Results of the Bielefeld-Brookhaven e+-H experiment

Weber, Marc H.; Hofmann, A.; Raith, Wilhelm; Sperber, Wolfgang; Jacobsen, F. M.; Lynn, Kelvin G.

doi:10.1007/bf02064508

Cited by 65 publications

(54 citation statements)

References 28 publications

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“…19,74,82 Also in Figure 6(a) we compare our results for the unscreened case with the corresponding results obtained by using different theoretical and experimental approaches. From these table and figure, we see that our present results are in close agreement with those theoretical and experimental results 83,84 for the unscreened case.…”

Section: Positronium Formationsupporting

confidence: 95%

Positron scattering from hydrogen atom embedded in weakly coupled plasma

2013

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The positron-hydrogen collision problem in weakly coupled plasma environment has been investigated by applying a formulation of the three-body collision problem in the form of coupled multi-channel two-body Lippmann-Schwinger equations. The interactions among the charged particles in the plasma have been represented by Debye-Huckel potentials. A simple variational hydrogenic wave function has been employed to calculate the partial-wave scattering amplitude. Plasma screening effects on various possible mode of fragmentation of the system e þ þ Hð1sÞ during the collision, such as 1s ! 1s and 2s ! 2s elastic collisions, 1s ! 2s excitation, positronium formation, elastic proton-positronium collisions, have been reported. Furthermore, a detailed study has been made on differential and total cross sections of the above processes in the energy range 13.6-350 eV of the incident positron. V C 2013 American Institute of Physics.

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Section: Positronium Formationsupporting

confidence: 95%

Positron scattering from hydrogen atom embedded in weakly coupled plasma

2013

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“…In Figure 2 we show the cross section measured by Zhou et al (1997) from threshold to greater than 100 eV, where it becomes negligible. Near the peak, this cross section is significantly less than that measured by Sperber et al (1992) (used by Wallyn et al 1994 andGuessoum et al 1997), but the Sperber measurement was later superseded by a new measurement by the same group (Weber et al 1994), which is consistent with the Zhou et al (1997) result.…”

Section: Positronium Formation Processessupporting

confidence: 79%

The Physics of Positron Annihilation in the Solar Atmosphere

Murphy

Skibo

et al. 2005

ASTROPHYS J SUPPL S

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We compile the most recently measured and calculated cross sections for processes relevant to annihilation of positrons in solar flares and present the final evaluated cross sections. We calculate the 511 keV annihilation line spectrum, the number of 2 line photons produced per positron, and the relative strength of the 3 continuum for each of the annihilation processes, using a Monte Carlo code that simulates the thermalization of and positronium production by $MeV positrons. We calculate the thermally averaged annihilation and positronium production rates and the positronium quenching rates. We apply the results to four specific environments (fully ionized, neutral, partially ionized, and a non-local thermodynamic equilibrium model of the quiet solar atmosphere), calculating the relative strengths of each process and the combined total annihilation line spectrum. The results are compared with data obtained recently from the high spectral resolution detectors of RHESSI. We find that positron annihilation in solar flares can occur in a wide variety of environments. The cross sections presented here are also useful for evaluation of positron annihilation in other environments such as the interstellar medium.

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“…For the simplest case of positron-hydrogen collision, the experimental measurement of Ps formation cross section is now amenable and reliable results have been obtained [3,4]. On the theoretical side, the Ps formation process has been widely investigated by several perturbation methods, such as the first-and second-order Born (FBA and SBA) [5,6], first and second distorted-wave approximations (DWA and SDWA) [7,8], polarized-orbital distorted-wave approximation (PODWA) [9,10], and the continuum distorted-wave (CDW) [11][12][13][14] methods.…”

Section: Introductionmentioning

confidence: 99%

Positronium formation for positron scattering from hydrogen: Maximum positions and scaling law

2011

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Ground-and excited-state positronium (Ps) formation from the hydrogen atom by positron impact at low and intermediate energies have been studied within the framework of two-center two-channel eikonal final state-continuum initial distorted wave model. A general method for obtaining Ps formation into arbitrary final states has been derived. The present results of Ps (1s), Ps (n = 2), and total Ps formation cross sections agree very well with previous close-coupling calculations and experimental measurements. The maximum positions of Ps(n) formation cross sections are found to be in good agreement with the prediction of wave vector matching model introduced by Charlton [J. Phys. B 39, 4575 (2006)]. We also present a scaling law for Ps (n) formation cross sections that is valid for all n in the entire energy range.

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Results of the Bielefeld-Brookhaven e+-H experiment

Cited by 65 publications

References 28 publications

Positron scattering from hydrogen atom embedded in weakly coupled plasma

Positron scattering from hydrogen atom embedded in weakly coupled plasma

The Physics of Positron Annihilation in the Solar Atmosphere

Positronium formation for positron scattering from hydrogen: Maximum positions and scaling law

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