| 1. |
- Adrich, P., et al.
(författare)
-
Production of antihydrogen atoms by 6 keV antiprotons through a positronium cloud
- 2023
-
Ingår i: European Physical Journal C. - : Springer Nature. - 1434-6044 .- 1434-6052. ; 83:11
-
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.
|
|
| 2. |
- Dalgarno, Alex, et al.
(författare)
-
Collisions of H and Hbar
- 2001
-
Ingår i: New Directions in Antimatter Chemistry and Physics. - : Kluwer Academic Publishers. - 0792371526 ; , s. 47-52
-
Bokkapitel (refereegranskat)
|
|
| 3. |
|
|
| 4. |
- 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
-
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.
|
|
| 5. |
- Froelich, Piotr, et al.
(författare)
-
Antihydrogen in Interaction with Atoms and Surfaces
- 2005
-
Ingår i: AIP Conference Proceedings. - : AIP. - 0094-243X .- 1551-7616. ; 770:1, s. 51-67, s. 51-67
-
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.
|
|
| 6. |
- Froelich, Piotr, et al.
(författare)
-
Formation of the Positronium Antihydride Molecules (HPs in Low Energy, 5-Body Collisions of Antihydrogen Ion H+with Positronium Atoms Ps
- 2024
-
Ingår i: Few-body systems. - : Springer. - 0177-7963 .- 1432-5411. ; 65:3
-
Tidskriftsartikel (refereegranskat)abstract
- In this paper we present the first pilot calculation of the elastic and inelastic cross sections for the 5-body scattering of antihydrogen ions with positronium atoms. These cross sections have not been calculated before and are not known experimentally. In particular, we focus on the collisional rearrangement reactions H(+)+Ps -> HPs+e(+) which deplete the H+ions and result in stable atomcules HPs. To better understand the mechanism of this rearrangement, we study the 3-dimensional, angle resolved positron densities of the 3- and 4-body fragments in the initial and final states of the rearrangement collision.
|
|
| 7. |
- Froelich, Piotr, et al.
(författare)
-
Four-body treatment of the antihydrogen-positronium system : binding, structure, resonant states and collisions
- 2019
-
Ingår i: Hyperfine Interactions. - : Springer. - 0304-3843 .- 1572-9540.
-
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.
|
|
| 8. |
- Froelich, Piotr, et al.
(författare)
-
Hydrogen : Antihydrogen Molecule and its Properties
- 2004
-
Ingår i: Few-body systems. - : Springer Science and Business Media LLC. - 0177-7963 .- 1432-5411. ; 34:1-3, s. 63-72
-
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.
|
|
| 9. |
- Froelich, Piotr, et al.
(författare)
-
Hydrogen - Antihydrogen Collisions
- 2001
-
Ingår i: Nuclear Physics A. - 0375-9474 .- 1873-1554. ; 692:1-2, s. 182c-183c
-
Tidskriftsartikel (refereegranskat)
|
|
| 10. |
- Froelich, Piotr, et al.
(författare)
-
Hydrogen-antihydrogen collisions
- 2000
-
Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 84:20, s. 4577-4580
-
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.
|
|
