The ATHENA antihydrogen apparatus

Amoretti, M.; Amsler, C.; Bonomi, G.; Bouchta, A.; Bowe, P. D.; Carraro, C.; Charlton, M.; Collier, M. J. T.; Doser, M.; Filippini, V.; Fine, K. S.; Fontana, A.; Fujiwara, M.; Funakoshi, R.; Genova, P.; Glauser, Adrian M.; Grögler, Dominik; Hangst, J. S.; Hayano, R.; Higaki, Hidehiko; Holzscheiter, M. H.; Joffrain, Walter; Jørgensen, L. V.; Lagomarsino, V.; Landua, R.; Cesar, C. L.; Lindelöf, D.; Lodi-Rizzini, E.; Macrı́, M.; Madsen, N.; Manuzio, D.; Manuzio, G.; Marchesotti, M.; Montagna, P.; Pruys, H.; Regenfus, C.; Riedler, P.; Rochet, J.; Rotondi, A.; Rouleau, G.; Testera, G.; Werf, D. P. van der; Variola, A.; Watson, T.L.; Yamazaki, T.; Yamazaki, Y.

doi:10.1016/j.nima.2003.09.052

Cited by 78 publications

(52 citation statements)

References 57 publications

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“…The ATHENA apparatus, described extensively in [8], consisted of a multielectrode system of cylindrical Penning traps, 2.5 cm in diameter and ∼ 1 m in length kept in an axial magnetic field of 3 T. In the 15 K cryogenic environment of the trap, only hydrogen and helium were present in gaseous form, giving a residual pressure of ∼ 10 −12 Torr. Antiprotons from the AD were caught, cooled by electrons and stored in the so-called mixing trap.…”

Section: Methodsmentioning

confidence: 99%

Production of slow protonium in vacuum

Zurlo¹,

Rizzini²,

Venturelli³

et al. 2007

TCP 2006

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We describe how protonium, the quasi-stable antiproton-proton bound system, has been synthesized following the interaction of antiprotons with the molecular ion H + 2 in a nested Penning trap environment. From a careful analysis of the spatial distributions of antiproton annihilation events in the ATHENA experiment, evidence is presented for protonium production with sub-eV kinetic energies in states around n = 70, with low angular momenta. This work provides a new 2-body system for study using laser spectroscopic techniques.

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Section: Methodsmentioning

confidence: 99%

Production of slow protonium in vacuum

Zurlo¹,

Rizzini²,

Venturelli³

et al. 2007

TCP 2006

Self Cite

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“…Following ATHENA [18], ALPHA adopted a silicon vertex detector as the technology of choice for the detection of the charged products of the annihilation of the antihydrogen constituents with the surrounding matter environment. The presence of antihydrogen in the trap is signaled by a delayed antiproton annihilation signature following the intentional release of confined antihydrogen [19], accomplished by quickly lowering the walls of the magnetic trap (usually resulting in a quench of the magnets).…”

Section: Rf-induced Positron Spin Resonance Transitions In Trapped Anmentioning

confidence: 99%

Real-time Detection of Antihydrogen Annihilations and Applications to Spectroscopy

Stracka

2014

EPJ Web of Conferences

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Abstract. A detection scheme based on real-time measurement of antihydrogen annihilations during radiation injection is presented, which allows an efficient use of the trapped atoms for laser and microwave spectroscopy. The application of real-time detection of H annihilations to microwave spectroscopy, which yielded the first evidence of microwaveinduced spin-flip transitions in trapped antihydrogen [1], is reported.

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“…Indeed, the ATHENA antihydrogen detector contained an array of 192 CsI crystals used to detect the photons produced in positron annihilation [36,102]. However, this system had the disadvantage of a low photon detection efficiency (∼ 25% per CsI modules, or ∼ 5% total efficiency for the detection the two simultaneous photons [103]). …”

Section: Electron-positron Annihilationmentioning

confidence: 99%

“…This model indicates that 10 4 antiprotons, with initial energies in the keV range, can be cooled to the eV range in several hundred milliseconds using an electron cloud with a density of ∼ 10 8 cm −3 [103]. In the absence of any external heating, the electrons would cool to the ambient temperature (4.2 K liquid helium cryogenic bath), and the antiprotons would follow.…”

mentioning

confidence: 99%

Detection of Trapped Antihydrogen

Hydomako

2013

Springer Theses

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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.This dissertation focuses mainly on the methods used to reconstruct the annihilation location. Specifically, the software algorithms used to identify and extrapolate charged particle tracks are presented along with the routines used to estimate the annihilation location from the convergence of the identified tracks. It is shown that these methods can determine the annihilation location with a spatial resolution between about 0.6 to 0.8 cm (depending on the coordinate being measured). Furthermore, a robust analysis to identify and reduce cosmic ray background events is described. The cosmic ray background can obscure the trapped antihydrogen signal, and its suppression leads to a significant increase in the annihilation detection sensitivity. The background suppression analysis involves examining the reconstructed detector event based on several selection criteria, including: the number of charged particle tracks, the radial vertex position, and a fit of a straight line to the event hit positions. By carefully optimizing these criteria, (99.54 ± 0.02)% of cosmic ray events are rejected, while (64.4 ± 0.1)% of antihydrogen annihilation events are retained. Finally, the experimental results demonstrating the first-ever magnetic confinement of antihydrogen atoms are presented. These results rely heavily on the silicon i detector, and as such, the role of the annihilation vertex reconstruction is emphasized.

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The ATHENA antihydrogen apparatus

Cited by 78 publications

References 57 publications

Production of slow protonium in vacuum

Production of slow protonium in vacuum

Real-time Detection of Antihydrogen Annihilations and Applications to Spectroscopy

Detection of Trapped Antihydrogen

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