| 41. |
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| 42. |
- Dion, Claude M., et al.
(författare)
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Time dependence of laser cooling in optical lattices
- 2005
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Ingår i: Europhysics letters. - Les Ulis : Éditions de physique. - 0295-5075 .- 1286-4854. ; 72:3, s. 369-375
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Tidskriftsartikel (refereegranskat)abstract
- We study the dynamics of the cooling of a gas of caesium atoms in an optical lattice, both experimentally and with 1D full-quantum Monte Carlo simulations. We find that, contrary to the standard interpretation of the Sisyphus model, the cooling process does not work by a continuous decrease of the average kinetic energy of the atoms in the lattice. Instead, we show that the momentum of the atoms follows a bimodal distribution, the atoms being gradually transferred from a hot to a cold mode. We suggest that the cooling mechanism should be depicted in terms of a rate model, describing the transfer between the two modes along with the processes occurring within each mode.
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| 43. |
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| 44. |
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| 45. |
- Forrey, Robert, et al.
(författare)
-
Collisions between metastable hydrogen atoms at thermal energies
- 2000
-
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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| 46. |
- 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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| 47. |
- Froelich, Piotr, et al.
(författare)
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Four-body treatment of the antihydrogen-positronium system : binding, structure, resonant states and collisions
- 2019
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Ingår i: Hyperfine Interactions. - : Springer. - 0304-3843 .- 1572-9540.
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Konferensbidrag (refereegranskat)abstract
- We have developed a coupled-rearrangement-channel method allowing the rigorous non-adiabatic treatment of the multi-channel scattering problem for four particles. We present the study of the binding, resonant and collisional properties of the (H) over bar -Ps system with the total angular momentum J = 0(+) (singlet positronic configuration). The binding energy, the life-times of the resonant states and the collisional cross sections are calculated and discussed. We present the preliminary cross sections for the elastic and inelastic (H) over bar -Ps scattering, notably for the excitation of Ps and for the rearrangement reaction producing the (H) over bar (+) ions.
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| 48. |
- Froelich, Piotr, et al.
(författare)
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Hydrogen : Antihydrogen Molecule and its Properties
- 2004
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Ingår i: Few-body systems. - : Springer Science and Business Media LLC. - 0177-7963 .- 1432-5411. ; 34:1-3, s. 63-72
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Tidskriftsartikel (refereegranskat)abstract
- The metastability of the four-body system is discussed from the point of view of radiative rearrangement collisions of the hydrogen and antihydrogen. Such collisions lead to the formation of an intermediate molecular state which further decays into positronium and protonium or is destroyed via annihilation. We present calculations of the lifetime of the system and the branching ratios for Coulombic decay and annihilation.
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| 49. |
- Froelich, Piotr, et al.
(författare)
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Hydrogen - Antihydrogen Collisions
- 2001
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Ingår i: Nuclear Physics A. - 0375-9474 .- 1873-1554. ; 692:1-2, s. 182c-183c
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Tidskriftsartikel (refereegranskat)
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| 50. |
- Froelich, Piotr, et al.
(författare)
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Hydrogen-antihydrogen collisions
- 2000
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 84:20, s. 4577-4580
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Tidskriftsartikel (refereegranskat)abstract
- Matter-antimatter interactions are investigated using hydrogen-antihydrogen collisions as an example. Cross sections for elastic scattering and for the antihydrogen loss (either through the rearrangement reaction, resulting in formation of protonium and positronium according to H+H →pp+1 e+e-, or via annihilation in flight) are calculated for the first time in a fully quantum mechanical approach. Implications for experiments intending to trap and cool antihydrogen are discussed.
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