| 1. |
- 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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| 2. |
- Piszczatowski, Konrad, et al.
(författare)
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Nonadiabatic treatment of hydrogen-antihydrogen collisions
- 2014
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Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics. - 1050-2947 .- 1094-1622. ; 89:6, s. 062703-
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Tidskriftsartikel (refereegranskat)abstract
- We present a nonadiabatic treatment of the hydrogen-antihydrogen system. The technique used to describe H-(H) over bar collisions is based on the coupled-rearrangement-channel method. Within this approach the total, nonadiabatic wave function of the system is divided into two parts: an inner and an outer one. To describe the inner part a set of square-integrable four-body functions is used. These functions are obtained by a diagonalization of the total Hamiltonian projected on a chosen L-2 subspace; they explicitly contain components of various arrangement channels expressed in terms of corresponding Jacobi coordinates. The outer part of the total wave function reflects its asymptotic character. Our procedure leads to a system of nonlocal integrodifferential equations that are solved iteratively and simultaneously determine the outer part of the solution and the coefficients in the four-body expansion of the inner part. To solve these equations the compact fine difference method was applied. Using this formalism we perform a one-channel calculation of the elastic scattering to obtain the S matrix, the nonadiabatic scattering length, and the cross section for the low-energy elastic scattering in the H-(H) over bar channel.
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| 3. |
- Voronin, Alexei, et al.
(författare)
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Gravitational quantum states of Antihydrogen
- 2011
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Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics. - 1050-2947 .- 1094-1622. ; 83, s. 032903-
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Tidskriftsartikel (refereegranskat)abstract
- We present a theoretical study of the motion of the antihydrogen atom ((H) over bar) in the gravitational field of Earth above a material surface. We predict that the (H) over bar atom, falling in the gravitational field of Earth above a material surface, would settle into long-lived quantum states. We point out a method of measuring the difference in the energy of (H) over bar in such states. The method allows for spectroscopy of gravitational levels based on atom-interferometric principles. We analyze the general feasibility of performing experiments of this kind. We point out that such experiments provide a method of measuring the gravitational force (Mg) acting on (H) over bar and that they might be of interest in the context of testing the weak equivalence principle for antimatter.
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| 4. |
- Voronin, Alexei, et al.
(författare)
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Hyperfine transitions in ultracold hydrogen : antihydrogen collisions
- 2009
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Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics. - 1050-2947 .- 1094-1622. ; 80:1, s. 010502-
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Tidskriftsartikel (refereegranskat)abstract
- We consider the hyperfine transitions in ultracold collisions of hydrogen (H) and antihydrogen ((H) over bar) atoms. The cross sections for transitions between various spin states are calculated. We show that hyperfine transitions in (H) over bar -H collisions are basically driven by the strong force between proton and antiproton.
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| 5. |
- Voronin, Alexei, et al.
(författare)
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Interaction of ultracold antihydrogen with a conducting wall
- 2005
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Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics. - 1050-2947 .- 1094-1622. ; 72:6, s. 062903/1-062903/11
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Tidskriftsartikel (refereegranskat)abstract
- We investigate the interaction of ultracold antihydrogen with a conducting surface, focusing on the phenomenon of quantum reflection. We calc. the reflection probability as a function of incident atom energy. We find that, for ground-state H atoms (with T<10-5 K), the probability of reflection is R.simeq.1-kb, where k is the momentum of the atom and b=2174.0 a.u. is a const. detd. solely by the van der Waals-Casimir tail of the atom-wall interaction. We show that quantum reflection, which suppresses the direct contact of ultracold atoms with the surface, allows for the possibility of confinement and storage of sufficiently cold antihydrogen atoms. We calc. the lifetime of H atoms enclosed in between solid walls. We develop a theory of H in a waveguide and propose some applications, notably the measurement of retardation corrections in the long-range component of the antiatom-wall potential. We demonstrate the existence of quantized states for antihydrogen atoms falling onto conducting surface in the gravitational field of Earth. We calc. the lifetime of ultracold H in its lowest gravitational state and obtain t=(Mgb/2h)-1.simeq.0.1 s, where Mg is a gravitational force acting on the antiatom. We propose that measurement of this lifetime may provide a new test for the gravitational properties of antimatter.
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| 6. |
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| 7. |
- Voronin, Alexei, et al.
(författare)
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Spin-exchange in hydrogen-antihydrogen collisions
- 2009
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Ingår i: Journal of Physics B. - : IOP Publishing. - 0953-4075 .- 1361-6455. ; 42:12, s. 125204-
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Tidskriftsartikel (refereegranskat)abstract
- We consider spin exchange in ultracold collisions of hydrogen (H) and antihydrogen ((H) over bar) atoms. The cross sections for transitions between various hyperfine states are calculated. We show that the process of spin exchange in (H) over bar -H collisions is basically driven by the strong force between a proton and an antiproton.
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