| 1. |
- Adrich, P., et al.
(författare)
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Production of antihydrogen atoms by 6 keV antiprotons through a positronium cloud
- 2023
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Ingår i: European Physical Journal C. - : Springer Nature. - 1434-6044 .- 1434-6052. ; 83:11
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Tidskriftsartikel (refereegranskat)abstract
- We report on the first production of an antihydrogen beam by charge exchange of 6.1 keV antiprotons with a cloud of positronium in the GBAR experiment at CERN. The 100 keV antiproton beam delivered by the AD/ELENA facility was further decelerated with a pulsed drift tube. A 9 MeV electron beam from a linear accelerator produced a low energy positron beam. The positrons were accumulated in a set of two Penning-Malmberg traps. The positronium target cloud resulted from the conversion of the positrons extracted from the traps. The antiproton beam was steered onto this positronium cloud to produce the antiatoms. We observe an excess over background indicating antihydrogen production with a significance of 3-4 standard deviations.
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| 2. |
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| 3. |
- Banerjee, D., et al.
(författare)
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Towards a test of the Weak Equivalence Principle of gravity using anti-hydrogen at CERN
- 2016
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Ingår i: 2016 Conference On Precision Electromagnetic Measurements (CPEM 2016). - 9781467391344
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Konferensbidrag (refereegranskat)abstract
- The aim of the GBAR (Gravitational Behavior of Antimatter at Rest) experiment is to measure the free fall acceleration of an antihydrogen atom, in the terrestrial gravitational field at CERN and therefore test the Weak Equivalence Principle with antimatter. The aim is to measure the local gravity with a 1% uncertainty which can be reduced to few parts of 10(-3).
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| 4. |
- Berggren, P., et al.
(författare)
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Impact of the strong force on the Coulombic decay of a hydrogen-antihydrogen molecule
- 2008
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Ingår i: Journal of Physics B. - : IOP Publishing. - 0953-4075 .- 1361-6455. ; 41:15, s. 155202-
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Tidskriftsartikel (refereegranskat)abstract
- The lifetime of the meta-stable hydrogen-antihydrogen molecule in various vibrational states is calculated. The partial lifetime with respect to the proton-antiproton annihilation is obtained from complex eigenvalues which arise upon inclusion of the strong force in the adiabatic formulation of the molecular decay problem. We study the influence of the strong force, which causes annihilation, on the transition probability for decay via Coulombic rearrangement to protonium and positronium.
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| 5. |
- Dalgarno, Alex, et al.
(författare)
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Collisions of H and Hbar
- 2001
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Ingår i: New Directions in Antimatter Chemistry and Physics. - : Kluwer Academic Publishers. - 0792371526 ; , s. 47-52
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Bokkapitel (refereegranskat)
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| 6. |
- Forrey, Robert C., et al.
(författare)
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Nonadiabatic coupling in cold collisions of spin-polarized metastable hydrogen atoms
- 2007
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Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics. - 1050-2947 .- 1094-1622. ; 76:5, s. 052709-
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Tidskriftsartikel (refereegranskat)abstract
- Previous calculations of low-temperature cross sections for collisions between spin-polarized metastable hydrogen atoms are improved to include nonadiabatic radial and angular coupling at large interatomic separations. The electrostatic dipole-quadrupole interaction produces nonadiabatic radial coupling between (2s,2p) and (2p,2p) states, while the Coriolis interaction produces nonadiabatic angular coupling. Both of these long-range contributions are handled in a space-fixed atomic gauge that is particularly convenient for a spin-polarized system. The improved theoretical results are compared with an existing experiment.
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| 7. |
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| 8. |
- Forrey, Robert, et al.
(författare)
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Collisions between metastable hydrogen atoms at thermal energies
- 2000
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 85:20, s. 4245-4248
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Tidskriftsartikel (refereegranskat)abstract
- The complex interaction potentials arising in the approach of two metastable hydrogen 2s atoms are calculated and the cross sections for ionization, excitation transfer, and elastic scattering are predicted. The measured cross section for associative ionization at E = 4.1 meV equals 2×10-15 cm2. We calculate a total ionization cross section of 2×10-13 cm2, varying as E-2/3 at higher energies. Thus it appears that dissociative ionization is the major ionization channel. We find also that double excitation transfer into two excited H(2p) atoms is still more probable with the large cross section of 9×10-12 cm2 at E = 4.1 meV varying as E-1/2 at higher energies. The detection of the resulting Lyman alpha photons would provide a diagnostic test of our predictions.
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| 9. |
- Froelich, Piotr, et al.
(författare)
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Antihydrogen in Interaction with Atoms and Surfaces
- 2005
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Ingår i: AIP Conference Proceedings. - : AIP. - 0094-243X .- 1551-7616. ; 770:1, s. 51-67, s. 51-67
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Tidskriftsartikel (populärvet., debatt m.m.)abstract
- Anoverview of the antiatom interactions with matter is given inthe context of the ongoing efforts to trap and coolantihydrogen at CERN. We show how the atom-antiatom scattering can,in addition to annihilation, result in a number of collisionalreactions such as elastic scattering, rearrangement to protonium and positronium,and even radiative association leading to formation of unusual short-livedatom-antiatom molecules. We also show that sufficiently cold antiatoms canbe reflected from material walls. The rates for these reactionsare of interest for the experiments with antihydrogen atoms atCERN, they probe the feasibility of collisional cooling of antihydrogenand they contribute to the understanding of stability of matterin contact with antimatter in general.
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| 10. |
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