techniques to characterize and reduce the radial extent of our various particle species [11,12].…”

mentioning

confidence: 99%

“…4 In the presence of the octupole, the axial vertex distribution can depend on thep radial density distribution because, as mentioned earlier, a Penning-trap with a superposed multipole field has, for a given axial excursion, a critical radius beyond which particles are lost [7]. We can use the octupole as a radial diagnostic and measure the radial distribution of thep by ramping up the octupole field whilst monitoringp annihilations [11]. In the experiments discussed in this article the smallest r crit for trapped particles is 9 mm.…”

mentioning

confidence: 99%

Antihydrogen formation dynamics in a multipolar neutral anti-atom trap

et al. 2010

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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. We further establish how field-ionization causes radial redistribution of the antiprotons during antihydrogen formation and use this effect for the first simultaneous measurements of strongly and weakly bound antihydrogen atoms. Distinguishing between these provides critical information needed in the process of optimizing for trappable antihydrogen. These observations are of crucial importance to the ultimate goal of performing CPT tests involving antihydrogen, which likely depends upon trapping the anti-atom

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A novel antiproton radial diagnostic based on octupole induced ballistic loss

Cited by 9 publications

References 26 publications

Physics with antihydrogen

Physics with antihydrogen

Antiproton, positron, and electron imaging with a microchannel plate/phosphor detector

Antihydrogen formation dynamics in a multipolar neutral anti-atom trap

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